2.2 OSI Data Link Layer Configuration

Operation Manual – Non-IP Architecture 

Comware V3 

Table of Contents 


Chapter 1 OSI Model ..................................................................................................................... 1-1 

1.1 OSI Model Overview.......................................................................................................... 1-1 

1.2 Functions of OSI Model Layers ......................................................................................... 1-1 

1.3 OSI Model Versus TCP/IP Protocol Suite ......................................................................... 1-3 

Chapter 2 OSI Data Link Layer Configuration ............................................................................ 2-1 

2.1 Introduction to OSI Data Link Layer................................................................................... 2-1 

2.2 OSI Data Link Layer Configuration.................................................................................... 2-1 

2.2.1 Configuring in ATM networks .................................................................................. 2-1 

2.2.2 Configuring in FR networks..................................................................................... 2-2 

2.2.3 Configuring in X.25 networks .................................................................................. 2-2 

2.2.4 Configuring in HDLC networks................................................................................ 2-3 

2.3 Network Example............................................................................................................... 2-3 

2.3.1 Configuring X.25 in an OSI Network ....................................................................... 2-3 

2.3.2 Configuring FR in an OSI network .......................................................................... 2-4 

Chapter 3 OSI Network Layer Configuration .............................................................................. 3-1 

3.1 Introduction to OSI Network Layer..................................................................................... 3-1 

3.1.1 OSI Model Overview ............................................................................................... 3-1 

3.1.2 OSI addressing........................................................................................................ 3-2 

3.2 Network Protocols Used in OSI Model .............................................................................. 3-4 

3.2.1 Introduction to CLNP............................................................................................... 3-4 

3.2.2 Implementation of CLNP ......................................................................................... 3-4 

3.3 Routing Protocols Used in OSI Model ............................................................................... 3-6 

3.3.1 Basic Routing Elements in OSI Networks............................................................... 3-7 

3.3.2 IS-IS ........................................................................................................................ 3-9 

3.3.3 ES-IS ..................................................................................................................... 3-11 

3.3.4 Use of Static Route ............................................................................................... 3-13 

3.4 OSI Network Configuration .............................................................................................. 3-13 

3.4.1 Configuring CLNS ................................................................................................. 3-13 

3.4.2 Configuring ES-IS.................................................................................................. 3-15 

3.4.3 Configuring directly connected ESs ...................................................................... 3-17 

3.4.4 Configuring Static Prefix Route............................................................................. 3-18 

3.5 OSI Networking................................................................................................................ 3-18 

3.5.1 Routing domain Splitting ....................................................................................... 3-18 

3.5.2 CLNP/ES-IS/IS-IS over IP..................................................................................... 3-19 

3.6 Configuration Example .................................................................................................... 3-19 

3.6.1 OSI-only Network Configuration Example ............................................................ 3-19 

3.6.2 CLNP Over IP Configuration Example.................................................................. 3-25 

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Chapter 4 IPX Configuration ........................................................................................................ 4-1 

4.1 IPX Protocol Overview....................................................................................................... 4-1 

4.1.1 IPX Address Structure............................................................................................. 4-1 

4.1.2 RIP .......................................................................................................................... 4-2 

4.1.3 SAP ......................................................................................................................... 4-2 

4.2 IPX Configuration............................................................................................................... 4-4 

4.2.1 IPX Configuration Overview .................................................................................... 4-4 

4.2.2 Activating IPX.......................................................................................................... 4-4 

4.2.3 Enabling IPX Interface ............................................................................................ 4-5 

4.2.4 Configuring IPX Static Routes................................................................................. 4-5 

4.2.5 Configuring IPX Route Number Limitation .............................................................. 4-6 

4.2.6 Configuring the Related Parameters for IPX RIP.................................................... 4-7 

4.2.7 Configuring the Related Parameters for IPX SAP .................................................. 4-9 

4.2.8 Configuring IPX Trigger Update Feature .............................................................. 4-12 

4.2.9 Configuring IPX Split Horizon Feature .................................................................. 4-13 

4.2.10 Configuring Encapsulation Format of IPX Frame ............................................... 4-13 

4.2.11 Forwarding IPX Broadcast Packet with Type 20................................................. 4-14 

4.3 Displaying and Debugging IPX........................................................................................ 4-14 

4.4 Typical Example of IPX Configuration ............................................................................. 4-16 

4.4.1 Providing File Services and Directory Services through IPX Network.................. 4-16 

4.5 Troubleshooting IPX ........................................................................................................ 4-18 

4.5.1 Troubleshooting IPX Core Layer........................................................................... 4-18 

4.5.2 Troubleshooting IPX RIP....................................................................................... 4-19 

4.5.3 Troubleshooting IPX SAP ..................................................................................... 4-20 

4.5.4 IPX Routing Management Troubleshooting .......................................................... 4-22 

Chapter 5 DLSw Configuration .................................................................................................... 5-1 

5.1 DLSw Overview ................................................................................................................. 5-1 

5.1.1 Introduction.............................................................................................................. 5-1 

5.1.2 Differences between DLSw1.0 and DLSw2.0 ......................................................... 5-2 

5.1.3 Associated Protocols............................................................................................... 5-3 

5.2 DLSw Configuration........................................................................................................... 5-3 

5.2.1 Enabling Bridging and Bridge-Set........................................................................... 5-5 

5.2.2 Creating the Local DLSw Peer................................................................................ 5-5 

5.2.3 Creating the Remote DLSw Peer............................................................................ 5-6 

5.2.4 Configuring the Bridge-set Group Connected with DLSw....................................... 5-6 

5.2.5 Configure Timer Parameters of DLSw .................................................................... 5-7 

5.2.6 Configuring to Enable/Suspend the DLSw Performance........................................ 5-7 

5.2.7 Configuring the Ethernet Interface to Join into a Bridge-Set .................................. 5-8 

5.2.8 Configuring the Ahead Response Window of LLC2................................................ 5-8 

5.2.9 Configuring LLC2 Local Response Window ........................................................... 5-8 

5.2.10 Configuring the Queue Length Sending the LLC2 Packet.................................... 5-9 

5.2.11 Configuring the Modulus of LLC2.......................................................................... 5-9 

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5.2.12 Configuring Number of Transmission Retries of LLC2 ......................................... 5-9 

5.2.13 Configuring Local Response Delay Time of LLC2.............................................. 5-10 

5.2.14 Configuring Local Response Time of LLC2 ........................................................ 5-10 

5.2.15 Configuring BUSY Time of LLC2 ........................................................................ 5-11 

5.2.16 Configuring the P/F Waiting Time of LLC2 ......................................................... 5-11 

5.2.17 Configuring the REJ Status Time of LLC2 .......................................................... 5-11 

5.2.18 Configuring DLSw Version and Filtering for a Remote DLSw Peer.................... 5-12 

5.2.19 Enabling the Multicast function of DLSw2.0........................................................ 5-12 

5.2.20 Configuring Explorer Frame Retransmission ...................................................... 5-13 

5.2.21 Configuring to filter packets from Peers.............................................................. 5-13 

5.2.22 Configuring SDLC to be the Link Layer Protocol Encapsulated in an Interface ............. 5-13 

5.2.23 Adding the SDLC Encapsulated Synchronous Serial Port to a Bridge-Set.............. 5-14 

5.2.24 Configuring the Baud Rate of the Synchronous Serial Port................................ 5-14 

5.2.25 Configuring the Coding Scheme of the Synchronous Serial Port ....................... 5-15 

5.2.26 Configuring the Idle Coding Scheme of the Synchronous Serial Port ................ 5-15 

5.2.27 Configuring the SDLC Role................................................................................. 5-15 

5.2.28 Configuring the SDLC Virtual MAC Address....................................................... 5-16 

5.2.29 Configuring the SDLC Address........................................................................... 5-16 

5.2.30 Configuring the SDLC Peer................................................................................. 5-17 

5.2.31 Configuring the XID of SDLC .............................................................................. 5-18 

5.2.32 Configure the Length of the Queue for Sending SDLC Packets......................... 5-18 

5.2.33 Configuring the Local Response Window of SDLC ............................................ 5-18 

5.2.34 Configuring the Modulus of SDLC....................................................................... 5-19 

5.2.35 Configuring the Maximum Frame Length of SDLC............................................. 5-19 

5.2.36 Configuring the Number of Transmission Retries of SDLC ................................ 5-20 

5.2.37 Configuring the SAP Address on Transforming from SDLC to LLC2 ................. 5-20 

5.2.38 Configuring the Two-Way Data Transmission Mode of SDLC............................ 5-20 

5.2.39 Configuring the Poll Pause Timer of SDLC......................................................... 5-21 

5.2.40 Configuring the Primary Response Waiting Time of SDLC ................................ 5-21 

5.2.41 Configuring the Secondary Response Waiting Time of SDLC ........................... 5-22 

5.2.42 Configuring the local or remote reachability information..................................... 5-22 

5.3 Displaying and Debugging DLSw .................................................................................... 5-22 

5.4 DLSw Typical Configuration Examples ........................................................................... 5-24 

5.4.1 DLSw Configuration of LAN-LAN.......................................................................... 5-24 

5.4.2 DLSw Configuration of SDLC-SDLC..................................................................... 5-25 

5.4.3 Configuring DLSw for SDLC-LAN Remote Media Transformation ....................... 5-26 

5.4.4 Configuring VLAN-supported DLSw...................................................................... 5-28 

5.4.5 DLSw2.0 Configuration Example .......................................................................... 5-29 

5.5 Troubleshooting DLSw .................................................................................................... 5-31 

5.6 Tips for DLSw 2.0 Configuration...................................................................................... 5-32 

Chapter 6 DLSw Redundancy Configuration ............................................................................. 6-1 

6.1 DLSw Redundancy Overview ............................................................................................ 6-1 

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6.2 Configuring DLSw Redundancy......................................................................................... 6-3 

6.2.1 Enabling DLSw Redundancy .................................................................................. 6-3 

6.2.2 Enabling the Ethernet Switch Support Feature....................................................... 6-3 

6.2.3 Configuring the DLSw Redundancy Timer.............................................................. 6-4 

6.2.4 Displaying and Debugging DLSw Redundancy ...................................................... 6-4 

6.2.5 Configuration Example of DLSw Redundancy Without Switch Support ................. 6-5 

6.2.6 Configuration Example of DLSw Redundancy With Switch Support ...................... 6-7 

6.2.7 Troubleshooting DLSw Redundancy....................................................................... 6-8 

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Chapter 1 OSI Model 


1.1 OSI Model Overview 

Open System Interconnection (OSI) reference model was recommended and 

developed by International Standardization Organization (ISO). The purpose of the 

reference model is to interconnect open systems and enable them to communicate with 

each other. The OSI reference model is also known as OSI model. 

The OSI model comprises seven layers, as shown in Figure 1-1. 

Application 

PING 

Presentation 

Session 

Transport 

Network 

Data link 

Physical 

TP0, TP1, TP2, TP3, TP4 

CLNP/CLNS, ESIS, ISIS 

Ethernet, PPP, Frame Relay, HDLC, X.25 

Physical media 

Figure 1-1 Layers of OSI model and some of the protocols/applications running on 

them 

1.2 Functions of OSI Model Layers 

I. Physical layer 

The physical layer defines mechanical, electrical and functional specifications of 

interfaces (such as the mechanical characteristics of mechanical parts and connectors, 

the voltage levels used to represent binary digits) for connecting, maintaining, and 

disconnecting physical links. The commonly used physical connection specifications 

for data communication include EIARS-232 and RS-449. As a successor of RS-232, 

RS-449 allows longer transmission distance of cables. Ethernet networks, token ring 

networks, and fiber distribution data interface (FDDI) networks are all well known local 

area networks (LAN). 

II. Data link layer 

The data link layer defines specifications on sending/receiving data through the 

physical connection between two systems. Operations such as coding, framing, and 

error checking and controlling are performed on this layer. Error checking and 

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controlling is unnecessary on higher layers if the data link layer provides this service. 

However, to provide higher transmission rates, networks communicating through 

reliable transmission media perform error checking and controlling on a higher layer 

instead of on the data link layer. Network devices such as bridges operate at the data 

link layer. Following are some common protocols working at the data link layer. 

• High-level data link control (HDLC) procedure and corresponding synchronization 

and bit-oriented protocols 

• Protocols used to form LANs and specify access methods, such as Ethernet and 

token ring 

• Protocols used to form fast packet-based wide area networks (WANs), such as 

frame relay (FR) and asynchronous transfer mode (ATM) 

• Network driver interface specifications (NDIS) developed by Microsoft 

• Open data link interface (ODI) developed by Novell 

III. Network layer 

The network layer defines specifications on discovering and maintaining routes 

between systems and is engaged in data transmitting and switching. The network layer 

provides a unified interface to its upper layers; details about the lower layers are 

invisible to the upper layers. Routers operate on this layer. A router checks the network 

layer addresses of the received packets, determine the routes for the packets, and 

send the packets through its corresponding interfaces. Packets destined for a 

workstation in the local network are directly delivered to the network; whereas those 

destined for other networks are routed by routers between networks until they reach the 

destination network. Following are some protocols operating on the network layer. 

• Internet protocol (IP) 

• X.25 protocol 

• Internet packet exchange (IPX) protocol developed by Novell 

• VINES internet protocol (VIP) developed by Banyan 

IV. Transport layer 

The transport layer provides high-level control for transmitting data between systems. 

This layer provides more complicated features such as error handling, differentiated 

preferences, and security. Connection-oriented services between two end systems are 

available on this layer, through which you can transmit data with high quality and high 

reliability. The packet sequence control, flow control, and fragment identification are 

achieved on this layer. 

On transport layer, each fragment is assigned an identifier, which is checked when the 

fragment reaches the destination. If a destination end finds the data carried by the 

packet is corrupted, the corresponding module operating on the destination end 

requests the source end through transport layer to retransmit the packet. This kind of 

retransmission mechanism ensures that all data is delivered in proper sequence. 

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Besides, you can establish logical circuits on this layer to provide secure transmission 

services. 

Following are some non-OSI transport layer protocols capable of connection-oriented 

services. 

• Transmission control protocol (TCP) 

• Serial packet exchange (SPX) protocol developed by Novell 

• VINES inter-process communication (VIPC) protocol developed by Banyan 

• NetBIOS/NetBEUI developed by Microsoft 

V. Session layer 

Session layer coordinates information exchanges between systems by using session 

technologies or dialogs. Dialogs are not always necessary for data transmission, but 

they can identify the positions to retransmit data for some applications when 

connections fail temporarily. A dialog that is of fixed interval can be used to identify 

whether or not a specific group of data is successfully transmitted and whether or not 

you can transmit new data. 

VI. Presentation layer 

Protocols operating on presentation layer are components of operating system or 

applications running on workstations. On this layer, information is formatted for 

displaying or printing, codes (such as tags or specific graphic sequences) in data are 

interpreted, and data encryption and interpretation of characters of other character sets 

are also performed. 

VII. Application layer 

Application layer defines specifications for the applications that implement file 

transmission, session termination, information exchange (for example, E-mail transfer), 

and so on. Applications operating on this layer access the lower-layer services through 

the procedures defined on this layer. Following are some OSI application layer 

protocols. 

• Virtual termination 

• File transmission, access, and management (FTAM) 

• Distributed transaction processing (DTP) 

• X.400 

• X.500 

1.3 OSI Model Versus TCP/IP Protocol Suite 

The TCP/IP protocol suite is also hierarchical and comprises four layers: application, 

transport, network and network interface. 

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Application lay er 

Presentation lay er 

Application 

layer 

SMTP ,HTTP 

FTP ,Telent 

Session layer 

Transport lay er 

Transport 

layer 

TCP 

UDP 

Network layer 

Netw ork layer 

IP 

Data link layer 

ARP 

Netw ork 

adapter 

RARP 

Phy sical lay er 

Netw ork cable 

Figure 1-2 OSI model versus TCP/IP protocol suite 

The TCP/IP layers correspond to OSI layers as follows: 

• Application layer: Roughly corresponds to the application layer and presentation 

layer of the OSI model. Applications utilize network services through this layer. 

• Transport layer: Roughly corresponds to the session layer and transport layer of 

the OSI model. TCP and UDP (user datagram protocol) operate on this layer. They 

provide services such as flow control, error checking and packet sequencing. 

• Network layer: Corresponds to the network layer of the OSI model. Protocols 

responsible for packets routing and host addresses resolving, such as IP, ICMP 

(internet control message protocol), IGMP (internet group management protocol), 

and ARP (address resolution protocol), operate on this layer. 

• Network interface layer: Roughly corresponds to the data link layer and physical 

layer of the OSI model. Operations such as data formatting and sending data to 

cables are performed on this layer. 

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Chapter 2 OSI Data Link Layer Configuration 


2.1 Introduction to OSI Data Link Layer 

Data link layer protocols OSI model supports include Ethernet, Point-to-Point Protocol 

(PPP), High-level Data Link Control (HDLC), Frame Relay (FR), X.25, and 

Asynchronous Transfer Mode (ATM), among which Ethernet defines specifications for 

broadcast networks, PPP and HDLC define specifications for point-to-point networks, 

and FR and X.25 define specifications for networks that are of non-broadcast multiple 

access (NBMA) type. Refer to the Data Link Layer Protocols module for information 

about data link layer protocols. 

For OSI protocol stacks, CLNP, ES-IS, and IS-IS encapsulations are based on data link 

layer. Upon passed to data link layer from network layer, OSI packets are identified as 

CLNP packets, ES-IS packets, and IS-IS packets accordingly by the Initial Protocol 

Identifier (IPI) fields and are processed by CLNP, IS-IS, and ES-IS module respectively. 

Packets of different type have different IPI values, as described as follows: 

• The IPI value of a CLNP packet: 0x81 

• The IPI value of an ES-IS packet: 0x82 

• The IPI value of an IS-IS packet: 0x83 

2.2 OSI Data Link Layer Configuration 

Following sections describe configurations that are new to OSI networks. Refer to the 

Data Link Layer Protocols module for information about data link layer configuration of 

Ethernet, PPP, HDLC, FR, X.25, and ATM. 

2.2.1 Configuring in ATM networks 

Table 2-1 Configure in OSI ATM networks 

Operation Command Remark 

Enter system view system-view — 

Enter ATM PVC view 

pvc { pvc-name [ vpi/vci ] | 

vpi/vci } 

Refer to the ATM 

Configuration Commands 

section in Data Link Layer 

Protocols in Comware V3 

Command Manual 

Establish a CLNSOA 

map for the PVC 

map clns — 

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Display map 

information of the 

upper layer of ATM 

display atm map-info 

[ interface { interface-name | 

interface-type interface-num } 

[ pvc { pvc-name | vpi/vci } ] ] 

Optional and can be 

performed in any view 

2.2.2 Configuring in FR networks 

Perform basic FR data link layer configurations first before the following configuration. 

Refer to the FR Data Link Layer Configuration module for related information. 

Table 2-2 Configure in OSI FR networks 



Enter a serial 

interface view 

Establish a FR map 

for OSI packets 

Display FR map 

information 

interface type number 

[ .sub-number ] 

fr map clns dlci 

[ nonstandard | ietf ] 

[ compression frf9 ] 

display fr map-info 

[ interface interface-type 

interface-num ] 

— 

Required. The dlci 

argument ranges from 16 to 

1007 



2.2.3 Configuring in X.25 networks 

Perform basic X.25 data link layer configurations first before the following configuration. 

Refer to the Data Link Layer Protocols module and X.25 Configuration Commands 

module for related information. 

Table 2-3 Configure in OSI X.25 networks 



Enter a serial interface 

view 

Configure the default 

upper layer protocol 

carried by X.25 

protocol for the 

interface 

interface type number 

[ .sub-number ] 

x25 default-protocol 

[ protocol-type ] 

— 

Required. The protocol 

can be IP or CLNS 

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Configure an X.121 

address for mapping 

CLNS addresses 

Configure a PVC for 

IP/CLNS-encapsulated 

packets 

Display X.25 map 

information 

Display information 

about an X.25 virtual 

circuit 

x25 map clns 

x121-address 

x.121-address [ option ] 

x25 pvc pvc-number { ip 

protocol-address 

[ compressedtcp ] | 

clns }*x121-address 

x.121-address [ option ] 

display x25 map 

display x25 vc [ lci ] 

Required 

Required. The PVC 

number ranges from 1 to 

4094. 



Optional. The lci 

argument ranges from 1 

to 4095 

2.2.4 Configuring in HDLC networks 

Perform basic HDLC data link layer configurations first before the following 

configuration. Refer to the HDLC Data Link Layer Protocols Configuration Commands 

module for related information. 

Table 2-4 Configure in OSI HDLC networks 


Enable debugging 

for HDLC OSI 

packets 

debugging hdlc clns { in | 

in-out | out } [ interface 

interface-type 

interface-number ] 

Optional. This operation is 

performed in user view 

2.3 Network Example 

2.3.1 Configuring X.25 in an OSI Network 

I. Network requirements 

As Figure 2-1 shows, two routers, Router A and Router B, are connected through their 

serial interfaces. X.25 is used as the data link layer protocol to transmit CLNP packets. 

Router A operates in DCE (data communications equipment) mode, Router B operates 

in DTE (data terminal equipment) mode. 

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II. Network diagram 

V.24/V.35 cable 

Serial0/0/0 

Serial1/0/0 

Router A 

Router B 

Figure 2-1 Two routers connect through serial interfaces with X.25 employed 

III. Configuration procedure 

1) Configure Router A 

# Enable X.25 switching. 

system-view 

[H3C] x25 switching 

# Enter Serial 0/0/0 interface view. 

[H3C] interface serial 0/0/0 

#Configure an IP address and an X.121 address for the interface, encapsulating the 

interface with X.25 and configuring it to be operate in DCE mode. 

[H3C-Serial0/0/0] link-protocol x25 dce 

[H3C-Serial0/0/0] ip address 10.1.1.1 255.255.255.0 

[H3C-Serial0/0/0] x25 x121-address 20050514 

# Configure X.25 VC (virtual circuit) range. 

[H3C-Serial0/0/0] x25 vc-range bi-channel 

# Configure an X.121 address for mapping CLNS addresses 

[H3C-Serial0/0/0] x25 map clns x121-address 20050513 

2) Configure Router B 

Configuring Router B is the same as that of Router A except that it is configured to 

operate in DTE mode. 

2.3.2 Configuring FR in an OSI network 


As Figure 2-2 shows, two routers, Router A and Router B, are connected through their 

serial interfaces. Router A operates in FR DCE mode, Router B operates in FR DTE 

mode. 

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Router A 

Serial4/0/0 

Frame Relay 

Network 

DLCI=100 

Serial4/0/0 

Router B 

Figure 2-2 Two routers connect through serial interfaces with FR employed 



# Assign an IP address to the serial interface. 

system-view 

[H3C]interface serial 4/0/0 

[H3C-Serial4/0/0]ip address 10.1.2.1 255.255.255.0 

# Configure FR to be the data link layer protocol. 

[H3C-Serial4/0/0]link-protocol fr 

[H3C-Serial4/0/0]fr interface-type dce 

# Configure a local virtual circuit. 

[H3C-Serial4/0/0]fr dlci 100 

# Establish a FR map for OSI packets. 

[H3C-Serial4/0/0] fr map clns 16 ietf compression frf9 


Configuring Router B is the same as that of Router A except that it is configured to 

operate in DTE mode. 

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Chapter 3 OSI Network Layer Configuration 


3.1 Introduction to OSI Network Layer 

3.1.1 OSI Model Overview 

Open Systems Interconnection (OSI) reference model is a network model developed 

according to the proposals issued by International Standardization Organization (ISO). 

The goal of the reference model is to connect open systems to enable them to 

communicate with each other. The OSI reference model is also known as OSI model. 

OSI model comprises seven layers shown in Figure 3-1. 

Application 

PING 

Presentation 

Session 

Transport 

Network 

Data link 

Physical 

TP0, TP1, TP2, TP3, TP4 

CLNP/CLNS, ESIS, ISIS 

Ethernet, PPP, Frame Relay, HDLC, X.25 

Physical media 

Figure 3-1 OSI model and some of corresponding protocols 

The network layer of OSI model can provide connectionless network services (CLNS) 

and connection-oriented network services (CONS) simultaneously by using 

connectionless network protocols (CLNP) and connection-oriented network protocols 

(CONP). The specifications on packet format and communication are defined in 

corresponding protocol standardization documents. ISO also defines protocols 

concerning the exchange of routing information for providing forwarding services on 

network layer, such as Intermediate System-Intermediate System (IS-IS) and End 

System-Intermediate System (ES-IS). As these protocols are based on data link layer, 

they are considered part of the network layer protocols coexist with CLNP, and protocol 

data units (PDU) of these kinds of protocols are transmitted after encapsulated on data 

link layer. 

Routers that operate as ISs adopt OSI protocol stacks. They can provide 

comprehensive connectionless forwarding services for OSI packets. By employing 

IS-IS and ES-IS protocols, they can discover and generate CLNS routes dynamically, 

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according to which they can then forward CLNS packets using CLNP. (CLNP plays the 

same role in OSI protocol stack as Internet Protocol [IP] does in TCP/IP protocol stack.) 

• OSI forwarding is achieved through the cooperation of CLNP and data link layer 

protocols. 

• OSI routing is achieved through the cooperation of IS-IS, ES-IS, and static routing 

protocols. 

3.1.2 OSI addressing 

I. Address structure 

Different from IP addresses, OSI addresses are categorized into Network Service 

Access Point (NSAP) addresses and NET (Network entity titles) addresses. A node in 

an OSI network can have one or multiple NET addresses and multiple NSAP 

addresses. The NSAP address and NET address of an OSI node differ only in the last 

bit, which is known as N-selector and plays the same role as the port number does in 

TCP/IP protocol suite. 

IDP 

DSP 

AFI IDI High Order DSP SyStem ID 

SEL 

(1 octet) 

Area Address 

Figure 3-2 Structure of NSAP addresses 

As Figure 3-2 shows, an NSAP address comprises initial domain part (IDP), which is 

specified by ISO and identifies the organizations responsible for the assignment of the 

rest part of the address and the address format, and domain specific part (DSP), which 

is assigned by the selector identified by IDP. IDP and DSP are variable in length and the 

total length of the two can be no more than 20 bytes. 

• Area address 

IDP comprises authority and format identifier (AFI) and initial domain identifier (IDI). AFI 

defines the format of IDI. IDP, along with high order DSP (HO-DSP), which is part of 

DSP, identifies a routing domain or an area of a routing domain. So the information in 

the form of (IDP, HO-DSP) is known as area address. 

Normally, you need configure only one area address for a router. The area addresses of 

nodes that reside in one area are the same. You can configure up to three area 

addresses for a router, through which you can perform operations such as area 

aggregation, area separation, and area transformation. 

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• System ID 

The System ID of an NSAP address uniquely identifies an end system or a router in an 

area. The length of a system ID is variable. The system ID of a router is 48 bits or 6 

bytes length. A Router_ID is always associated with the corresponding system ID. 

Suppose a router uses the IP address of its Loopback0 interface (168.10.1.1 for 

example) as its Router_ID, then the system ID it uses in an IS-IS area can be generated 

as the following: 

Rewrite each dotted part of the Router_ID as a three-bit number; prepending 0s for 

those with a bit number less than three, you get a number something like this: 

168.010.001.001. You can then obtain a system ID by removing the three dots in this 

number and dividing it into three parts, each of which comprises four bits. In this 

example, the system ID is 1680.1000.1001. 

You can also generate system ID in other ways. No matter which way you use, one 

thing you must bear in mind is a system ID must be unique in an area. 

• SEL 

Short for NSAP selector, also noted as N-SEL. Similar to protocol identifiers in IP 

networks, different transport protocols have different SELs. The SEL for an IP network 

is 00. 

• Network entity title 

Network entity title (NET) contains network layer information about an IS (information 

about transport layer is not included, SEL=0). You can regard it as a special type of 

NSAP address. 

Normally, a router only needs to be assigned one NET address. As a router can be 

assigned up to three area addresses, you can assign up to three NET addresses to a 

router, which is necessary for keeping the validity of routes when reallocating areas, 

such as aggregating areas or dividing one area into multiple areas. 

Following examples describe meanings of parts of an NET address. 

Among the NET 47.0001.aaaa.bbbb.cccc.00: 

• Area = 47.0001 

• System ID = aaaa.bbbb.cccc 

• SEL = 00 

Among the NET 01.1111.2222.4444.00: 

• Area = 01 

• System ID = 1111.2222.4444 

• SEL = 00 

II. Type of address 

At present, two types of addresses are available in OSI model: IS-IS NET and CLNS 

NET. 

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• Addresses that are of IS-IS NET type are protocol-level addresses, they are only 

valid for IS-IS protocol. 

• Addresses that are of CLNS NET type are real OSI network layer addresses. A 

CLNS NET is the unique valid address that represents the network layer access 

identifier. The source network addresses of all OSI packets (except IS-IS packets), 

such as error report packets, Ping packets, and ES-IS packets, are of CLNS NET 

type. A device determines whether a received packet is destined for it by 

comparing the destination address of the received CLNP packets with its CLNS 

NET. 

• At present, a device can be assigned to up to three IS-IS NET or CLNS NET 

addresses. Both of these two types of addresses have a minimum length of 8 

bytes and maximum length of 20 bytes. Addresses of different types are 

independent to each other. You can configure these two types of addresses 

separately. 

Note the following when configuring an IS-IS NET address: 

• When configuring multiple addresses for a device, make sure the System ID fields 

in these addresses are the same. For example, For an IS-IS NET address 

47.0001.aaaa.bbbb.cccc.00, its Area ID is 47.0001, System ID is aaaa.bbbb.cccc, 

and SEL is 00. If you assign it to a device and then want to assign another IS-IS 

NET address to the device, you must make sure the System ID field of the new 

address is aaaa.bbbb.cccc too, such as 47.0002.aaaa.bbbb.cccc.00, or you will 

be prompted with an error message. 

• There is no similar limitation when you configure a CLNS NET address. 

Normally, one CLNS NET and one IS-IS NET address are sufficient for a router. But for 

dividing and aggregating areas, you can also assign multiple IS-IS NET addresses to a 

router. 

3.2 Network Protocols Used in OSI Model 

3.2.1 Introduction to CLNP 

CLNP is a network layer protocol of the OSI model defined by ISO. As defined in ITU-T 

Rec.X.213|ISO/IEC 8348, CLNP is used to provide connectionless network services 

and implement some management functions on network layer. CLNP transmits data 

and error messages in a connectionless way using basic connectionless network 

services actual subnets/data links provide. 

3.2.2 Implementation of CLNP 

I. Packet processing 

CLNP is used to debugging and forwarding CLNP packets on network layer. Basically, 

CLNP packets are processed as follows: 

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• Step 1: Receive CLNP packets from data link layer and manipulate them in the 

following ways: discards packets that contain errors and return error report 

packets to the source if the E/R flag is set to 1; go to step 2 if the packets are 

normal. 

• Step 2: Look up in CLNS routing table for matched route entries according to the 

destination addresses to determine if the packets are to be passed to the upper 

layer modules or to be forwarded. 

• Step 3: For packets that are to be passed to the upper layer modules, strip off the 

CLNP headers and pass them to corresponding upper layer modules. For those 

that are to be forwarded, send them to data link layer according to the information 

about outbound interface and next hops the routing table entries contain. 

II. CLNS routing table 

CLNS routing table is the key for routers to forward CLNP packets. Each router 

maintains a CLNS routing table. Each route entry in a CLNS routing table indicates the 

outbound interfaces to specific NSAP addresses, through which a packet can reach the 

next router along the route or the destination ES. 

There are three types of CLNS routing table: L0, L1, and L2, which are described in 

Table 3-1. 

Table 3-1 Different types of CLNS routing table 

Routing 

table type 

L0 routing 

table (table 

of direct 

routes) 

L1 routing 

table (table 

of 

intra-area 

routes) 

L2 routing 

table (table 

of 

inter-area 

routes) 

Content 

1, Routes discovered by 

ES-IS 

2, Static direct routes 

configured by users 

Intra-area routes 

discovered by IS-IS 

1, Inter-area routes 

discovered by IS-IS 

2, Static NSAP prefixes 

configured by users 

Remark 

The destination addresses are full NET 

addresses. Route entries in this type of 

routing tables are used to forward 

packets to directly connected devices. 

The destination addresses are System 

IDs. Route entries in this type of routing 

tables are used to forward packets in 

areas. 

The destination addresses are prefixes of 

NSAP addresses. Route entries in this 

type of routing tables are used to look up 

routes or forward CLNP packets between 

areas or routing domains. 

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Table 3-2 Ways to match a CLNS route entry 

Routing table type 

Remark 

L0 routing table 



Exact match 

Longest match 

III. Looking up a route 

Direct routes are always most preferred when a router forwards CLNP packets. A router 

forwards a CLNP packet directly if the destination NSAP of the packet exactly matches 

a route entry in the L0 routing table. If such route entries do not exist, the router 

determines whether the packet is to be forwarded to the local area or other areas 

according to the destination address and then determine the routing table to be looked 

up in as follows: 

1) Retrieves the area ID from the destination NSAP the CLNP packet carries and 

compares it with those maintained by IS-IS to see if the destination is in the same 

Level1 areas the reachable area IDs identify. 

• If yes, the router retrieves the system ID from the CLNP packet and looks it up in 

the L1 routing table for exactly matched route entries. 

• If the destination is not in the same Level1 areas the reachable area IDs identify, 

the router looks up in L2 routing table for the longest matched route entry. 

2) No matched routes exist in any of the routing tables. 

• Try to find the default CLNS route. This is the last option for forwarding CLNP 

packets. 

Note: 

For multiple matched route entries in a routing table that are discovered by different 

protocols, a router makes its choice in the following ways: 

• Categorize these route entries according to the priorities of the routing protocols that 

discover these routes. 

• Choose the one with the highest priority. 

3.3 Routing Protocols Used in OSI Model 

Routing protocols used in OSI model include IS-IS and ES-IS, among which: 

• IS-IS is used to discover routes to ISs inside or outside an area. 

• ES-IS is used to discover routes to ESs or ISs directly connected to the device. 

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The two routing protocols, IS-IS and ES-IS, which cooperates with each other, form the 

routing system of an OSI network. 

3.3.1 Basic Routing Elements in OSI Networks 

As Figure 3-3 shows, an OSI network comprises components of various types, such as 

ES, IS, area, and domain. 

Area 0003 

Area 0001 

1 

E1/0/3 

IS1 

E1/0/1 

2 

IS0 

E1/0/1 

E1/0/2 

7 

E1/0/2 

ES0 

Domain47.0002 

6 

E1/0/3 

IS2 

E1/0/1 

E1/0/2 

5 

E1/0/2 

ES1 

IS3 

IS4 

3 

4 

E1/0/1 

E1/0/2 

E1/0/2 

E1/0/1 

E1/0/1 

Area 0001 

ES3 

Area 0002 

Domain47.0001 

Figure 3-3 Components of an OSI network 

I. IS 

An IS plays the same role as a router does in TCP/IP networks. It is the primary unit to 

generate and propagate routes in IS-IS protocol. 

• Each IS generates a link state packet (LSP) and stores it in a database maintained 

by the IS. An LSP can be fragmented, it contains information about ISs and ESs 

directly connected to the IS and the corresponding metrics. An IS sends its LSP to 

its neighbor ISs. These ISs in turn send it to other ISs. Such a process goes on 

and on, through which LSPs are propagated. When LSPs of all ISs in an OSI 

network are generated and propagated, each IS is aware of the topology of the 

network. When the topology changes, such a procedure is processed again. 

II. ES 

An ES plays the same role as a host does in TCP/IP networks. ESs reside in areas and 

do not perform IS-IS routing operations. Communications between ESs and ISs are 

carried out by ES-IS protocol. 

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When perform communications between ESs, packets destined for a specified ES are 

transmitted to the IS that resides in the same area that the ES resides in and is directly 

connected to the ES first. The IS then retrieves the route to the ES and forwards the 

packet accordingly. Following are different cases when transmitting a packet between 

ESs: 

• If the destination ES and the source ES are in the same area and in the same 

subnet, the IS obtains the position information about the destination ES by 

receiving ESH packets and send the packet to the destination ES. If the IS finds a 

better route, it notifies the source by sending redirecting (RD) packets. 

• If the destination ES and the source ES are in the same area but in different 

subnet, the local IS looks up in the L1 routing table for the route to the destination 

ES and then forwards the packet accordingly. 

• If the destination ES and the source ES are not in the same area, the local IS 

sends the packet to the nearest Level 2 IS, which in turn forwards the packet to 

other Level 2 ISs until the packet reaches the destination area, where the packet is 

forwarded to the destination ES along a optimal route. 

III. RD 

Short for routing domain. ISs in an RD use the same routing protocol to exchange 

routing information. 

IV. Area 

An RD can be divided into multiple areas. 

V. ESH 

Hello protocol data units (PDU) sent by ESs. An ESH packet contains information about 

NSAP address. Routers that have ES-IS employed can discover routes to their 

neighbors in time and maintain these routes through received ESH and ISH packets. 

(Similar to IP address in TCP/IP networks, NSAP address is network address.) 

VI. ISH 

Hello PDUs sent by ISs. An IS maintains routes to its neighbor ISs by receiving and 

processing ISH packets. 

VII. LSP 

Link state PDU. An LSP packet contains all link state information about the IS that 

generates it. Each IS generates an LSP packet and sends it to other ISs. It also 

receives and process LSPs sent by other ISs in the area. 

VIII. NPDU 

Short for network protocol data unit. As the name implies, a NPDU is a PDU generated 

by a network protocol of OSI model, its counterpart in TCP/IP networks is IP packets. 

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3.3.2 IS-IS 

For an OSI CLNS network, routers in it and have CLNP protocol employed exchange 

routing information dynamically using IS-IS protocol as follows: 

• Data is routed by hops, with IS-IS protocol figuring out the optimal route and 

routing. 

• IS-IS protocol is a kind of IGP protocol and is applicable to an area. It chooses 

routes by their link state. 

• An IS can be configured as an L1 IS, an L2 IS, or an L12 IS. An L1 IS 

communicates with other ISs in the same area. L2 ISs are used to form the 

backbone of an OSI network. To simplify the design of an OSI network backbone, 

an L1 IS is only needed to communicate with the nearest L2 IS. 

Refer to the Routing Protocol section in this manual for more information about IS-IS 

protocol. 

I. Remarks on IS-IS networking 

IS-IS protocol can be integrated in multiple types of networks, such as IP networks, OSI 

networks, or OSI/IP hybrid networks. To prevent IP networks and OSI networks from 

influencing each other and ensure the integrity and validity of IP and CLNS routes, RFC 

1195 defines IS-IS integrated networking as follows: 

• Backbone areas (L2 area), L1 areas can be of only one of the following types: 

IP-only area, OSI-only area, or DUAL area. An IP-only area can contain IP-only 

ISs and DUAL ISs. Only IP packets can be properly forwarded in it. An OSI-only 

area can contain OSI-only ISs or and DUAL ISs. Only OSI packets can be properly 

forwarded in it. A DUAL area contains only DUAL ISs. Both IP packets and OSI 

packets can be properly forwarded in it. 

• An IP-only backbone area and an OSI-only backbone area cannot coexist in one 

RD. That is, an RD can have only one backbone area. If you want a backbone 

area to be both IP-capable and OSI-capable, configure it as a DUAL area. 

• An OSI-only area and an IP-only area cannot intersect. That is, an OSI-only or an 

IP-only area cannot have part of it be IP-only area while the rest is OSI-only area. 

• RDs can be categorized into IP-only type, OSI-only type, and DUAL type too. The 

backbone area and L1 areas of an IP-only RD are all IP-only areas, where only IP 

packets can be properly forwarded. The backbone area and L1 areas of an 

OSI-only RD are all OSI-only areas, where only OSI packets can be properly 

forwarded. For a DUAL RD, the backbone area must be a DUAL area, whereas 

the L1 areas can be only one of these three types: IP-only areas, OSI-only areas, 

and Dual areas. In DUAL RDs, OSI-only areas, DUAL areas, and backbone areas 

can be interconnected through OSI networks; IP-only areas, DUAL areas, and 

backbone areas can be interconnected through IP networks. 

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II. Descriptions on types of ISs 

Figure 3-4 demostrates the above mentioned three IS types. They are described as 

follows. 

• IS2 is an OSI-only IS, because all its interfaces that have IS-IS employed run IS-IS 

for OSI only. 

• IS3 is an IP-only IS, because all its interfaces that have IS-IS employed run IS-IS 

for IP only. 

• IS4 is an DUAL IS, because all its interfaces that have IS-IS employed run both 

IS-IS for IP and IS-IS for OSI. 

Serial1/0/0 Ethernet1/0/0 Serial1/0/0 Ethernet1/0/0 

isis enable clns 


isis enable ip 


Ethernet1/0/1 


Isis enable clns 

IS1 

Ethernet1/0/1 


IS2 

Serial1/0/0 


Ethernet1/0/0 


Serial1/0/0 



Ethernet1/0/0 

isis enableclns 

isis enableip 

Ethernet1/0/1 


IS3 

Ethernet1/0/1 



IS4 

Figure 3-4 Types of ISs 

Note: 

IS1 shown in Figure 3-4 is improperly configured. Because of its three interfaces that 

have IS-IS employed, one runs IS-IS for IP, one runs IS-IS for OSI, and the last runs 

both IS-IS for IP and IS-IS for OSI. 

Following are suggestions for establishing a simple and logical network: 

• Use OSI-only ISs in OSI-only areas. 

• Use IP-only ISs in IP-only areas. 

• Use DUAL ISs in DUAL areas. 

Although an IP-/OSI-only area still operates properly even you add DUAL ISs in it, but 

doing this is no good for the clarity of area structure and is thus not recommended. 

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3.3.3 ES-IS 

I. Introduction to ES-IS protocol 

ES-IS is a network layer protocol of OSI model defined by ISO, it is a routing protocol 

the OSI protocol suite contains. It is used to discover routes between ESs and ISs, and 

exchange configuration and routing information between ESs and ISs. 

During the course of discovering routes between ESs and ISs, an ES sends ESH 

packets to all ISs in the network, and an IS sends ISH packets to all ESs that reside in 

the subnet connected to the IS. By receiving all these packets, an IS discovers and 

maintains routes to its neighbors. 

ES-IS protocol is used for: 

• An ES to discover ISs. The IS in turn forwards NPDUs sourced from the ES to 

subnets not directly connected to the ES. 

• An ES to discover other ESs in the same subnet. 

• An IS to discover ESs in the subnets directly connected to it. 

• An ES to determine the IS to forward its NPDU packets when multiple ISs are 

available. 

II. Employing ES-IS protocol on a router 

When operating as an IS, a router can have ES-IS protocol employed. The router can 

then discover routes to its neighbors in time and maintain these routes through 

received ESH and ISH packets. 

• When an IS receives an ESH packets and does not find the corresponding ES in 

its neighbor list, it adds the ES to its neighbor list. Each ESH packet contains a 

Holding Time field, whose value specifies the interval the corresponding entry is 

allowed to exist in the neighbor list of an IS. That is, after an IS receives an ESH 

packet and adds the corresponding ES to its neighbor list, if the IS does not 

receive an ESH packet from the ES again for specified time, the ES is considered 

to be unreachable and the corresponding entry is removed from the neighbor list. 

• An IS updates information about an ES its neighbor list contains when the IS 

receives another ESH packet sourced from the corresponding ES, including the 

time when the IS receives the ESH packet and Holding Time value. 

• An IS maintains routes to its neighboring ISs by processing received ISH packets. 

• An IS that has ES-IS protocol employed sends ISH packets regularly to all its 

neighbors to trigger them to update corresponding routes. The interval for sending 

ISH packets, which defaults to 60 seconds, and the Holding Time of an ISH packet, 

which defaults to 180 seconds, are all configurable. 

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Note: 

• The difference between the interval to send ESH or ISH packets and the 

corresponding holding time can be neither too long nor too short. 

• An over-long sending interval may exhaust the holding time and thus results in an IS 

being regarded as an unreachable IS before the next ISH packet arrives. 

• An over-long holding time may cause an IS being not able to inform of changes of 

routing state in time and thus result in slow convergence. 

• Normally, the hold time is three times of the sending interval. 

III. The role ES-IS protocol plays in OSI protocol suite 

ES-IS protocol generates and maintains routes to directly connected devices. This kind 

of routes, along with intra- or inter-domain IS routes generated and maintained by IS-IS 

protocol, form the entire routing system of an OSI network, through which upper layer 

protocols such as CLNP can forward OSI packets. 

IV. Cooperation with IS-IS protocol 

Note: 

To propagate information about the neighboring ESs, you must employ both ES-IS and 

IS-IS for OSI protocols on corresponding interfaces. 

IS-IS protocol only adds ES-neighboring information of the interfaces with IS-IS for OSI 

employed to LSPs for the information to propagate. For interfaces that do not have 

IS-IS protocol employed or have IS-IS for IP employed, their ES-neighboring 

information is not added to LSPs. 

In Figure 3-5, to propagate ES neighboring information of the Ethernet0/0/0 interface of 

IS2 through IS-IS LSP for IS1 to figure out the route to ES 1, you need to employ ES-IS 

protocol to the Ethernet0/0/0 interface of IS2 using the esis enable command to enable 

IS 2 to find ES1, you need also to employ IS-IS protocol to the interface using the isis 

enable clns command to enable ES neighboring information about ES1 to propagate 

through LSP. 

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IS 1 IS 2 

Ethernet0/0/0 

ES 1 

Figure 3-5 Combination of IS-IS and ES-IS 

3.3.4 Use of Static Route 

• You can configure static routes in OSI networks to enable packets being routed to 

directly connected ESs or being routed between areas. When configuring a static 

route, you need to specify the destination address and the outbound interface. You 

need also specify the Layer 2 address of the next hop if the static route is for a 

broadcast interface. The destination address of a static route that lead to an ES is 

an NSAP address, and the destination address of an inter-area static route is an 

NSAP prefix. 

• You need to add/remove static route entries manually. A static route is also 

affected by interface state. If the outbound interface changes from up to down, the 

corresponding route is removed from the routing table. And a removed static route 

comes back if the corresponding interface changes from down to up. 

• Static routes can be configured to be of the same cost or to be of reject or 

blackhole type. 

• Static routes can cooperate with dynamic routing protocols. Besides, an OSI can 

also be completely routed by static routes. 

3.4 OSI Network Configuration 

3.4.1 Configuring CLNS 

I. Prerequisites 

Before performing CLNS configuration, make sure the router supports CLNS. 

II. CLNS configuration 

Figure 3-3 lists CLNS configuration procedures. 

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Table 3-3 Configure CLNS 



Enable 

globally 

CLNS 

clns enable 

Required. CLNS is disabled 

by default 

Assign a NET 

address to the IS 

Enable generation of 

error report packets 

Set the minimum 

interval to generate 

two successive error 

report packets 

clns net address 

clns erpacket enable 

clns erpacket interval 

[ milliseconds ] 

Required. You can assign 

up to three NET addresses 

to a router 

Optional. Generation of 

error report packets is 

disabled by default 

Optional. The default 

minimum interval to 

generate two successive 

error report packets is 10 

milliseconds 

Reset 

information 

statistics 

reset clns statistics 

Optional 

Display 

information 

CLNS 

current 

about 

display clns 

Optional. You can display 

information about the 

current CLNS in any view 

Display all active 

CLNS routes 

display clns routing-table 

[ [ level-0 | level-1 | level-2 ] 

[ NSAP | verbose] ] | 

[ l2-cache ] 


all active CLNS routes in 

any view 

Display 

information 

CLNS flow 

statistics 

about 

display clns statistics 


statistics information about 

CLNS flow in any view 

Display information 

about CLNS 

interfaces 

Display CLNS routes 

generated by IS-IS 

display clns interface 

[ interface-type 


display isis routing 


information about CLNS 

interfaces in any view 


CLNS routes generated by 

IS-IS in any view 

Test the reachability 

of a specified CLNS 

peer 

ping clns NSAP — 

Detect the nodes a 

route that lead to a 

specified NSAP peer 

contains 


for RD packets 

tracert clns [ -m max-TTL | 

-n n-request | -t timeout | -v ] 

* NSAP 

debugging clns rd 

— 

Optional. You can enable 

debugging for RD packets 

in user view 

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for Layer 3 CLNS 

routing table 

debugging clns routing 

Optional. You can enable 

debugging for Layer 3 

CLNS routing table in user 

view 

Caution: 

• As CLNS NET information is propagated through IS-IS, and routers with IS-IS 

protocol employed only propagate CLNS NET inforamtion of the network devices 

with Area IDs identical to theirs, make sure the Area ID of the network device for 

which you are configuring CLNS NET is identical to that of the IS-IS NET configured 

for the router, otherwise, the CLNS NET information of the device cannot propagate 

through the router, which results in other ISs being unable to learn the CLNS NET 

information. 

• It is recommended that you configure the CLNS NET to be identical to the 

corresponding IS-IS NET. 

• The clns erpacket interval command can be used to prevent error packet attack on 

the router. But the executing of the tracert clns command depends on error report 

packet rate. Therefore, if you use the clns erpacket interval command to set an 

overlong interval, when you use the tracert clns command to diagnose the network, 

if the system cannot receive a timely response, it will consider it network failure; on 

the contrary, if you set a too short interval, the burden of CPU will be increased. 

Therefore, you should set an appropriate interval. 

3.4.2 Configuring ES-IS 


Before performing ES-IS configuration, make sure you perform related CLNS 

configuration on the router. 

II. ES-IS configuration 

Table 3-4 lists ES-IS configuration procedure. 

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Table 3-4 Configure ES-IS 



Employ ES-IS protocol and 

enter ES-IS configuration view 

esis Required 

Employ 

ES-IS 

protocol 

on an 

interface 

Enter an interface 

view 

Employ 

protocol 

ES-IS 

interface 


interface-number 

esis enable 

— 

Optional. ES-IS protocol is 

disabled on an interface by 

default 

Enable sending of RD packets 

clns 

enable 

rdpacket 

Optional. Sending of RD 

packets is enabled by 

default. An RD packet is 

sent when the outbound 

interface of the NPDU is 

the inbound interface 

Set the minimum interval to 

generate RD packets 

clns rdpacket 

interval 

{ milliseconds } 

Optional. The default is 

100 milliseconds 

Set the holding time of the 

information a RD packet 

carries 

clns 

rdpacket 

[ seconds ] 

timer 

holding 


180 second 

Set the interval to send ISH 

packets 

timer 

configuration 

[ seconds ] 

Optional. The default is 60 

seconds 

Set the holding time of the 

information an ISH packet 

carries 

timer 

[ seconds ] 

holding 


180 seconds 

Reset ES-IS flow statistics 

information 

reset 

statistics 

esis 

Optional 

Display related information 

about neighbors discovered by 

ES-IS protocol 

Display ES-IS-related 

information about a Specified 

interface 

display esis peer 

display esis 

interface 

[ interface-type 


Optional. You can perform 

this operation in any view 



Display statistics information 

about ES-IS flow 

display 

statistics 

esis 



Display current information 

about ES-IS protocol 

display esis 



Enable debugging for events of 

IS-IS ES neighbors 

debugging 

es-adjacency 

isis 


this operation in user view 

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Enable debugging for events of 

IS-IS ES neighbors 

debugging 

is-adjacency 

isis 



Enable debugging for ES-IS 

events 

debugging 

event 

esis 



Enable debugging for ES-IS 

packets 

debugging 

packet 

esis 



3.4.3 Configuring directly connected ESs 

I. Prerequistes 

Before configuring directly connected ESs, make sure you perform related CLNS 


II. Configuration for a directly connected ES 

Table 3-5 lists directly connected ES configuration procedure. 

Table 3-5 Configure a directly connected ES 


Configure a directly 

connected ES 

Enable sending of 

RD packets 

Set the minimum 

interval to generate 

RD packets 

Set the holding time 

of the information a 

RD packet carries 

clns es-peer NSAP 


interface-number [ SNPA ] 

clns rdpacket enable 

clns rdpacket interval 

{ milliseconds } 

clns timer rdpacket holding 

[ seconds ] 

Optional. You need to 

configure 

static 

neighboring ESs for an IS if 

the IS does not have ES-IS 

protocol employed 

Optional. Sending of RD 

packets is enabled by 

default, where an RD 

packet is sent when the 

outbound interface of the 

NPDU is the inbound 

interface 


milliseconds 


second 

Set the interval to 

send ISH packets 

timer 

[ seconds ] 

configuration 


seconds 

Set the holding time 

of the information an 

ISH packet carries 

timer holding [ seconds ] 


seconds 

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3.4.4 Configuring Static Prefix Route 


Before configuring a static prefix route, make sure you perform related CLNS 


II. Static prefix route configuration 

Table 3-6 lists inter-area static prefix route configuration procedure. 

Table 3-6 Configure an inter-area static prefix route 



Configure 

inter-area 

prefix route 

an 

static 

clns route-static [ default-nsap-prefix | 

NSAP prefix ] interface-type interface-number 

[ SNPA ] [ reject | blackhole ] 

— 

3.5 OSI Networking 

3.5.1 Routing domain Splitting 

A routing domain comprises OSI-only backbone area and multiple OSI-only L1 areas. 

An OSI network usually has only one routing domain. 

A routing domain is usually split for two purposes: 

• Improving network performance and simplifying network structure 

• Splitting services 

A routing domain can be split in the following two ways: 

• Do not employ IS-IS protocol between physically connected routing domains. 

• Configure different authenticating keys for routing domains with IS-IS protocol 

employed in between to prevent these routing domains from communicating 

through IS-IS protocol. 

For a network that comprises multiple routing domains, you can employ IS-IS protocol 

in each routing domain to discover and generate CLNS routes, and enable routing 

domains to communicate with each other by configuring static routes between them. 

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Note: 

If you want routing domains to communicate with each other using static routes, you 

must configure different addresses prefixes for these routing domains to have all ISs in 

each of these routing domains share one address prefix. 

3.5.2 CLNP/ES-IS/IS-IS over IP 

As for OSI capability, routers are capable of CLNP/ESIS/ISIS over IP. That is, you can 

have OSI packets, such as CNLP/ES-IS/IS-IS packets, transmitted over TCP/IP 

networks, through which multiple OSI networks can be interconnected through TCP/IP 

networks. At present, you can have OSI packets transmitted over TCP/IP networks by 

encapsulating them using GRE. (Refer to GRE Configuration for more information 

about GRE.) 

• As Figure 3-6 shows, you need to establish a tunnel between ISs for CLNS 

packets to travel across TCP/IP networks and reach other not directly connected 

OSI networks. 

• The tunnel shown in Figure 3-6 is actually a virtual point-to-point connection. It 

provides a virtual interface that supports point-to-point connection only and 

enables GRE-encapsulated packets to travel along it. It also encapsulates packets 

using GRE and decapsulates GRE packets at its two ends. 

CLNP 

协议 

TCP/IP 

IP 协议 

IS 1 Tunnel 

IS 2 

CLNP 

协议 

Figure 3-6 Connect OSI networks using a TCP/IP network 

You can have IS-IS/ES-IS packets travel across TCP/IP network in similar ways. 

3.6 Configuration Example 

3.6.1 OSI-only Network Configuration Example 


The address prefixes of the two routing domains shown in Figure 3-7 are 47.0001 and 

47.0002 respectively. 

• Enable sending of RD packets on IS0, IS2, and IS4. 

• The minimum interval to send RD packets is 80 milliseconds on IS0, IS2, and IS4. 

• Employ ES-IS between IS0 and ES0. 

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Comware V3 




• Employ IS-IS between IS1 and IS2. 

• Employ IS-IS between IS1 and IS3. 

• Set a static prefix route between IS0 and IS2. 


1: L2 ISIS: Serial:PPP interf ace 

2: L2 ISIS: Ethernet 

3: L1 ISIS: Serial:PPP interf ace 

4: ESIS: Ethernet 


6: L1 ISIS: Ethernet 

7: Static: Ethernet 

8: ESIS: Serial: FR subinterf ace 


10: ESIS/L1 ISIS: Ethernet 

11: ESIS: Serial: PPP interf ace 

1 

area 0003 

s0/0/0 

e0/0/0 

2 

area 0001 

IS1 

e0/0/0 

IS0 

s0/0/0 

7 

e0/0/0 

s0/0/0 

IS2 

e0/0/1 

s0 

e0/0/0 

IS4 

s0/0/1 

8 

s0/0/0 

ES0 

domain47.0002 

6 3 

e0/0/0 

s0/0/0 

IS3 

11 

ES4 

IS5 

s0/0/1 

e0/0/2 

9 

e0/0/1 

5 4 

10 

e0/0/0 

e0/0/0 

e0/0/0 

e0/0/0 

ES1 

ES2 

ES3 

IS6 

area 0001 area 0002 

domain47.0001 

ES-IS Protocol 

Intra-Area IS-IS Protocol 

Inter-Area IS-IS Protocol 

Clns Static Route 

IS-IS Area Boundary 

Routing Domain Boundary 

Intermediate System 

End Sy stem 

Figure 3-7 Diagram of a typical OSI-only network 


1) Configure IS0. 

# Enter system view. 

system-view 

# Enable CLNS and assign an NET address to IS0. 

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Comware V3 


[H3C] clns enable 

[H3C] clns net 47.0002.0001.0000.0000.0010.00 

# Employ IS-IS globally and set the network entity name of the IS-IS routing process. 

[H3C] isis 

[H3C-isis] network-entity 47.0002.0001.0000.0000.0010.00 

[H3C-isis] quit 

# Employ ES-IS globally 

[H3C] esis 

[H3C-esis] quit 

# Configure Serial0/0/0 interface and encapsulate it using FR. 


[H3C-serial0/0/0] link-protocol fr 

[H3C-serial0/0/0] interface serial0/0/0.1 

[H3C-serial0/0/0.1] fr dlci 30 

[H3C-serial0/0/0.1] isis enable clns 

[H3C-serial0/0/0.1] esis enable 

[H3C-serial0/0/0.1] quit 

# Configure the static route to domain 47.00001. 

[H3C] clns route-static 47.0001 int e0 0000.5e00.0010 

# Enable sending of RD packets and set the minimum interval to send RD packets to 80 

milliseconds. 

[H3C] clns rdpacket enable 

[H3C] clns rdpacket interval 80 



system-view 



[H3C] clns net 47.0001.0003.0000.0000.0011.00 

# Employ IS-IS globally, set the level of the IS and the network entity name of the IS. 

[H3C] isis 

[H3C-isis] is-level level-2 



# Configure Serial 0/0/0 interface: Encapsulate it using PPP and enable CLNS. 

[H3C] interface serial0/0/0 

[H3C-serial0/0/0] link-protocol ppp 

[H3C-serial0/0/0] isis enable clns 

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Comware V3 


[H3C-serial0/0/0] quit 

# Configure Ethernet0/0/0 interface: Enable CLNS. 

[H3C] interface ethernet0/0/0 

[H3C-ethernet0/0/0] isis enable clns 

[H3C-ethernet0/0/0] quit 



system-view 



[H3C] clns net 47.0001.0001.0000.0000.0012.00 

# Employ IS-IS globally and set the network entity name of the IS. 

[H3C] isis 



# Configure Serial 0/0/0 interface: Encapsulate it using PPP and enable CLNS. 





# Configure Ethernet0/0/1 interface: Enable CLNS and set the level of the IS. 

[H3C] interface ethernet 0/0/1 


[H3C-ethernet0/0/1] isis circuit-level level-1 

# Configure the inter-area static prefix route between IS2 and IS0 (the NSAP address of 

the corresponding interface of the next hop) 

[H3C] clns route-static 47.0002 interface vlan-interface 2 0000.5e00.0011 


milliseconds. 





system-view 



[H3C] clns net 47.0001.0001.0000.0000.0013.00 

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Comware V3 


# Employ IS-IS globally and set the network entity name of the IS. 

[H3C] isis 

[H3C] is-level level-1 

[H3C] net 47.0001.0001.0000.0000.0013.00 

[H3C] esis 




#Configure Ethernet0/0/2 interface: Enable CLNS for IS-IS and CLNS for ES-IS. 



[H3C-ethernet0/0/2] esis enable 




system-view 



[H3C] clns net 47.0001.0002.0000.0000.0014.00 

# Enable IS-IS globally and set the network entity name of the IS. 

[H3C] isis 

[H3C] net 47.0002.0001.0000.0000.0014.00 


[H3C] interace ethernet 0/0/0 



# Configure Serial0/0/0 interface: Encapsulate the interface using PPP and enable 

CLNS. 



[H3C-serial0/0/0] isis enable 

[H3C-serial0/0/0] isis circuit-level level-1 



milliseconds. 




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Comware V3 



system-view 



[H3C] clns net 47.0001.0002.0000.0000.0015.00 

# Enable IS-IS and ES-IS globally and set the network entity name of the IS. 

[H3C] isis 

[H3C] net 47.0002.0001.0000.0000.0015.00 

[H3C] esis 

# Configure Serial0/0/0 interface and enable CLNS. 




# Configure Ethernet0/0/1 interface: Enable CLNS and employ ES-IS protocol. 




# Configure Serial0/0/1 interface: Enable CLNS and employ ES-IS protocol. 



[H3C-serial0/0/1] esis enable 




system-view 



[H3C] clns net 47.0001.0002.0000.0000.0016.00 

# Employ IS-IS and ES-IS protocol globally, set the level of the IS and the network entity 

name of the IS. 

[H3C] isis 

[H3C] is-level level-1 

[H3C] net 47.0001.0001.0000.0000.0016.00 

[H3C] esis 

# Configure Ethernet0/0/0 interface: Enable CLNS and employ ES-IS protocol. 




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Comware V3 


8) Configure ES0. 

# Enter System view. 

system-view 

# Enable CLNS and assign an NET address to ES0. 


[H3C] clns net 47.0002.0001.0000.0000.0010.00 

[H3C] esis 

# Configure Serial0/0/0 interface: Configure a sub-interface on the interface and 

encapsulate it using FR. 


[H3C-serial0/0/0] link-protocol fr 

[H3C-serial0/0/0] fr interface-type dce 

[H3C-serial0/0/0] interface Serial0/0.1 p2p 

[H3C-serial0/0/0.1] fr dlci 30 

[H3C-serial0/0/0.1] esis enable 

[H3C-serial0/0/0.1] quit 

9) Configure ES1. 


system-view 

# Enable CLNS and assign an NET address to ES1. 


[H3C] clns net 47.0001.0001.0000.0000.0021.00 

[H3C] esis 

# Configure Ethernet0/0/0 interface: Employ ES-IS protocol. 




Note: 

Configurations of ES2, ES3, and ES4 are the same as that of ES1 and thus are not 

mentioned here. 

3.6.2 CLNP Over IP Configuration Example 


• Area 49.0001 and Area 49.0011 are interconnected through Router A. 

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Comware V3 


• Area 49.0002 is connected to Area 49.0001 and Area 49.0011 through Router A 

and Router B. 

• Communications between Area 49.0002 and Area 49.0001 or area 49.0011 are 

GRE-encapsulated and are carried out through an IP-based network. 


Router A 

serial 1/0/0 serial 1/0/0 

ethernet 0/0/0 

IP Network 

IP Network 


Router B 


Host 

Host 

Host 

Host 

Host 

Host 

Area49.0001 Area49.0011 Area49.0002 

Figure 3-8 Network diagram for the implementation of CLNP over IP 


1) Configure Router A. 

# Enable CLNS and perform related configuration. 

system-view 


[H3C] clns erpacket enable 

[H3C] clns net 49.0001.0100.0110.0065.00 

[H3C] clns net 49.0011.0100.0110.0065.00 

# Perform IS-IS related configuration. 

[H3C] isis RD1 

[H3C-isis] network-entity 49.0001.0100.0110.0065.00 


[H3C-isis] is-level Level-1-2 


# Configura Ethernet0/0/0 interface. 


[H3C-ethernet0/0/0] isis enable clns RD1 


# Configure Ethernet0/0/1 interface. 


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Comware V3 




# Configure the Serial1/0/0 interface of Router A. 


[H3C-serial1/0/0] ip address 10.1.100.65 255.255.255.0 


# Configure the GRE-encapsulated tunnel between Router A and Router B. 

[H3C] interface tunnel12 

[H3C-Tunnel12] tunnel-protocol gre 

[H3C-Tunnel12] isis enable clns 

[H3C-Tunnel12] isis small-hello 

[H3C-Tunnel12] source serial1/0/0 

[H3C-Tunnel12] destination 10.2.100.65 

[H3C-Tunnel12] keepalive 10 3 areaid 

2) Configure Router B. 

# Enable CLNS and perform related configuration. 


[H3C] clns erpacket enable 

[H3C] clns net 49.0002.0100.0210.0065.00 

# Performa IS-IS related configuration. 

[H3C] isis RD1 


[H3C-isis] is-level Level-1-2 


# Configure Ethernet0/0/0 interface. 




# Configure the Serial1/0/0 interface of Router B. 


[H3C-serial1/0/0] ip address 10.2.100.65 255.255.255.0 


# Configure the GRE-encapsulated tunnel between Router A and Router B. 

[H3C] interface Tunnel21 

[H3C-Tunnel21] tunnel-protocol gre 

[H3C-Tunnel12] isis enable clns 

[H3C-Tunnel12] isis small-hello 

[H3C-Tunnel21] source serial1/0/0 

[H3C-Tunnel21] destination 10.1.100.65 

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Comware V3 


[H3C-Tunnel21] keepalive 10 3 areaid 

3-28


Comware V3 

Chapter 4 IPX Configuration 


4.1 IPX Protocol Overview 

IPX (Internetwork Packet Exchange) is a network layer protocol of NetWare. Its position 

in NetWare protocol family of Novell is similar to IP’s position in TCP/IP. It defines such 

contents as address structure of Novell network. 

IPX protocol is a connectionless protocol. Though both data and destination IPX 

address are included in IPX packet, the protocol can not confirm whether a packet has 

been forwarded successfully. Such functions as confirmation of forwarding success 

and connection control are provided by the protocol at the layer above IPX. In IPX, any 

IPX packet is considered as an independent entity, not related to any other IPX packets 

logically or sequentially. 

IPX protocol functions to fill in addresses, routes and forward information packets. For 

packets generated at the upper-layer, IPX forwards them out directly. For user data 

packets, IPX will first find the correct path in the routing information table and then 

forward them out. 

Note: 

In the implementation of Comware at present, the support for IPX features is only 

provided in the centralized devices. 

4.1.1 IPX Address Structure 

IPX address structure differs from that of IP. An IPX address consists of network 

address and node address, in the format of network ID and node value. 

Here, network ID identifies a physical network where a site lies, with the length of 4 

bytes expressed by an 8-digit hexadecimal. It is not necessary to input all of the 8 digits, 

and the 0s in front can be omitted. The node value is used to identify a node in the 

network, with the same structure as MAC address and the length of 6 bytes. And it is 

input as 3 groups of double-byte digits separated by “-“ and the 0s in front can be 

omitted. 

For example, in the IPX address bc.0-0cb-47, the network ID is bc (more specifically, it 

is 000000bc) and the node value is 0-0cb-47 (more specifically, it is 0000-00cb-0047). 

Therefore, IPX address can also be expressed in the form of N.H-H-H, in which N is 

network ID and H-H-H is node value. 

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Comware V3 


4.1.2 RIP 

IPX makes use of RIP to maintain and advertise dynamic routing information. 

A router mainly functions to forward packets between networks. When a client sends a 

packet between networks, instead of knowing what path the packet should pass to 

reach the destination, it only knows to transmit the packet to the nearest router and 

forward it via the next router. So a router must provide the network routing information 

which can be directly sent to destination or needs to be forwarded, so that when a 

router receives a packet, it can find the next one to transmit it. The routing information 

here can be statically configured or dynamically collected. 

RIP is an abbreviation for Routing Information Protocol. A router creates and maintains 

an inter-network routing information database (usually called router information table) 

through RIP. When the router starts, RIP begins exchanging routing information with 

other RIPs and maintains routing information table according to the changes of 

network. 

The following diagram describes the relation between main components of RIP. 

Router 

Information Table 

Routing Information 

Timer 

Periodic 

Broadcast Process 

RIP Process 

Aging Process 

Timer 

Socket 

0x 453 

RIP Request/Response Packets 

IPX Process 

NICs and Drivers 

Figure 4-1 Network diagram for the relation between main components of RIP 

This chapter introduces the RIP used by IPX. For the RIP configuration under IP 

environment, refer to “Routing Protocol” section in this manual. 

4.1.3 SAP 

Service advertising protocol (SAP) is used to advertise service types that servers 

provide and their addresses. When servers start, they broadcast their services through 

SAP, and when servers are shut down, they indicate the termination of services through 

SAP. 

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Comware V3 


Through SAP, a router creates and maintains an inter-network service information 

database (usually called server information table. It tells what services the network 

provides, and what inter-network addresses these servers have. This is an important 

function, for a workstation cannot establish session with file servers if it does not know 

their addresses. 

A server that provides services will periodically broadcast its service types and address 

to the directly connected sites. Clients cannot use such information directly. It is 

collected by SAP agents in different routers on the network, and saved in their server 

information tables. Since server information is often dynamically updated by SAP, 

clients can always obtain the latest server addresses. 

The following diagram describes the relation between main components of SAP. 

Server 

Information 

table 

Server Information 

Timer 

Periodic 

Broadcast 

Process 

SAP 

Process 

Timer 

Aging 

Process 

Socket 

SAP Request/Response packets 

0x452 

IPX 

NICs and Drivers 

Figure 4-2 Network diagram for the relation between main components of SAP 

SAP defines three types of packets, including service query, service response, and 

periodic broadcast. The following subsections describe how it operates: 

I. NetWare client initialization 

When a NetWare client is initializing, it needs to locate a server for connection. To this 

end, the client broadcasts a Get Nearest Server (GNS) request and expects responses 

from at least one router or server. A SAP response contains information such as data 

packet type, service type, and server name and address. 

Note that because the GNS request is broadcast, the client can only get responses 

from the servers and routers on the local IPX network. To contact servers on another 

network, the IPX router can get the routes to other network servers by sending RIP 

requests. 

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Comware V3 


II. Periodic update of SAP 

A server advertises its services by sending SAP broadcasts, providing service name 

and type, and its IPX address. The IPX routers that hear the broadcasts add the 

services in their service information database and broadcast these databases 

periodically on the directly connected networks. The advertisements thus can flood the 

entire network. By default, these broadcasts are sent every 60 seconds. 

4.2 IPX Configuration 

4.2.1 IPX Configuration Overview 

In IPX configuration, the necessary configuration for using IPX features includes: 

• Activate IPX 

• Enable IPX interface 

IPX supports static routing configuration. And after IPX is used on an interface, 

dynamic routing protocol RIP will be automatically enabled. The configuration related to 

routes includes: 

• Configure IPX static routes 

• Configure IPX route number limitation 

• Configure the related parameters for IPX RIP 

The SAP of IPX is enabled as soon as IPX is enabled. Users can also configure other 

parameters of SAP or service information according to the actual requirements. This 

configuration includes: 

• Configure the related parameters for IPX SAP 

The related configuration for IPX forwarding includes: 

• Configure IPX trigger update feature 

• Configure IPX split horizon feature 

• Configure encapsulation format of IPX frame 

• Forward IPX broadcast packet with type 20 

4.2.2 Activating IPX 

Perform the following configuration in system view. 

Table 4-1 Activate IPX 

Operation 

Command 

Activate IPX ipx enable [ node node ] 

Deactivate IPX 

undo ipx enable 

By default, IPX function is disabled. 

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Comware V3 


The node argument specifies the node value of the router. If no node value is specified, 

the router uses the MAC address of its first Ethernet interface. 

The following describes the node value assignment conventions: 

• If no node value is assigned to the router when IPX is activated, the router uses 

the MAC address of its first Ethernet interface as the node value of its serial 

interface. 

• If a node value is assigned to the router when IPX is activated, the router uses this 

value as the node value of its serial interface. 

For an Ethernet interface, its node value is its MAC address regardless of whether the 

router is assigned a node value. 

Note: 

If no Ethernet interface is available with the router, the system assigns a random node 

value based on the system clock. 

4.2.3 Enabling IPX Interface 

After activating the IPX function of a router, each independent interface must be 

assigned with a network ID so that IPX can run on the interface. 

Perform the following configuration in interface view. 

Table 4-2 Enable IPX interface 

Operation 

Enable IPX interface 

Delete IPX interface 

Command 

ipx network network-number 

undo ipx network 

By default, IPX is disabled on all interfaces after being started. 

If an IPX interface is deleted, the IPX configuration and static routing information of the 

interface will be deleted. 

4.2.4 Configuring IPX Static Routes 


4-5


Comware V3 


Table 4-3 Configure IPX static routes 

Operation 

Configure 

static routes 

IPX 

Command 

ipx route-static network { network.node | interface-type 

interface-num } [ preference value ] [ tick ticks hop hops ] 

Delete IPX static 

routes 

undo ipx route-static { network [ network.node | 

interface-type interface-num ] | all } 

The IPX static route with destination network ID -2 (0xFFFFFFFE) is the default route. 

On configuring the two parameters ticks and hops, the both are configured or neither is 

configured, rather than only one is configured. A tick is 1/18 second. 

In the implementation at present, the outgoing interface can only be encapsulated with 

PPP. 

4.2.5 Configuring IPX Route Number Limitation 

In IPX, the maximum dynamic route number and equivalent route number to the same 

destination address permitted in the routing table can be configured. The two 

configurations have no direct connection mutually, so changing one of the 

configurations will not affect the other. 


I. Configuring the maximum dynamic route number to the same destination 

address 

Table 4-4 Configure the maximum dynamic route number to the same destination 

address 

Operation 

Configure the maximum dynamic route 

number to the same destination address 

Restore the default configuration 

Command 

ipx route max-reserve-path paths 

undo ipx route max-reserve-path 

By default, the maximum dynamic route number to the same destination address is 4. 

If the newly configured value is less than the previously set value, the excessive routes 

will not be deleted until they get aging themselves or being deleted manually. 

Note: 

This configuration is independent of ipx route load-balance-path command. 

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Comware V3 


II. Configuring the equivalent route number to the same destination address 

Table 4-5 Configure the equivalent route number to the same destination address 

Operation 

Configure the equivalent route number 

to the same destination address 


Command 

ipx route load-balance-path paths 

undo ipx route load-balance-path 

By default, the equivalent route number to the same destination address is 1. 

If the newly configured value is less than the current active route number, the system 

will change the excessive active routes to inactive status. If the current active route 

number is less than the configured equivalent route number and there exist equivalent 

routes to the active routes, the system will change the routes to active status until the 

active route number equals to the configured equivalent route number. 

4.2.6 Configuring the Related Parameters for IPX RIP 

After IPX is enabled on an interface, the system will automatically enable RIP. Users 

can also perform the following configuration for the related parameters of RIP. 

• Configure updating interval of IPX RIP 

• Configure aging period of IPX RIP 

• Configure IPX RIP updating packet size 

• Configure the delay of interface sending IPX packets 

• Configure IPX RIP to import static routes 

I. Configuring updating interval of IPX RIP 

Users can configure the interval for RIP to update IPX module. The router will send RIP 

updating broadcast packet at intervals. 


Table 4-6 Configure IPX RIP updating interval 

Operation 

Configure IPX RIP updating interval 


Command 

ipx rip timer update seconds 

undo ipx rip timer update 

By default, the updating interval of IPX RIP is 60 seconds. 

II. Configuring aging period of IPX RIP 

The aging period of IPX RIP is dependent on the updating interval. Users can configure 

several updating intervals to one aging period. 

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Comware V3 



Table 4-7 Configure IPX RIP aging period 

Operation 

Configure IPX RIP aging period 


Command 

ipx rip multiplier multiplier 

undo ipx rip multiplier 

By default, the aging period is 3 times of RIP updating interval. In other words, if a 

routing table item is not updated after 3 RIP updating intervals, it will be deleted from 

the routing table, so will the corresponding dynamic service information table item be 

deleted from the service information table. 

III. Configuring IPX RIP updating packet size 


Table 4-8 Configure IPX RIP updating packet size 

Operation 

Configure IPX RIP updating packet size 


Command 

ipx rip mtu bytes 

undo ipx rip mtu 

By default, the size of IPX RIP updating packet is 432 bytes, which allows at most 50 

8-byte routing items in an RIP updating packet. 

IV. Configuring the delay of interface sending IPX packets 

In IPX RIP, two parameters hops and ticks are used to scale the distance to the 

destination network and perform routing choice. 

Ticks indicates the delay of time, with one tick is 1/18 second. The delay indicates the 

speed at which an interface forwards IPX packets: long delay means slow forwarding, 

and short delay means fast forwarding. Users can adjust the value of delay for the 

interface to send IPX packets. 


Table 4-9 Configure the delay of interface sending IPX packets 

Operation 

Configure the delay of interface sending IPX packets 


Command 

ipx tick ticks 

undo ipx tick 

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Comware V3 


By default, the delay of Ethernet interface is 1 tick, that of the asynchronous serial port 

is 30 ticks and that for WAN port is 6 ticks. The value of ticks ranges from 0 to 30000. 

V. Configuring IPX RIP to import static routes 

By importing routes, different routing protocols can share the peer routing information 

mutually. 


Table 4-10 Configure IPX RIP to import static routes 

Operation 

Configure IPX RIP to import static routes 

Remove the static routes imported by IPX RIP 

Command 

ipx rip import-route static 

undo ipx rip import-route static 

By default, IPX RIP does not import static routes. 

4.2.7 Configuring the Related Parameters for IPX SAP 

IPX SAP configuration includes: 

• Activate/deactivate SAP 

• Configure updating interval of IPX SAP 

• Configure aging period of IPX SAP 

• Configure IPX SAP updating packets size 

• Configure GNS response of IPX SAP 

• Configure IPX static service information table item 

• Configure length of service information reserve queue 

I. Activating/deactivating SAP 

SAP is enabled as soon as IPX is enabled on an interface. This configuration can be 

used when manually controlling the enabling of SAP function is necessary. 


Table 4-11 Activate/deactivate SAP 

Operation 

Deactivate IPX SAP 

Activate IPX SAP 

ipx sap disable 

Command 

undo ipx sap disable 

II. Configuring updating interval of IPX SAP 

In a huge network, one IPX SAP broadcast occupies much of the bandwidth. For 

interfaces running protocols such as PPP X.25 and frame relay, the bandwidth is limited. 

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Comware V3 


Therefore, changing IPX SAP updating interval is an effective method to reduce 

bandwidth occupation. 


Table 4-12 Configure updating interval of IPX SAP 

Operation 

Configure updating interval of IPX SAP 


Command 

ipx sap timer update seconds 

undo ipx sap timer update 

By default, the updating interval of IPX SAP is 60 seconds. 

During configuration users should make sure that all servers and routers on the 

network have the same SAP updating interval. Otherwise, it may occur that a router 

thinks a server fails to work, while the server is still working. 

III. Configuring aging period of IPX SAP 


Table 4-13 Configure aging period of IPX SAP 

Operation 

Configure aging period of IPX SAP 


Command 

ipx sap multiplier multiplier 

undo ipx sap multiplier 

By default, if a service information table item is not updated after 3 updating intervals, it 

will be deleted from the service information table. 

IV. Configuring IPX SAP updating packets size 


Table 4-14 Configure IPX SAP updating packets size 

Operation 

Configure IPX SAP updating packets size 


ipx sap mtu bytes 

undo ipx sap mtu 

Command 

By default, the maximum length of IPX SAP updating packets is 480 bytes, which 

means that a SAP updating packet can consist of 7 64-byte service information at most. 

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Comware V3 


V. Configuring GNS response of IPX SAP 

GNS (Get Nearest Server) is an SAP message, broadcast by NetWare clients which 

have enabled SAP. NetWare server will respond with GNS message. 

If there is a NetWare server in the client network segment, the server will respond. If 

there is not, the router will respond. 

Users can configure processing methods of a router to SAP GNS request: 

• Configure a router to respond using the nearest server information. 

• Configure a router to inform all servers it knows to respond in Round-robin 

method. 

• Configure an interface of a router to respond to the SAP GNS request or not. 


Table 4-15 Configure response method of a router to SAP GNS request 

Operation 

Perform GNS response in Round-robin method 

Perform GNS response using the nearest server 

information 

Command 

ipx sap gns-load-balance 

undo ipx sap 

gns-load-balance 


Table 4-16 Configure response method of a router interface to SAP GNS request 

Operation 

Disable reply to GNS request on the current 

interface 

Enable reply to GNS request on the current 

interface 

Command 

ipx sap gns-disable-reply 

undo ipx sap gns-disable-reply 

By default, for GNS request of SAP, a router will inform all servers it knows to respond 

in Round-robin method to avoid overload of one server. 

VI. Configuring IPX static service information table item 

Generally, the client only uses the service advertised by NetWare server and saved by 

a router. In special situation, the client can be specified to use specific service. 

In order that the client can always use a specific service, static service information can 

be manually added to the service information table. If the route related to the static 

service information is invalid or deleted, the static service information will be prevented 

from broadcasting, until the router finds a new valid route related to the service 

information. 


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Table 4-17 Configure IPX static service information table item 

Operation 

Add one IPX static service 

information table item 

Delete one IPX static service 

information table item 

Command 

ipx service service-type name network.node 

socket hop hopcount preference preference 

undo ipx service { { service-type [ name 

[ network.node ] ] [ preference preference] } | all } 

Similar to routing information, IPX service information possesses the concept of 

preference. The less the value of preference, the higher the preference of service 

information. By default, the preference of static service information is 60, and that of 

dynamic service information is 500. 

VII. Configuring length of service information reserve queue 

The maximum number of dynamic service information items of a service type can be 

adjusted via a command. 


Table 4-18 Configure length of service information reserve queue 

Operation 

Configure length of service information 

reserve queue 


Command 

ipx sap max-reserve-servers length 

undo ipx sap max-reserve-servers 

By default, the length of service information reserve queue is 2048. 

Note that the above commands only set a limit on dynamic service information items 

number not the static service information items number. If the length of service 

information queue a user configures is less than the original one, the service 

information table items will not be deleted. And if the service information items number 

of the same service type reaches to the configured value, new service information will 

not be added. 

IPX can support up to 10240 service information items with 5120 service types and 

5120 static service information items at most. 

4.2.8 Configuring IPX Trigger Update Feature 

IPX RIP and SAP periodically broadcast updating packets. If a router is not needed to 

send broadcast packets periodically, users can enable trigger updating feature on an 

interface. In this way, only when route or service information changes, will the router 

send updating packets. 


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Table 4-19 Configure IPX Trigger Update Feature 

Operation 

Enable trigger update feature on an interface 

Disable trigger update feature on an interface 

Command 

ipx update-change-only 

undo ipx update-change-only 

By default, trigger update feature is disabled on an interface. 

4.2.9 Configuring IPX Split Horizon Feature 

Split horizon is a way to avoid routing loops, i.e., routing information received from an 

interface is not permitted to be sent from the interface. In some cases, split horizon 

must be prohibited to ensure correct routing information transmission. Users are 

suggested to prohibit split horizon only when necessary. In addition, split horizon 

prohibition does not take effect to point-to -point connection links. 


Table 4-20 Configure IPX split horizon feature 

Permit split horizon 

Operation 

Prohibit split horizon 

ipx split-horizon 

Command 

undo ipx split-horizon 

By default, split horizon is permitted on an interface. 

4.2.10 Configuring Encapsulation Format of IPX Frame 

On WAN interfaces, IPX frame only supports PPP encapsulation at present. On 

Ethernet interfaces, encapsulation format of IPX frame can be changed via a 

command. 

Perform the following configuration in Ethernet interface view. 

Table 4-21 Configure Encapsulation Format of IPX Frame 

Operation 

Configure encapsulation format of IPX frame to 

802.2 


802.3 


Ethernet_II 

Command 

ipx encapsulation dot2 

ipx encapsulation dot3 

ipx encapsulation ethernet-2 

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Operation 


Ethernet_SNAP 



Command 

ipx encapsulation snap 

undo ipx encapsulation 

By default, encapsulation format of IPX frame on an Ethernet interface is 802.3 (dot3). 

4.2.11 Forwarding IPX Broadcast Packet with Type 20 

Novell NetWare defines a type 20 IPX packet, used in NetBIOS (Network Basic 

Input/Output System). By default, this type 20 broadcast packet will be discarded by a 

router. However, users can permit to send type 20 broadcast packet to other network 

segment through configuring a command. 


Table 4-22 Forward IPX Broadcast Packet with Type 20 

Operation 

Permit to forward type 20 broadcast packet 

Prohibit forwarding type 20 broadcast packet 

Command 

ipx netbios-propagation 

undo ipx netbios-propagation 

4.3 Displaying and Debugging IPX 

I. Displaying and debugging IPX 

After the above configuration, execute the display command in all views to display the 

running of IPX configuration, and to verify the effect of the configuration. 

Execute the debugging command in user view for the debugging of IPX. 

Table 4-23 Display and debug IPX 

Operation 

Display interface status and 

interface parameters of IPX 

Display type and quantity of 

packets received and transmitted 

Display IPX service information 

table 

Display IPX active routing 

information 

Command 

display ipx interface [ interface-type 


display ipx statistics 

display ipx service-table [ [ type service-type 

| name name | network network | order 

{ network | type } ] | [ inactive ] ] [ verbose ] 

display ipx routing-table 

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Operation 

Display verbose IPX routing 

information, including active and 

inactive 

Display IPX routing statistics 

Display IPX active routing 

information with specified 

destination network ID 



destination network ID, including 

active and inactive 

Display IPX routing information 

with specified destination type 



destination type, including active 

and inactive 

Enable IPX SAP packet and 

event debugging switch 

Disable IPX SAP debugging 

switch 

Enable IPX packet debugging 

switch 

Disable IPX packet debugging 

switch 

Enable IPX ping debugging 

switch 

Disable IPX ping debugging 

switch 

Enable IPX RIP debugging 

switch 

Disable IPX RIP debugging 

switch 

Enable routing update debugging 

of the IPXRM module. 

Enable interface change 

debugging of the IPXRM module. 

Enable route change debugging 

of the IPXRM module. 


Command 

display ipx routing-table verbose 

display ipx routing-table statistics 

display ipx routing-table network 

display ipx routing-table network verbose 

display ipx routing-table protocol { default | 

direct | rip | static } [ inactive ] 

display ipx routing-table protocol { default | 

direct | rip | static } verbose 

debugging ipx sap [ packet [ verbose ] | 

event ] 

undo debugging ipx sap [ packet [ verbose ] 

| event ] 

debugging ipx packet [ interface-type 


undo debugging ipx packet [ interface-type 


debugging ipx ping 

undo debugging ipx ping 

debugging ipx rip { packet [ verbose ] | 

event } 

undo debugging ipx rip { packet [ verbose ] | 

event } 

debugging ipx rtpro-flash 

debugging ipx rtpro-interface 

debugging ipx rtpro-routing 

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II. Clear IPX statistics 

Perform the following configuration in user view. 

Table 4-24 Clear IPX statistics 

Clear IPX statistics 

Operation 

Clear statistics about the IPX routes of 

certain type. 

reset ipx statistics 

Command 

reset ipx routing-table statistics 

III. Check host reachability and network reachability 

Perform the following configuration in all views. 

Table 4-25 Check host reachability and network reachability 

Operation 

Check host reachability and network 

reachability 

Command 

ping ipx network.node [ -c count ] [ -t 

timeout ] [ -s size ] 

4.4 Typical Example of IPX Configuration 

4.4.1 Providing File Services and Directory Services through IPX Network 

I. Networking requirement 

Router A and B are connected using serial interfaces through an IPX network. The 

node address of Ethernet interface of Router A is 00e0-fc01-0000 and that of Router B 

is 00e0-fc01-0001. 

Here, Server is installed with NetWare 4.1 and its network ID is 2. Packet encapsulation 

format is Ethernet_II. Client is the user PC and its network ID is 3. Packet encapsulation 

format is SNAP. Server provides file services and directory services. Client can access 

these services through IPX network. The node of Server is 0000-0c91-f61f. 

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Router A 

Serial1/0/0 

1000.e0-fc01-0 

Ethernet2/0/0 

2.00e0-fc01-0000 

Hub 

Router B 

Serial1/0/0 

1000.e0-fc01-1 

Ethernet2/0/0 

3.00e0-fc01-0001 

Hub 

Server 

Client 

Figure 4-3 Network diagram for IPX configuration 


Configure Router A: 

# Activate IPX. 

[H3C] ipx enable 

# Activate IPX on the interface Ethernet2/0/0, with the network ID being 2. 


[H3C-Ethernet2/0/0] ipx network 2 

# Set the packet encapsulation format on Ethernet interface to Ethernet_II. 

[H3C-Ethernet2/0/0] ipx encapsulation ethernet-2 

[H3C-Ethernet2/0/0] quit 

# Activate IPX on the interface Serial1/0/0, with the network ID being 1000. 


[H3C-Serial1/0/0] ipx network 1000 

[H3C-Serial1/0/0] quit 

Configure Router B: 

# Activate IPX. 

[H3C] ipx enable 

# Activate IPX on the interface Ethernet2/0/0, with the network ID being 3. 


[H3C-Ethernet2/0/0] ipx network 3 

# Set packet encapsulation format on Ethernet interface to Ethernet_SNAP. 

[H3C-Ethernet2/0/0] ipx encapsulation snap 


# Activate IPX on the interface Serial1/0/0, with the network ID being 1000. 

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[H3C-Serial1/0/0] ipx network 1000 

[H3C-Serial1/0/0] quit 

# Configure a Server file service information item. 

[H3C] ipx service 4 server 2.0000-0c91-f61f 451 hop 2 

# Configure a Server directory service information item. 

[H3C] ipx service 26B tree 2.0000-0c91-f61f 5 hop 2 

[H3C] ipx service 278 tree 2.0000-0c91-f61f 4006 hop 2 

Since configuring the ipx network command on IPX interfaces also enables RIP and 

SAP, you do not need to configure routing protocol in this example. 

4.5 Troubleshooting IPX 

4.5.1 Troubleshooting IPX Core Layer 

Fault 1: IPX can not go UP on PPP link. 

Troubleshooting: 

• Confirm whether network IDs of both ends of the link are the same. Reconfigure 

them if they are different. 

• Confirm whether node IDs of both ends of the link are different. Reconfigure them 

if they are the same. 

Fault 2: Fail in pinging destination address. 


• Confirm whether the Ping destination address is correct. 

• Use the display ipx interface command to check the interface configuration on 

routers. The network ID and IPX frame encapsulation format of connected 

interfaces must be same. 

• Use the display ipx routing-table command to display routing information. Check 

whether the destination network ID is reachable. 

• Enable IPX packet debugging switch using the debugging ipx packet command. 

According to the detailed information displayed about IPX packets received, 

transmitted, forwarded and discarded, you can locate the error. 

Fault 3: Packets are discarded. 


• If IPX packet debugging information displays a packet is discarded, and the 

prompt is “Packet size is greater than interface MTU!”, it indicates the output 

packet size is greater than the maximum packet size the interface can transmit. 

Please use the display interface command to check the interface MTU and use 

the display ipx interface command to check the RIP and SAP packet size. If RIP 

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or SAP packet size is greater than interface MTU, RIP or SAP packet can not be 

sent out this interface. 

Fault 4: SAP packet can not be received by a router. 


• Use the display ipx interface command to check the receiving interface 

configuration. If SAP is disabled for this interface, SAP packet received from this 

interface will be discarded. 

Fault 5: IPX type 20 packet can not be transmitted to other network segment. 


• Use the display ipx interface command to check whether forwarding function of 

IPX type 20 packet is enabled on the receiving and transmitting interface. If it is not 

enabled, IPX type 20 packet can not be forwarded. 

• Enable IPX packet debugging switch using the debugging ipx packet command. 

If the debugging information displays that the type 20 packet is discarded and the 

prompt is “Transport Control field of IPX type-20 packet >= 8!”, it indicates IPX type 

20 packet can only be forwarded 8 times. If the packet has already been forwarded 

8 times it will not be forwarded further. 

4.5.2 Troubleshooting IPX RIP 

Fault 1: Route cannot be learnt from peer router. 


• Enable IPX RIP debugging switch using the debugging ipx rip packet verbose 

command. Check whether there is RIP packet with route sent form peer router. If 

there is not, there exist problems on the lower layer connection of the two routers. 

• If there is RIP packet with routing information sent form peer router, use the 

debugging ipx rip event command to see whether the received route is added 

into the routing table. If it is not, it indicates there are faults when adding route into 

the routing table. 

Fault 2: A configured static route is imported to RIP, but no static route is sent out. 


• Use the display ipx routing-table command to check whether static route has 

been configured. 

• If no configured static route is shown in routing table, use the display ipx 

routing-table verbose command to check whether there is an inactive route. If 

there is, check further why it is in inactive status. When the route becomes active, 

it can be advertised as an RIP route. 

• If configured static route is shown in routing table, continue to check its hop. If hop 

is more than or equal to 15, it is normal that no static route is sent out. 

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Note: 

Imported static route to RIP is active. Inactive static route cannot be imported or even 

sent out. There is a special route in static route, i.e., default route. Importing default 

route to RIP, users can also use ipx rip import-route static command, while the 

premise is that the default route must be active. 

On processing the route with hop being 15: 

When a router receives a route with hop being 15, it will send out the route for once with 

unreachable attribute. Since RIP regards the maximum reachable hop is 15, the route 

with hop being or more than 16 is unreachable route. When receiving a route with hop 

being 15, a router should plus 1 to the hop to make hop to 16 if it sends the route out, 

i.e., to make the route unreachable. This route makes no sense to the peer, so RIP only 

sends this route with unreachable attribute for once. 

Note that it is the same for the processing of the imported static route. Because hop 

cannot be configured in the ipx rip import-route static command which imports static 

route, the hop of original static route will be regarded as that of the imported RIP route. 

If a static route with hop being 15 is imported, it may cause that RIP stops sending 

routes after it sends the route with hop being 16 for once. 

4.5.3 Troubleshooting IPX SAP 

Fault 1: Unable to add static service information to SIT 


Verify with the display ipx service-table inactive command to see whether service 

information is added to inactive service information table. If it is, it indicates that there is 

no active route to destination server. 

Fault 2: No service information item in SIT. 


• Verify with the display ipx service-table inactive command to see whether 

service information is added to inactive service information table. If it is, it indicates 

that there is no active route to destination server. 

• Check with the display ipx interface command to see whether the interface is UP 

and SAP is enabled. 

• Check with the display ipx routing-table to verify that there is active route to the 

server with hop less than 15. 

• Another possible reason is that there is not sufficient memory to add a service 

information item to SIT in the system. Users can try to add static service 

information item. 

Fault 3: No new dynamic service information item in SIT. 

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• Use the debugging ipx packet and debugging ipx sap packet verbose 

commands to check whether related packet is received. If no packet is received, 

there might exist problems in lower layer network connection. 

• IPX disabled: Execute the ipx enable command in system view to enable IPX. 

• IPX interfaces not configured: Check with the display ipx interface command to 

make sure that IPX is configured on related interfaces. 

• SAP disabled: Use the undo ipx sap disable command to enable SAP on related 

interfaces. 

• Number of SAP service information items exceeds the limitation: Check that the 

number of SAP service information items has exceeded the limitation. IPX can 

support 10240 service information items with 5120 service types. 

• Interface MTU does not match: MTU configured by SAP should be less than or 

equal to physical layer MTU. 

Fault 4: Updating packet is not received on an interface. 


• Use the debugging ipx packet and debugging ipx sap packet verbose 

commands to check packet contents. Every incoming and outgoing packet is 

displayed with debugging information. If no related packet is displayed, there 

might exist problems in lower layer network connection. 

• Use the display ipx interface command to check whether SAP is enabled on an 

interface. 

• Check the route to the server to make sure active route hop to the router is less 

than 16. 

• Use the display current-configuration command to check whether the updating 

interval is too long. 

• Use the display current-configuration command to check whether an interface 

is configured with trigger update. In that case periodical updating packets will not 

be generated by those interfaces. 

Fault 5: Updating packet is not sent out an interface. 


• SAP MTU is more than physical layer MTU: Use the debugging ipx packet and 

debugging ipx sap packet verbose commands to check packet contents. If 

packet is displayed in debugging information, it is probably that SAP MTU is more 

than the interface MTU so the packet is discarded by the lower layer. 

• Use the display current-configuration command to check whether an interface 

is configured with trigger update. In that case periodical updating packets will not 

be generated by those interfaces. 

• If no SAP packet is sent out an interface, check whether all service information is 

learnt from the interface. It is probably that no service information is sent out the 

interface due to split horizon. 

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Fault 6: SAP does not respond to GNS request. 

Trouble shooting: 

• Use the debugging ipx packet sap command to check whether the router 

receives GNS request packet. 

• Check whether SAP is enabled on the interface which receives GNS packet. 

• Use the display ipx interface command to check whether GNS reply is disabled 

on the input interface. If it is, execute the undo ipx sap gns-disable-reply 

command to enable GNS reply. 

• Use the display ipx service-table command to see whether there is any service 

information complying with the request type in SIT. If there is not, SAP will not 

respond. 

• If there is service information complying with the request type in SIT and SAP does 

not respond, check whether the service information is learnt from the interface 

which receives the request. In that case SAP will also not respond to GNS request. 

Fault 7: SAP does not respond to GNS request in Round-robin method. 


• Use the display current-configuration command to check whether Round-robin 

method is configured. 

• If GNS Round-robin is configured, verify whether there are multiple equivalent 

service information items for the service type of the request. SAP considers they 

are equivalent service information items only when their RIP ticks, RIP hops, SAP 

hops and SAP preferences are the same. 

4.5.4 IPX Routing Management Troubleshooting 

Fault 1: The router dose not configure dynamic routing protocol. The interface physical 

status and link layer protocol status are both UP, but IPX packet can not be forwarded 

normally. 


• Use the display ipx routing-table protocol static command to check whether 

related static route is configured correctly. 

• Use the display ipx routing-table command to check whether static route has 

taken effect, and whether the next hop address is not specified or not correct on 

non PPP interface. 

Fault 2: The local router receives a route sent from a neighbor router, but the route can 

not be found on the local router using the display ipx routing-table verbose 

command. 


• Use the display current-configuration command to check whether the 

maximum dynamic route number is configured under each destination network ID, 

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with the corresponding command ipx route max-reserve-path. If it is not 

configured, the default value 4 is used. 

• Use the display ipx routing-table verbose command to check the existing 

dynamic route number under the destination network ID (only RIP route is 

dynamic route at present). 

If the dynamic route number under the destination network ID in the current system has 

exceeded the maximum value configured, the newly received routes will not be added 

to the routing table. The solution is to use the ipx route max-reserve-path command 

to adjust the maximum number of dynamic route a little bit larger. 

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Chapter 5 DLSw Configuration 


5.1 DLSw Overview 

5.1.1 Introduction 

Data link switching (DLSw) is a system network architecture (SNA) trans-WAN 

transmission solution. It was developed by Advanced Peer-to-Peer Networking (APPN) 

Implementers Workshop (AIW) to transmit SNA, a network protocol developed by IBM 

in correspondence to the OSI reference model in 1970s, over TCP/IP. 

The DLSw performance mechanism is shown in the following figure: 

LAN 

LLC2 

TCP/IP 

LAN 

LLC2 

End System 

DLSw 

SSP 

DLSw 

End System 

Figure 5-1 DLSw mechanism diagram 

As shown above, the frame in LLC2 format of local SNA device is transformed into SSP 

frame encapsulated in TCP packet by the router running the DLSw protocol. Across 

WAN through TCP connection, it is forwarded to remote end, where the SSP frame is 

retransformed into related LLC2 frame and forwarded to the remote SNA device. 

Obviously, the DLSw makes the local terminal equipment “believe” that the remote 

device is in the same network with it. Different from the transparent bridge, however, 

the DLSw does not transparently transmit the previous LLC2 frame directly to the peer 

end. Rather, it transforms the LLC2 frame into SSP frame to achieve the encapsulation 

in TCP packet of the previous data. By virtue of its local response mechanism, the 

DLSw can reduce unnecessary data transmission (confirming frame and keeping 

active frame), and tackle the problem of data link control timeout. 

With DLSw, you can implement trans-TCP/IP transmission of synchronous data link 

control (SDLC). To this end, you need first to convert an SDLC packet into a logical link 

control, type 2 (LLC2) packet, and then to interconnect with the remote end through 

DLSw. Thus, DLSw can interconnect different media between LAN and SDLC. 

Currently, DLSw has two versions: DLSw 1.0 and DLSw 2.0. DLSw 1.0 is implemented 

based on RFC1795, while DLSw 2.0 is based on RFC2166 and is intended to improve 

product maintainability and to reduce network cost. In addition, DLSw 2.0 is enhanced 

by the function of sending UDP explorers in multicast and unicast modes. When the 

peer is also running DLSw 2.0, the two ends can use UDP packets to explore 

reachability, and are allowed to establish the TCP connection only when required for 

data transmission. 

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5.1.2 Differences between DLSw1.0 and DLSw2.0 

The following subsections cover the problems with DLSw1.0. 

I. TCP connection 

In DLSw1.0, immediately after a pair of peers is configured, the local peer attempts to 

establish TCP connection with the remote peer by first establishing two uni-directional 

TCP connections and bringing down one of them after capabilities exchange, 

disregarding whether circuit setup is needed or not. All packets, including explorers, 

circuit setup requests, and data packets, are transferred over TCP connection. This 

somewhat wastes network resources. 

II. Excessive broadcasts 

Although a local acknowledgement mechanism is available with DLSw1.0, probe 

packets may flood the WAN over the established TCP connections if the reachability 

table of DLSw contains no or too few entries. 

III. Low maintainability 

When a circuit is disconnected, DLSw1.0 uses two types of packets to notify the peer 

but cannot tell the disconnection cause. It is very hard for maintenance personnel to 

determine the real cause when there is an abnormal circuit disconnection. 

DLSw2.0 was thus developed to deal with the above-mentioned problems while being 

compatible with DLSw1.0. 

The following are the new functions that DLSw2.0 implements based on DLSw1.0: 

For illustration sake, the components on a DLSw network are defined as follows: 

Origin 

station 

LAN 

Origin 

DLSw router 

UDP, TCP/IP 

SSP packet 

Target 

DLSw router 

LAN 

Target 

station 

Figure 5-2 DLSw2.0 network 

These components are defined as follows: 

• Origin station: the endstation that originates communication 

• Target station: the endstation that accepts communication 

• Origin DLSw/DLSw2.0 router: the DLSw-enabled or DLSw2.0-enabled router 

connected to the origin station 

• Target DLSw router: the DLSw-enabled router connected to the target station 

IV. UDP packets for exploying peer addresses 

To prevent unnecessary TCP connection setups, DLSw2.0 sends explorer frames by 

using UDP packets (unless a TCP connection is present) instead of over TCP 

connection. These UDP packets can be sent in two ways: multicast and unicast. 

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V. Setting up single-session TCP conneciton on demand 

After the origin and target DLSw2.0 routers get reachability information by using UDP 

packets, they do not set up TCP connection immediately. Instead, they do that only 

when origin and target stations want to set up a circuit between them. The TCP 

connection setup process may be simplified into two stages: 

1) Establishing a single TCP connection 

2) Capabilities exchange. If capabilities negotiation fails, the DLSw2.0 router sends a 

reject packet to the peer and then the TCP connection is disconnected. 

As TCP connection is established in response to circuit setup request, the overheads of 

establishing and maintaining TCP connections are reduced and system resource 

utilization is improved as a result. 

Note: 

In case the origin and target DLSw routers use different versions of DLSw, the one uses 

DLSw2.0 considers itself as a DLSw1.0 router and follows RFC1795 when setting up a 

TCP connection with its peer for backward compatibility. 

VI. Ehanced maintainability 

DLSw2.0 adds reason code fields for notifying circuit halt causes. It defines five generic 

circuit halt reason codes: unknown error, received DISC from endstation, detected DLC 

error with endstation, circuit-level protocol error, and operator-initiated. 

5.1.3 Associated Protocols 

The implemented DLSw protocols include: 

• RFC1795: Data Link Switching: Switch-to-Switch Protocol 

• RFC2166: DLSw v2.0 Enhancements 

5.2 DLSw Configuration 

The DLSw configuration includes: 

1) Configure DLSw in an Ethernet environment 

Following are the basic configuration tasks: 

• Enable bridging and bridge-set 

• Enable/suspend DLSw 

• Create the local DLSw peer 

• Create the remote DLSw peer 

• Configure the bridge group connected with the DLSw 

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• Configure the Ethernet interface to join into a bridge group 

Following are optional configuration tasks: 

• Configure the DLSw timer 

• Configure the ahead response window of LLC2 

• Configure the local response window of LLC2 

• Configure the queue length sending LLC2 packet 

• Configure the modulus of LLC2 

• Configure retransmission of LLC2 

• Configure local response delay of LLC2 

• Configure local response time of LLC2 

• Configure BUSY time of LLC2 

• Configure the P/F waiting time of LLC2 

• Configure the REJ status time of LLC2 

Following are DLSw2.0 enhancements: 

• Enable the multicast function of DLSw2.0 

• Configure explorer frame retransmission 

2) Configure DLSw in an SDLC environment 

Following are the basic configuration tasks: 

• Enable bridging and bridge-set 

• Enable/suspend DLSw 

• Encapsulate the interface with the link layer protocol SDLC 

• Configure the SDLC peer 

• Configure the bridge group connected with the DLSw 

• Add the SDLC synchronous serial port to a bridge group 

• Configure SDLC role 

• Configure the SDLC address 

• Configure the XID of SDLC (required for PU2.0 devices) 

• Configure the SDLC virtual MAC address 

Following are optional configuration tasks: 

• Configure the baud rate of the synchronous serial port 

• Configure the coding scheme of the synchronous serial port 

• Configure the idle coding scheme of the synchronous serial port 

• Configure the output-queue length of SDLC 

• Configure the local response window of SDLC 

• Configure the modulus of the SDLC 

• Configure the maximum frame length of SDLC 

• Configure retransmission of SDLC 

• Configure the SAP address on transforming the SDLC into LLC2 

• Configure the two-way data transmission mode of SDLC 

• Configure the poll pause timer of SDLC 

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• Configure the primary response waiting time of SDLC 

• Configure the secondary response waiting time of SDLC 

5.2.1 Enabling Bridging and Bridge-Set 


Table 5-1 Enable/disable bridging 

Enable bridging. 

Disable bridging. 

Operation 

bridge enable 

Command 

undo bridge enable 

Table 5-2 Configure a bridge-set 

Operation 

Enable a bridge-set. 

Delete a bridge-set. 

Command 

bridge bridge-set enable 

undo bridge bridge-set enable 

For complete information, refer to the chapter discussing bridging in the “Link Layer 

Protocol” part of this manual. 

5.2.2 Creating the Local DLSw Peer 

Setting up TCP connection is critical to DLSw connection setup. When setting up a TCP 

connection, you must specify the IP addresses at both ends of the TCP connection. You 

can specify the local IP address for TCP connection setup by configuring the local 

DLSw peer. Only after the configuration of this command can the TCP connection 

request initiated by the remote router be accepted. A router can only have one local 

peer. 

Perform the following command in system view. 

Table 5-3 Create the local DLSw peer 

Operation 

Create the local DLSw peer 

Delete the local DLSw peer 

or restore the default value 

of parameters 

Command 

dlsw local ip-address [ init-window 

init-window-size ] [ keepalive keepalive-interval ] 

[ max-frame max-frame-size ] [ max-window 

max-window-size ] [ permit-dynamic ] 

undo dlsw local ip-address [ init-window ] 

[ keepalive ] [ max-frame ] [ max-window ] 

[ permit-dynamic ] 

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The dlsw local command is to be configured before other commands on the DLSw 

configuration. Among them, the IP addresses are required and the configured IP 

addresses must be reachable host IP address. Concerning the undo dlsw local 

command with only local parameter, it is used to delete the local peer. As for the case 

that it carries other parameters, it indicates to restore the default value of the specified 

parameters. 

5.2.3 Creating the Remote DLSw Peer 

After the local peer is configured, the remote DLSw peer should be configured to create 

the TCP connection. This command specifies the IP address that the remote router 

used to create the TCP connection. After the configuration, the router will keep 

attempting to connect with the remote router. A router may have many remote peers. 

By configuring several remote peers, the TCP connection can be created with many 

remote routers. 


Table 5-4 Create the remote DLSw peer 

Operation 

Create the remote 

DLSw peer 

Delete the remote 

DLSw peer 

Command 

dlsw remote ip-address [ backup backup-address ] [ acl 

acl-number ] [ priority priority] [ keepalive keepalive-interval ] 

[ max-frame max-frame-size ] [ max-queue 

max-queue-length ] [ linger minutes ] 

undo dlsw remote ip-address 

In the table, the IP addresses are required. The configured IP address must be the IP 

address of the reachable remote DLSw router. 

5.2.4 Configuring the Bridge-set Group Connected with DLSw 

The DLSw technique is developed based on bridge technology. Bridge group is the 

forwarding unit of the bridge. Many different Ethernet interfaces can be configured in 

the same bridge-set group so that they can forward packets to each other. In order to 

forward the packet in the bridge group to the remote end through TCP connection, this 

command is need to connect a local bridge group to the DLSw, that is, the packets of 

this local bridge group can be sent to the remote end through the TCP connection. This 

command can be used many times to connect many bridge groups with the DLSw, so 

that all of them can perform forwarding through the TCP connection. 

Note that you must enable bridging and bridge-set before configuring this command. 


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Table 5-5 Configure the bridge-set connected with the DLSw 

Operation 

Configure the bridge-set connected 

with the DLSw 

Remove the bridge-set connected 

with the DLSw 

Command 

dlsw bridge-set bridge-set-number 

undo dlsw bridge-set bridge-set-number 

By default, the bridge-set connected with the DLSw is not configured. 

5.2.5 Configure Timer Parameters of DLSw 

Various kinds of timer values, used by the DLSw to create virtual circuits, can be 

revised by configuring the timer of the DLSw protocol. 


Table 5-6 Configure the timer of the DLSw protocol 

Operation 

Configure timer parameters of 

DLSw 

Restore the default value of the 

parameters of the DLSw time 

Command 

dlsw timer { connected | explorer-wait | 

local-pending | remote-pending | cache | 

explorer } seconds 

undo dlsw timer { connected | explorer-wait | 

local-pending | remote-pending | cache | 

explorer } 

By default, the connect seconds is 300 seconds, the explorer-wait seconds is 30 

seconds, the local-pending seconds is 30 seconds, the remote-pending seconds is 

30 seconds, the cache seconds is 120 seconds, and the explorer seconds is 30 

seconds. 

It is not suggested to modify the DLSw timer parameters under normal circumstances. 

5.2.6 Configuring to Enable/Suspend the DLSw Performance 


Table 5-7 Configure to suspend the DLSw performance 

Operation 

Command 

Enable the DLSw performance 

Suspend the DLSw performance 

dlsw enable 

undo dlsw enable 

By default, the DLSw performance is enabled. 

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After the undo command is performed, the system will release all dynamic resources, 

but reserve the original configuration. 

5.2.7 Configuring the Ethernet Interface to Join into a Bridge-Set 

In order to add the Ethernet interface to a bridge-set, this command is required to 

confirm which bridge-set is to be added into. Use this command in concert with the 

above command, and so the LLC2 packet on the Ethernet interface can be forwarded 

to the TCP connection and sent to the remote peer. 

Perform the following command in Ethernet interface view. 

Table 5-8 Add the Ethernet interface to a bridge-set 

Operation 

Add the Ethernet interface to a bridge-set 

Command 

bridge-set bridge-set-number 

Remove the bridge-set that the Ethernet 

interface is added to 

undo 

bridge-set-number 

bridge-set 

By default, no Ethernet interface is added to the bridge-set. The bridge-set-number 

indicates the number of bridge-set. In order that this interface can perform the DLSw 

forwarding, this command should be used in concert with the above command(dlsw 

bridge-set). In other words, the same number of bridge-sets should be specified. 

5.2.8 Configuring the Ahead Response Window of LLC2 

The LLC2 ahead response window refers to the maximum number of receivable 

information frames before the acknowledgement frame is sent. In other words, the 

response packet will be forwarded to the opposite side in advance before the packet “n” 

is received. 


Table 5-9 Configure the ahead response window of LLC2 

Operation 

Configure the ahead response window of LLC2 

Restore the length of LLC2 ahead response 

window to the default value 

Command 

llc2 max-ack length 

undo llc2 max-ack 

By default, the size of LLC2 ahead response window is 3. 

5.2.9 Configuring LLC2 Local Response Window 

The LLC2 local response window refers to the maximum number of packets that can be 

sent continuously before receiving the acknowledge frame. 

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Table 5-10 Configure the LLC2 local response window 

Operation 

Configure the LLC2 local response window 

Restore the default value of the length of the 

LLC2 advanced response window 

Command 

llc2 receive-window length 

undo llc2 receive-window 

By default, the length of the LLC2 local response window is 7. 

5.2.10 Configuring the Queue Length Sending the LLC2 Packet 


Table 5-11 Configure the queue length sending the LLC2 packet 

Operation 

Configure the queue length sending the LLC2 

packet 

Restore the default value 

Command 

llc2 max-send-queue length 

undo llc2 max-send-queue 

By default, the queue length sending the LLC2 packet is 50. 

5.2.11 Configuring the Modulus of LLC2 

Same as the X25 protocol, the LLC2 uses the modulo approach to packet numbering, 

with the modulus being 8 or 128. The Ethernet generally adopts the modulus 128. 


Table 5-12 Configure the module value of LLC2 

Operation 

Configure the modulus of LLC2 

Restore the default value of LLC2 

llc2 modulo n 

Command 

undo llc2 modulo 

By default, the modulus of LLC2 is 128. 

5.2.12 Configuring Number of Transmission Retries of LLC2 

The LLC2 transmission retries are attempts to send a frame before an acknowledge 

frame is received from the peer end. 


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Table 5-13 Configure number of transmission retries of LLC2 

Operation 

Configure the number of transmission 

retries of LLC2 

Restore the default number of 

transmission retries of LLC2 

Command 

llc2 max-transmission retries 

undo llc2 max-transmission 

The default number of transmission retries of LLC2 is three. 

5.2.13 Configuring Local Response Delay Time of LLC2 

The SNA transmits LLC2 packets over Ethernet. Some working parameters can be 

revised by configuring the LLC2 related commands. 

The LLC2 local response delay time refers to the maximum delay time to wait for 

responding the received LLC2 data packets. 


Table 5-14 Configure local response delay time of LLC2 

Operation 

Configure local response delay time of 

the LLC2 

Restore the default value of LLC2 local 

response delay time 

Command 

llc2 timer ack-delay mseconds 

undo llc2 timer ack-delay 

By default, the LLC2 local response delay time is 100ms. 

5.2.14 Configuring Local Response Time of LLC2 

The LLC2 local response time refers to the maximum waiting time for the response 

from the peer end after sending an LLC2 data packet. 


Table 5-15 Configure local response time of LLC2 

Operation 

Configure local response time of LLC2 

Restore local response time of LLC2 to 

the default value 

Command 

llc2 timer ack mseconds 

undo llc2 timer ack 

By default, the LLC2 local response time is 200ms. 

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5.2.15 Configuring BUSY Time of LLC2 

The LLC2 BUSY time refers to the waiting time before re-polling a busy site. 


Table 5-16 Configure BUSY time of LLC2 

Operation 

Configure BUSY time of LLC2 

Restore the default LLC2 BUSY time 

Command 

llc2 timer busy mseconds 

undo llc2 timer busy 

By default, the LLC2 BUSY time is 300ms. 

5.2.16 Configuring the P/F Waiting Time of LLC2 

The LLC2 Poll/Final (P/F) waiting time refers to the time of waiting for the acknowledge 

frame after sending the P frame. 


Table 5-17 Configure the P/F waiting time of LLC2 

Operation 

Configure the P/F waiting time of LLC2 

Restore the default LLC2 P/F waiting time 

Command 

llc2 timer poll mseconds 

undo llc2 timer poll 

5.2.17 Configuring the REJ Status Time of LLC2 

The REJ status time of the LLC2 refers to the time of waiting for the acknowledge frame 

after forwarding the reject frame. 


Table 5-18 Configure the REJ status time of LLC2 

Operation 

Configure the REJ status time of LLC2 

Restore the REJ status time of LLC2 to the default 

value 

Command 

llc2 timer reject mseconds 

undo llc2 timer reject 

By default, the REJ status time of LLC2 is 500ms. 

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5.2.18 Configuring DLSw Version and Filtering for a Remote DLSw Peer 


Table 5-19 Configure the DLSw version and filtering rule for a remote DLSw peer 

Operation 

Create a remote DLSw peer and specify 

its version and filtering rule 

Delete a remote DLSw peer 

Command 

dlsw remote ip-address [ version 

version-number | acl acl-num ] * 

undo dlsw remote ip-address 

By default, the DLSw version of remote peer is set to 1. 

5.2.19 Enabling the Multicast function of DLSw2.0 

Before enabling the multicast function of DLSw2.0, you need first to configure the 

multicast function of the router and the local DLSw peer. 

Only after DLSw2.0 is enabled can the origin DLSw2.0 router multicast SOCKET 

messages (with explorer frames encapsulated) to a specified multicast address. This 

allows all target DLSw routers listening to the multicast address to receive the SOCKET 

messages and get the explorer frames. 


Table 5-20 Enable the multicast function of DLSw2.0 

Operation 

Enable the multicast function of DLSw2.0 

Disable the multicast function of DLSw2.0 

Command 

dlsw 

multicast 

[ multicast-IP-address ] 

undo dlsw multicast 

By default, the multicast function of DLSw2.0 is disabled. If it is enabled, the default 

multicast address is 224.0.10.0. 

Caution: 

On Routers, DLSw2.0 is enabled with multicast disabled by default. To use DLSw 

multicast, you need to execute the dlsw multicast command. 

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5.2.20 Configuring Explorer Frame Retransmission 

Each time the origin DLSw2.0 router sends an explorer frame in a UDP multicast or 

unicast packet, an explorer timer starts. If no response is received before the explorer 

timer times out, the router retransmits the explorer frame and restarts the explorer timer. 

If no response packet is received after the maximum number of explorer frame sending 

attempts are made, the router stops sending attempt. 


Table 5-21 Set the maximum number of attempts to send an explorer frame 

Operation 

Set the maximum number of attempts to 

send an explorer frame 

Restore the default maximum number of 

attempts to send an explorer frame 

Command 

dlsw max-transmission retries 

undo dlsw max-transmission 

By default, the maximum number of attempts to send an explorer frame is five. 

5.2.21 Configuring to filter packets from Peers 


Table 5-22 Configure to filter packets from peers 

Operation 

Configure to filter packets from peers 

Disable filtering of packets from peers 

Command 

dlsw filter acl acl-number 

undo dlsw filter acl acl-number 

5.2.22 Configuring SDLC to be the Link Layer Protocol Encapsulated in an 

Interface 

The SDLC is a kind of link layer protocol relative to the SNA, with working principle 

similar to that of HDLC. In order that the DLSw can work normally, the encapsulated link 

layer protocol of the synchronous serial port should be changed into the SDLC. 

Perform the following configuration in synchronous serial port view. 

Table 5-23 Configure the link layer protocol encapsulated in an interface as SDLC 

Operation 

Configure the link layer protocol encapsulated in 

an interface as SDLC 

Command 

link-protocol sdlc 

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By default, the link layer protocol encapsulated in the synchronous serial port is PPP. 

It is important to note that: the SDLC link layer protocol cannot be used to carry IP 

protocol, so all the commands related to the IP on the interface should be removed 

before encapsulating the SDLC, for example, deleting the IP address on the interface, 

etc. 

5.2.23 Adding the SDLC Encapsulated Synchronous Serial Port to a 

Bridge-Set 

This command is used to add the SDLC interface to a bridge-set so that the SDLC 

encapsulated interface can perform the DLSw forwarding. What is different is that the 

bridge-set on the Ethernet interface practices local forwarding, whereas the bridge-set 

configured on the SDLC only practices DLSw forwarding, that is, the data in the 

bridge-set will be forwarded to the TCP connection. 

Perform the following command in synchronous serial port view. 

Table 5-24 Add the synchronous serial port to a bridge-set 

Operation 

Add the synchronous serial port to a bridge-set 

Command 

bridge-set bridge-set-number 

Remove the bridge-set added with the 

synchronous serial port 

undo 

bridge-set-number 

bridge-set 

5.2.24 Configuring the Baud Rate of the Synchronous Serial Port 

The commands above are some basic commands for configuring the DLSw. In real 

circumstances, there are various kinds of SNA devices that differ greatly. The following 

commands are some often used adjustment parameters compatible to different 

devices. 


Table 5-25 Configure the baud rate of the synchronous serial port 

Operation 

Configure the baud rate of the synchronous serial port 

Restore the baud rate of the synchronous serial port to 


Command 

baudrate baudrate 

undo baudrate 

By default, the baud rate of the synchronous serial port is 64000pbs, and that of the 

SNA device serial port is 9600bps. 

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5.2.25 Configuring the Coding Scheme of the Synchronous Serial Port 

There are two kinds of coding schemes, NRZI and NRZ, on the synchronous serial port. 

NRZ coding scheme is generally adopted by default. The serial port coding scheme of 

some SNA devices is NRZI coding. Thus the coding of routers should be changed 

according to the coding schemes of the connected devices. 


Table 5-26 Configure the coding scheme of the synchronous serial port 

Operation 

Configure the NRZI coding scheme of the synchronous 

serial port 

Remove the NRZI coding scheme of the synchronous 

serial port 

code nrzi 

undo code 

Command 

By default, the NRZ coding scheme is adopted on the synchronous serial port. 

5.2.26 Configuring the Idle Coding Scheme of the Synchronous Serial Port 

The SDLC serial port of routers is generally marked by “7E” in idle time. Some SDLC 

devices, however, adopt full “1” high level working status. In order to be better 

compatible to these devices, the idle coding scheme of the routers needs to be 

changed. 


Table 5-27 Configure the idle coding scheme of the synchronous serial port 

Operation 

Configure the idle coding scheme of the synchronous 

serial port 

Restore the default coding scheme of the synchronous 

serial port 

idle-mark 

Command 

undo idle-mark 

The idle coding scheme of the synchronous serial port commonly seldom needs to be 

changed. Sometimes on connection with AS/400, this command needs to be 

configured to change the idle coding scheme to quicken the AS/400 poll rate. 

5.2.27 Configuring the SDLC Role 

In contrast with the HDLC, the SDLC is a kind of link layer protocol in unbalanced mode. 

That is, the statuses of the devices on the two connected ends are opposite: one is 

primary and the other is secondary. The primary side, being the primary station, whose 

role is primary, plays the dominant role and controls the whole connection process. 

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While the other side, being the secondary station, whose role is secondary, receives 

control passively. Therefore, we need to configure roles for the interfaces encapsulated 

with the SDLC protocol. 


Table 5-28 Configure the SDLC role 

Operation 

Command 

Configure the SDLC role sdlc status { primary | secondary } 

Remove the SDLC role undo sdlc status { primary | secondary } 

On the SDLC role configuration, the roles should be decided by the status of the SDLC 

device connected with the local router. If the SDLC device connected with the local 

router is primary, the local interface is to be set secondary, and vice versa. Normally, 

the central IBM mainframe is primary, while devices as UNIX hosts or ATM (Auto Teller 

Machine) are secondary. 

By default, no role is set. 

5.2.28 Configuring the SDLC Virtual MAC Address 

The DLSw, establishing map relations of virtual circuit through MAC address, is 

originally designed for the LLC2 typed protocols. Hence MAC address must be 

specified for the SDLC virtual circuit so that the SDLC packet can be forwarded. This 

command is used to assign to the interface a virtual MAC address, which is served as 

the source MAC address during the translation from SDLC packets to LLC2 packets. 


Table 5-29 Configure the SDLC virtual MAC address 

Operation 

Configure the SDLC virtual MAC address 

Remove the SDLC virtual MAC address 

Command 

sdlc mac-map local mac-address 

undo sdlc mac-map local 

By default, the SDLC has no virtual MAC address. 

Note the last byte of MAC address should be specified into 0x00. The system will 

combine the first five bytes of this virtual MAC address with the SDLC address into a 

new MAC address to serve as the local MAC address used for LLC2 translation. 

5.2.29 Configuring the SDLC Address 

The SDLC protocol permits several virtual circuits running on an SDLC physical link, 

with one end connected with the primary station and the other end connected with the 

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secondary station. In order to distinguish each virtual circuit, their SDLC addresses 

need to be designated. Because the SDLC is in unbalanced mode, a primary device 

uniquely connects with several secondary devices through the shared machine or the 

SDLC switch, while the secondary devices cannot be connected with each other. In this 

sense, the SDLC devices in the same group can be guaranteed to communicate with 

each other normally only if the addresses of the secondary devices are specified. This 

command specifies the SDLC address for virtual circuit, which is unique on a physical 

interface. The configured SDLC address on synchronous serial port is virtually the 

address of the SDLC secondary station. 


Table 5-30 Configure the SDLC address 

Operation 

Configure the SDLC address 

Remove the configured SDLC address 

Command 

sdlc controller sdlc-address 

undo sdlc controller sdlc-address 

The SDLC address ranges from 0x01 to 0xFE. The SDLC address of one router is only 

valid on one physical interface. That is, the SDLC addresses configured on different 

interfaces may be the same. 

5.2.30 Configuring the SDLC Peer 

This command is used to specify the MAC address of a peer end for an SDLC virtual 

circuit so as to provide the destination MAC address on the transformation from SDLC 

to LLC2. When configuring DLSw, a related peer should be configured for an SDLC 

address. The MAC address of the peer should be the MAC address of the remote SNA 

device (physical addresses of such devices as the Ethernet or the Token-Ring), or the 

MAC address of the peer end formed by the SDLC. 


Table 5-31 Configure the SDLC peer 

Operation 

Configure the SDLC peer 

Remove the SDLC peer 

Command 

sdlc mac-map remote mac-addr sdlc-addr 

undo sdlc mac-map remote mac-addr sdlc-addr 

It is of significance to note the difference of the byte order between the Token-Ring and 

the Ethernet. The address of the Token-Ring can be configured as it marked by the 

device. While on configuring the Ethernet, each byte should be reversed. For example, 

the MAC address of the Ethernet marked as 00e0.fc03.a548 should be configured as 

0007.3fc0.5a12. 

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By default, the synchronous serial port has no peer. 

5.2.31 Configuring the XID of SDLC 

The XID is used to identify the ID of a device in SNA. On configuring the SDLC 

connection, the type of the connected SNA device should be noted. Generally speaking, 

there are two kinds of devices: PU2.0 and PU2.1. The XID has been configured on the 

PU2.1 devices and they can announce their IDs by exchanging the XID. The PU2.0 

devices do not exchange the XID, neither do they have XID. Therefore, this command 

need not be configured on PU2.1 typed devices, while it is necessary to specify an XID 

for PU2.0 typed devices. 


Table 5-32 Configure the XID of SDLC 

Operation 

Configure the XID of SDLC 

Remove the XID of the configured SDLC 

Command 

sdlc xid sdlc-address xid-number 

undo sdlc xid sdlc-address 

By default, the XID of the SDLC is not configured on the synchronous serial port. 

5.2.32 Configure the Length of the Queue for Sending SDLC Packets 


Table 5-33 Configure the length of the queue for sending SDLC packets 

Operation 

Configure the length of the queue for 

sending SDLC packets 

Restore the queue length to the default value 

Command 

sdlc max-send-queue length 

undo sdlc max-send-queue 

By default, the length of the queue for sending SDLC packets is 50. 

5.2.33 Configuring the Local Response Window of SDLC 

The SDLC local response window refers to the maximum number of packets 

continuously sent without waiting for the response from the peer end. 


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Table 5-34 Configure the local response window of SDLC 

Operation 

Configure the local response window of SDLC 

Restore the default value 

Command 

sdlc window length 

undo sdlc window 

By default, the size of the SDLC local response window is 7. 

5.2.34 Configuring the Modulus of SDLC 

The same as the X25 protocol, the SDLC adopts a module method to coding 

information packets, with the modulus of 8 or 128. The SDLC generally adopts the 

modulus 8. 


Table 5-35 Configure the modulus of SDLC 

Operation 

Configure the modulus of the SDLC 

Restore the modulus of the SDLC to the default value 

Command 

sdlc modulo n 

undo sdlc modulo 

By default, the modulus of SDLC is 8. 

5.2.35 Configuring the Maximum Frame Length of SDLC 

The maximum frame length of the SDLC refers to the bytes of the largest packet that 

can be received and sent, excluding the parity bit and the start/stop bit. 


Table 5-36 Configure the maximum frame length of SDLC 

Operation 

Configure the maximum frame length of SDLC 

Restore the maximum frame length of SDLC to the 

default value 

Command 

sdlc max-pdu n 

undo sdlc max-pdu 

By default, the maximum frame length of SDLC is 265 bytes. 

The maximum frame length of some PU2.0 devices is of 265 bytes, and that of IBM 

AS/400 is generally of 521 bytes. Usually we need to configure it to the same value as 

the connected SDLC device. 

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5.2.36 Configuring the Number of Transmission Retries of SDLC 

You may configure SDLC to resend a packet multiple times before receiving an 

acknowledgement from the peer end. 

The number of the transmission retries discussed here includes the first transmission. 


Table 5-37 Configure the number of transmission retries of SDLC 

Operation 

Configure the number of transmission 

retries of SDLC 

Restore the default number of 

transmission retries of SDLC 

Command 

sdlc max-transmission retries 

undo sdlc max-transmission 

The default number of SDLC transmission retries is 20. 

5.2.37 Configuring the SAP Address on Transforming from SDLC to LLC2 

When transforming the SDLC packet into the LLC2 packet, the Service Access Point 

address is needed besides the MAC address. This command can specify the SAP 

address for an SDLC node on transforming LLC2. 


Table 5-38 Configure the SAP address on transforming from SDLC to LLC2 

Operation 

Configure the SAP address on 

transforming from SDLC to LLC2 

Restore the default value of the SAP 

address on transforming from SDLC 

to LLC2 

Command 

sdlc sap-map { local lsap | remote dsap } 

sdlc-addr 

undo sdlc sap-map { local lsap | remote 

dsap } sdlc-addr 

By default, both lsap and dsap of the LLC2 are 0x04. 

5.2.38 Configuring the Two-Way Data Transmission Mode of SDLC 

This command configures the synchronous serial port encapsulating SDLC protocol to 

work in two-way data simultaneous transmission mode. That is, the SDLC primary 

station can forward data to the secondary station while receiving data. 


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Table 5-39 Configure the two-way data transmission mode of SDLC 

Operation 

Configure the two-way data 

transmission mode of SDLC 

Cancel the SDLC data two-way 

transmission mode 

sdlc simultaneous 

Command 

undo sdlc simultaneous 

The default is the two-way alternate transmission mode. Generally speaking, this 

command need not be configured. 

5.2.39 Configuring the Poll Pause Timer of SDLC 

The poll pause timer of SDLC refers to the time interval to wait for the SDLC primary 

between polling two SDLC nodes. 


Table 5-40 Configure the poll pause timer of SDLC 

Operation 

Configure the poll pause timer of SDLC 

Restore the poll pause timer of SDLC to 


Command 

sdlc timer poll mseconds 

undo sdlc timer poll 

By default, the poll pause timer of SDLC is 1000ms. 

5.2.40 Configuring the Primary Response Waiting Time of SDLC 

The primary station response waiting time refers to the time that the primary station 

waits for the response from the secondary station after it sends the information frame. 


Table 5-41 Configure the response waiting time of SDLC 

Operation 

Configure the response waiting time of SDLC 

Restore the response waiting time of SDLC to the 

default value 

Command 

sdlc timer ack mseconds 

undo sdlc timer ack 

By default, the primary station response waiting time of SDLC is 3000ms. 

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5.2.41 Configuring the Secondary Response Waiting Time of SDLC 

The secondary station response waiting time refers to the time that the secondary 

station waits for the response from the primary station after it sends the information 

frame. 


Table 5-42 Configure the controlling frame response waiting time of SDLC 

Operation 

Configure the controlling frame 

response waiting time of SDLC 

Restore the default value of the 

secondary station response waiting time 

Command 

sdlc timer lifetime mseconds 

undo sdlc timer lifetime 

By default, the secondary station response waiting time of SDLC is 500ms. 

5.2.42 Configuring the local or remote reachability information 

To reduce the probe process before the router sends a packet, you may manually 

configure the reachability of the local end or the remote end when network topology is 

stable. 

Table 5-43 Configure the reachability of the local or remote end 

Operation 

Configure the reachable MAC address and SAP 

address of the local end 

Remove the configured reachability information 

Configure the reachability information of the 

remote end 

Remove the configured reachability information 

of the remote end 

Command 

dlsw reachable 

undo dlsw reachable 

dlsw reachable-cache 

undo dlsw reachable-cache 

5.3 Displaying and Debugging DLSw 

After the above configuration, execute the display command in all views to display the 

running of the DLSw configuration, and to verify the effect of the configuration. 

Execute the reset command in user views to clear the running. 

Execute the debugging command in user view for the debugging of DLSw 

configuration. 

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Table 5-44 Display and debug DLSw 

Operation 

Display the information of the interface 

bridge-set 

Display the capability exchange information 

Display the information of the virtual circuit 

Command 

display dlsw bridge-entry 

[ interface-type interface-number ] 

display dlsw information [ local ] 

[ ip-address ] 

display dlsw circuits [circuit-Id ] 

[ verbose ] 

Display the information of the remote peer display dlsw remote [ ip-address ] 

Display the reachable-cache of DLSw 

Display statistics about LLC2 

display dlsw reachable-cache 

display llc2 

Clear the information of the virtual circuit reset dlsw circuits [ circuit-id ] 

Clear the information of interface bridge-set 

Clear the reachable-cache of DLSw 

Enable DLSw debugging 

Disable DLSw debugging 

Enable DLSw UDP packet debugging 

(available with DLSw2.0) 

Disable DLSw UDP packet debugging 

(available with DLSw2.0) 

Enable SSP packet debugging for DLSw 

Disable SSP packet debugging for DLSw 

reset dlsw bridge-entry 

reset dlsw reachable-cache 

debugging dlsw { circuit 

[ correlator ] | tcp [ ip-address ] | 

reachable-cache } 

undo debugging dlsw { circuit 

[ correlator ] | tcp [ ip-address ] | 

reachable-cache } 

debugging dlsw udp 

undo debugging dlsw udp 

debugging dlsw packet [ receive 

[ip-address] | send [ip-address] ] 

undo debugging dlsw packet 

[ receive [ip-address] | send 

[ip-address] ] 

Enable LLC2 debugging debugging llc2 circuit [ correlator ] 

Disable LLC2 debugging 

Enable U frame debugging for LLC2 

Disable U frame debugging for LLC2 

Enable SDLC debugging 

Disable SDLC debugging 

Enable debugging for DLSw filtering 

undo debugging llc2 circuit 

[ correlator ] 

debugging llc2 packet 

undo debugging llc2 packet 

debugging sdlc { all | event | 

packet } 

undo debugging sdlc { all | event | 

packet } 

debugging dlsw filter 

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Operation 

Disable debugging for DLSw filtering 

Reestablish or delete the TCP connection 

to the remote peer 


Command 

undo debugging dlsw filter 

reset dlsw tcp [ ip-address ] 

5.4 DLSw Typical Configuration Examples 

5.4.1 DLSw Configuration of LAN-LAN 


This is a LAN-LAN style. Two LANs running the SNA are linked together through IP 

across WAN. 


10.120.25.1 

10.120.5.2 

RouterA 

WAN(IP) 

RouterB 

Ethernet0/0/0 

Ethernet0/0/0 

Ethernet 

LLC2 

LLC2 

Ethernet 

IBM AS/400 

PC(SNA) 

Figure 5-3 Network diagram for the DLSw configuration of LAN-LAN. 



[H3C] bridge enable 

[H3C] bridge 5 enable 

[H3C] dlsw local 10.120.25.1 

[H3C] dlsw remote 10.120.5.2 

[H3C] dlsw bridge-set 5 


[H3C-Ethernet0/0/0] bridge-set 5 




[H3C] dlsw local 10.120.5.2 



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In this way, two LANs across WAN can be connected. Note the IP related command is 

not shown here. On configuring the DLSw, the IP addresses between the configured 

local and the remote should be ensured to ip reachable (ping through), the same with 

the cases below. 

5.4.2 DLSw Configuration of SDLC-SDLC 


This is a SDLC-SDLC style. Two SDLCs are connected across WAN. 


110.87.33.11 

202.39.28.33 

RouterA 

Serial0/0/0 

WAN(IP) 

Serial1/1/1 

RouterB 

SDLC 

SDLC 

IBM AS/400 

PC(SNA) 

SDLC address:0xC1 

Figure 5-4 Network diagram for the DLSw configuration of SDLC-SDLC 

III. Configuration procodure 




[H3C] dlsw local 110.87.33.11 

[H3C] dlsw remote 202.39.28.33 



[H3C-Serial0/0/0] link-protocol sdlc 

[H3C-Serial0/0/0] baudrate 9600 

[H3C-Serial0/0/0] code nrzi 

[H3C-Serial0/0/0] sdlc status secondary 

[H3C-Serial0/0/0] sdlc mac-map local 0000-1111-0000 

[H3C-Serial0/0/0] sdlc controller c1 

[H3C-Serial0/0/0] sdlc mac-map remote 0000-2222-00c1 c1 

[H3C-Serial0/0/0] bridge-set 1 


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[H3C] dlsw local 202.39.28.33 

[H3C] dlsw remote 110.87.33.11 





[H3C-Serial1/1/1] code nrzi 

[H3C-Serial1/1/1] sdlc status primary 



[H3C-Serial1/1/1] sdlc mac-map remote 0000-1111-00c1 c1 


In this way, the SDLCs across WANs are connected. 

5.4.3 Configuring DLSw for SDLC-LAN Remote Media Transformation 


The following is a typical example of SDLC-LAN DLSw configuration, with SDLC 

multi-point supporting. In the example, the connected nodes c1 and c2 are PU2.0 typed 

nodes (ATM) and the c3 is PU2.1 typed node. The port connected with the multiplexer 

adopts the NRZ coding, and that connected with the PC3 adopts NRZI coding. 


RouterA 

110.87.33.11 

Ethernet0/0/0 

WAN(IP) 

202.39.28.33 

Serial0/0/1 

RouterB 

Serial0/0/0 

Ethernet 

SDLC 

Multiplexer 

SDLC 

IBM AS/400 

00-28-33-00-2a-f5 

PC1(SNA) 


PC2(SNA) 


PC3(SNA) 


Figure 5-5 Network diagram for SDLC-LAN configuration 





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[H3C] dlsw local 110.87.33.11 

[H3C] dlsw remote 202.39.28.33 







[H3C] dlsw local 202.39.28.33 

[H3C] dlsw remote 110.87.33.11 





[H3C-Serial0/0/0] sdlc status primary 



[H3C-Serial0/0/0] sdlc xid c1 03e00001 

[H3C-Serial0/0/0] sdlc mac-map remote 0014-cc00-54af c1 


[H3C-Serial0/0/0] sdlc xid c2 03e00002 

[H3C-Serial0/0/0] sdlc mac-map remote 0014-cc00-54af c2 


[H3C-Serial0/0/0] interface serial 0/0/1 

[H3C-Serial 0/0/1] link-protocol sdlc 

[H3C-Serial 0/0/1] baudrate 9600 

[H3C-Serial 0/0/1] code nrzi 

[H3C-Serial 0/0/1] sdlc status primary 

[H3C-Serial 0/0/1] sdlc mac-map local 0000-2222-0000 

[H3C-Serial 0/0/1] sdlc controller c3 

[H3C-Serial 0/0/1] sdlc mac-map remote 0014-cc00-54af c3 

[H3C-Serial 0/0/1] bridge-set 1 

[H3C-Serial 0/0/1] quit 

# If the local and remote networks are stable, you may configure the following 

commands to shorten the probing process. 

[H3C] dlsw reachable mac-exclusivity 

[H3C] dlsw reachable-cache 0014-cc00-54af remote 110.87.33.11 

It should be noted that on configuring router B, the MAC address in the sdlc mac-map 

remote and dlsw reachable-cache commands is he MAC address of the AS/400 

network card. But the MAC address should be configured in a inverse order, as the byte 

order of the Ethernet is inverse to that of the Token-Ring. If the peer end is Token-Ring, 

it needs not to be configured inversely. Neither need the virtual MAC address be 

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configured in the host side of the tunnel. The c1 and c2 in the above example are PU2.0 

typed devices, and the C3 is of PU2.1 type. 

5.4.4 Configuring VLAN-supported DLSw 


As shown in the following network diagram, ports Ethernet 0/0/0 and Ethernet 1/0/0 on 

switch LSW are connected to an IBM host and Router A respectively. Eth0/0/0 is 

assigned to VLAN 1, and Ethernet 1/0/0 is set to trunk mode and allows VLAN 1 on 

Ethernet 0/0/0 to pass. 

A subinterface is configured on Router A. This subinterface is assigned to VLAN1, 

allowing the IBM host to communicate with Router A. 

The use of VLAN improves security by preventing the packets between the IBM host 

and Router A from broadcasting by LSW. 


Figure 5-6 Network diagram for VLAN-supported DLSw 





[H3C] dlsw enable 

[H3C] dlsw local 1.1.1.1 


[H3C] dlsw bridge 1 

[H3C] interface ethernet 0/0/1.1 

[H3C-Ethernet0/0/1.1] vlan dot1q vid 1 

[H3C-Ethernet0/0/1.1] bridge 1 

[H3C-Ethernet0/0/1.1] interface ethernet 0/0/0 

[H3C-Ethernet0/0/0] ip address 1.1.1.1 255.255.0.0 


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[H3C] ip route-static 2.2.2.2 16 ethernet 0/0/0 




[H3C ]dlsw enable 



[H3C] dlsw bridge 1 


[H3C-Ethernet0/0/1] bridge 1 

[H3C-Ethernet0/0/1] ip address 2.2.2.2 255.255.0.0 


[H3C] ip route-static 1.1.1.1 16 ethernet 0/0/0 

3) Configure LSW 

# Create VLAN1, enter its view, and assign Eth0/0/0 to it. 

[H3C] vlan 1 

[H3C-vlan1] port ethernet0/0/0 

[H3C-vlan1] quit 

# Set Eth1/0/0 to trunk mode and allows VLAN1 to pass. 


[H3C-Ethernet1/0/0] port link-type trunk 

[H3C-Ethernet1/0/0] port trunk permit vlan 1 

5.4.5 DLSw2.0 Configuration Example 


Figure 5-7 presents a network where the following devices are deployed: 

• Router A, a DLSw2.0-enabled router. 

• Router B and Router C, DLSw-enabled (v1 or v2) routers. 

• A Cisco DLSw+ router. 

For all these routers, the multicast address is 224.0.10.0. 

It is required that the IBM host can communicate with all PCs. 

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Eth 0/0/0 

Eth 0/01: 

192.168.100.1 

WAN (IP) 

Router B 

PC 1 (SNA) 

Router A 

Multicast address: 

224.0.10.0 

Router C 

PC 2 (SNA) 

IBM AS/400 

CISCO 

PC 3 (SNA) 

Figure 5-7 Network diagram for DLSw2.0 configuration 


1) Configure RouterA 

system-view 

# Configure bridge-set 1. 



# Add the Ethernet 0/0/0 interface to bridge-set 1. 

[H3C] interface Ethernet 0/0/0 



# Enable multicast globally. 

[H3C] multicast routing-enable 

# Configure the IP address of the Ethernet 0/0/1 interface, and enable IGMP and 

PIM-DM on the interface. 

[H3C] interface Ethernet 0/0/1 

[H3C-Ethernet0/0/1] ip address 192.168.100.1 24 

[H3C-Ethernet0/0/1] igmp enable 

[H3C-Ethernet0/0/1] igmp host-join 224.0.10.0 

[H3C-Ethernet0/0/1] pim dm 


# Configure local/remote DLSw peers, enable DLSw multicast, set the maximum 

number of attempts to send an explorer frame and specify the local bridge set. 

[H3C] dlsw local 192.168.100.1 

[H3C] dlsw multicast 

[H3C] dlsw max-transmission 3 

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[H3C] dlsw remote 192.168.100.2 version 2 

When configuring Router B and Router C, you need first make sure the DLSw version 

that they support. If DLSw2.0 is supported, configure them with reference to Router A. 

If DLSw1.0 is supported, omit the settings of multicast and explorer frame 

retransmission. 

For the configuration on the CISCO router, refer to the associated Cisco documents. 

5.5 Troubleshooting DLSw 

The normal communication of the DLSw needs sound cooperation of the involved two 

SNA devices and the two routers running the DLSw. Any fault in the cooperation 

between two nodes may cause connection failure. 

Fault one: The TCP connection cannot be created and the displayed status of the 

display dlsw remote is DISCONNECT. 

To create the TCP connection is the first step for successful DLSw connection. Failure 

in creating the TCP connection is the problem between two routers, generally due to 

wrong IP route configuration. The IP address of the remote can be checked to be 

reachable or not by the ping command with the source address. And the display ip 

routing-table command can also be used to examine whether there is route arriving at 

the network segment. After both sides establishing correct route, the TCP connection 

can be then created. 

Fault two: The circuit cannot be correctly created and the virtual circuit cannot attain to 

CONNECTED status when the display dlsw circuit command is performed. 

Many reasons can cause failure in creating the circuit. First of all, the TCP connection 

of the peer end should be ensured to be created successfully. After this requirement is 

satisfied, the circuit creation failure usually lies in the wrong cooperation between the 

router and the SNA device, mainly the wrong SDLC configuration. 

First enable the SDLC debugging, and check whether the SDLC interface can 

receive/forward packets normally by performing the display interface command. If it 

cannot receive/forward packets correctly, it is generally because of the faults in the 

coding scheme, baud rate or clock configuration on the interface, which can be solved 

by revising the interface configuration parameters of the router or adjusting the 

configuration parameters of the SDLC device. 

If packets are received and forwarded correctly, examine whether the configuration of 

the PU type is correct. Use the sdlc xid command to configure the XID and change the 

configuration of the PU type. 

If the packets are received and forwarded correctly, use the display dlsw circuit 

verbose command to check whether the virtual circuit can enter the CIRCUIT_EST 

status. If it cannot all the time, it indicates that something is wrong with the cooperation 

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between the configured virtual MAC address and the remote. This problem can usually 

be tackled by revising such configuration parameters as sdlc mac-map remote, etc. 

If the circuit can reach the CIRCUIT_EST status, but cannot reach the CONNECTED 

status, it indicates that the configuration of the SDLC on the router does not match that 

of the SNA devices. Examine the configuration of the SDLC devices on both sides and 

the configuration of the router, for example, check if the XID of the SNA device is 

properly configured (PU2.1), and if the XID of the router is properly configured (PU2.0). 

If there is nothing wrong with the configuration, check if the SDLC line on the SDLC 

main device side (such as the AS/400 or S390) is activated. Sometimes the SDLC line 

needs to be activated by hand to perform communication. 

5.6 Tips for DLSw 2.0 Configuration 

• For a DLSw2.0-supported router, DLSw is enabled by default with multicast 

disabled upon startup of the router. To allow the router to receive multicast packets, 

you need to execute the dlsw multicast command to enable DLSw multicast first. 

• To create a local peer successfully, you must make sure that the IP address of the 

local peer is the IP address of an interface on the router. 

• After a router reboot, the local peer cannot be created if you have changed the IP 

address of the interface associated with the local peer before the reboot. As a 

result, the DLSw configuration you have made will be lost and you need to make 

new DLSw configuration. 

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Chapter 6 DLSw Redundancy Configuration 


6.1 DLSw Redundancy Overview 

As the DLSw forwarding mechanism in an Ethernet environment is based on 

transparent bridging, DLSw has no way to detect the nodes along the forwarding path 

that a frame has traveled. In Ethernet environments with two or more DLSw routers for 

redundancy, this can cause problems such as reachability confusion, explorer looping 

and flapping, and incorrect circuit disconnection by an Ethernet switch. 

DLSw redundancy, an enhancement to the basic DLSw functions for routers, resolves 

those problems. In addition, it allows multi-system redundancy and load sharing. 

The following describes the fundamentals of DLSw redundancy in Ethernet 

environments: 

I. Election of the master router 

To prevent two or more DLSw routers on the same Ethernet from establishing multiple 

circuits for a single SNA session, you must centralize the management of circuit 

establishing processes for all the DLSw routers on the Ethernet. Therefore, it is 

required to elect a master router for centralized management. 

1) After you enable DLSw redundancy on an Ethernet interface of a router, the router 

sends a multicast frame to the specified multicast address every 10 seconds 

through the interface, which contains the priority of the router and the MAC 

address of the interface. 

2) After receiving a multicast frame, a router compares the priority carried in the 

frame with its own priority. If its priority is higher (the smaller the priority value, the 

higher the priority), it is elected as the master DLSw router (hereinafter referred to 

as the master). If the two routers have the same priority, the router with the smaller 

MAC address is elected as the master. 

After election, the master continues sending multicast frames, and at the same time 

establishes LLC2 connections to all slave DLSw routers (hereinafter referred to as the 

slaves). Each slave sends the MAC address of its interface to the master, and the 

master advertises the MAC addresses of the interfaces on all slaves in the backup 

group. 

When the master fails, the election process is initiated to elect a new master. 

II. Forwarding of an explorer (translation of the source MAC address in an 

explorer) 

The DLSw router uses explorers to check whether a destination MAC address is 

reachable on an Ethernet. However, when two or more routers are present on the 

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Ethernet, the explorers are forwarded among the routers in a DLSw backup group, 

resulting in incorrect reachability information. To solve the problem, the DLSw 

redundancy feature translates the source MAC addresses of the explorers into the 

MAC address of the interface on the router. 

1) When sending an LLC2 explorer to the local Ethernet, the router translates the 

source MAC address of the frame into the MAC address of its interface. 

2) When receiving an explorer from the local Ethernet interface, the router checks 

whether the destination MAC address of the frame is the MAC address of an 

interface on another router in the backup group. If so, the router simply discards 

the explorer; otherwise, the router updates its reachability information table and 

continues to send explorers as needed. 

III. Distribution of circiuts 

The circuit here refers to the connection between an IBM host and an SNA terminal. 

After completing the exploring, the master and slaves start to carry circuits established 

between the IBM host and the SNA terminals. The master maintains a circuit database 

for all routers including the slaves, and distributes circuits according to the current loads 

of the routers, preventing two or more DLSw routers on the same Ethernet from 

establishing multiple circuits for a single SNA session. At the same time, the master 

looks up the recorded number of circuits established on each router and selects the 

router with the least established circuits for new circuits, ensuring that the numbers of 

circuits established on the routers are approximately equal. If a circuit on a slave is 

disconnected, the master updates the recorded circuit information about the slave. 

IV. Forwarding of data frames in an environment with Ethernet switches 

When DLSw redundancy is applied to an environment with Ethernet switches, multiple 

ports of an Ethernet switch may receive frames with the same source MAC address 

from different DLSw routers simultaneously. In this case, the switch concludes that 

these ports have received the same frame from the same host. As a result, the 

spanning tree protocol (STP) blocks all the ports but one for forwarding the frames, 

disconnecting the circuits incorrectly. DLSw redundancy solves the above problem by 

replacing MAC addresses as follows: 

• When receiving a frame from the WAN, the router replaces the source MAC 

address of the frame (that is, the MAC address of the remote SNA device) with its 

local virtual MAC address, and then forwards the frame to the LAN. 

• When receiving a frame from the Ethernet, the router replaces the destination 

MAC address with the MAC address of the remote SNA device, and then forwards 

the frame to the WAN. 

After a router is elected as the master, each slave sends its MAC address translation 

entries to the master. When a slave fails, the master takes over the translation 

responsibility until the slave comes back up. 

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6.2 Configuring DLSw Redundancy 

The following section describes the redundancy configuration tasks: 

• Enabling DLSw Redundancy 

• Enabling the Ethernet Switch Support Feature 

• Configuring the DLSw Redundancy Timer (Optional) 

Before enabling the DLSw redundancy function, you must enable the DLSw function 

and make sure that the TCP channels have been established successfully, that is, the 

local and remote DLSw peers are created successfully. 

6.2.1 Enabling DLSw Redundancy 


Table 6-1 Enable DLSw redundancy 

Operation 

Enable DLSw redundancy 

Disable DLSw redundancy 

Command 

dlsw ethernet-backup enable 

multicast-mac-address [ priority value ] 

undo dlsw ethernet-backup enable 

The smaller the priority value, the higher the priority. For routers with the same priority, 

a router with a smaller MAC address has a higher priority. 

Note: 

You can configure a bridge set on an Ethernet interface so that the interface can 

receive frames. But this is not compatible with DLSw redundancy. Therefore, never do 

so if you want to enable DLSw redundancy. 

6.2.2 Enabling the Ethernet Switch Support Feature 

In actual applications, if DLSw redundancy routers are directly or indirectly connected 

to Ethernet switches, enable the Ethernet switch support feature. That is, configure the 

map entries between the local virtual MAC addresses and the MAC addresses of the 

remote SNA devices. 


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Comware V3 


Table 6-2 Enable the Ethernet switch support feature 

Operation 

Configure the map entry between a local 

virtual MAC address and the MAC 

address of a remote SNA device 

Remove the map entry between a local 

virtual MAC address and the MAC 

address of a remote SNA device 

Command 

dlsw ethernet-backup map local-mac 

local-mac-address remote-mac 

remote-mac-address [ neighbour 

neighbour-mac-address ] 

undo dlsw ethernet-backup map 

local-mac local-mac-address 

remote-mac remote-mac-address 

After you specify the neighbour-mac-address argument, the specified router will keep a 

backup of the map entries. All these MAC addresses must be in the format of 

xxxx-xxxx-xxxx and in token ring order. 

You are recommended to use the dlsw reverse command in system view to 

automatically translate MAC addresses. 

6.2.3 Configuring the DLSw Redundancy Timer 


Table 6-3 Configure the DLSw redundancy timer 

Operation 

Configure the DLSw redundancy timer 

Restore the default value of the DLSw 

redundancy timer 

Command 

dlsw ethernet-backup timer value 

undo dlsw ethernet-backup timer 

This timer indicates the time for which the master in DLSw redundancy waits before 

sending a positive or negative response upon receipt of a circuit establishing request. It 

defaults to 500 ms. 

6.2.4 Displaying and Debugging DLSw Redundancy 

Execute the display command in any view, the debugging command in user view, and 

the dlsw reverse command in system view. 

Table 6-4 Display and debug DLSw redundancy 

Operation 

Display all the neighbors of the current 

router 

Display address translation information 

on a router with the Ethernet switch 

support feature configured 

Command 

display dlsw ethernet-backup 

neighbour 

display dlsw ethernet-backup map 

6-4


Comware V3 

Operation 

Display circuit backup information on a 

router with DLSw redundancy enabled 

Display the reachability information of 

circuits on a router with DLSw 

redundancy enabled 

Enable debugging for DLSw redundancy 

Disable debugging for DLSw 

redundancy 

Enable DLSw reachability debugging 

Disable DLSw reachability debugging 

Clear the records about all circuits that 

the router and its neighbors have 

established since DLSw redundancy is 

enabled 

Clear the MAC address map of the 

Ethernet switch support feature 

Convert a MAC address (token ring 

order to/from Ethernet order) 


Command 

display dlsw ethernet-backup circuit 

display dlsw reachable-cache 

debugging dlsw ethernet-backup 

undo debugging dlsw 

ethernet-backup 

debugging dlsw reachable-cache 

[ local | remote ] 

undo debugging dlsw 

reachable-cache 

reset dlsw ethernet-backup circuit 

reset dlsw ethernet-backup map 

dlsw reverse mac-address 

6.2.5 Configuration Example of DLSw Redundancy Without Switch Support 


DLSw routers work in LAN-LAN model and IP is run across WANs. Multiple redundant 

DLSw routers are connected to an Ethernet through a hub. It is required to reasonably 

distribute circuits between the two terminals and the AS/400 device by implementing 

the master election and circuit distribution policy. 

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Eth0/0/0 

Eth0/0/1 

Router A 

Eth0/0/0:5.5.5.1 

WAN (IP) 

5.5.5.2 

Eth0/0/0 

6.6.6.2 

Router B 

Router C 

Eth0/0/1 

Ethernet 

LLC2 

Eth0/0/0 

7.7.7.2 

Router D 

Eth0/0/1 

LLC2 

Hub 

PC (SNA) 

PC (SNA) 

IBM AS/400 

Figure 6-1 DLSw redundancy configuration without switch support 









[H3C-Ethernet0/0/0] dlsw ethernet-backup enable 9999-9999-9999 






[H3C-Ethernet0/0/0] dlsw ethernet-backup enable 9999-9999-9999 priority 1 

3) Configure Router C 




[H3C] ip router-static 5.5.5.0 24 ethernet0/0/0 



4) Configure Router D 





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Note that as the IP address assigned to interface Eth0/0/0 on Router A is 5.5.5.1, routes 

to Router A must be configured on Router C and Router D to allow them to set up TCP 

connections with Router A. 

6.2.6 Configuration Example of DLSw Redundancy With Switch Support 


DLSw routers work in LAN-LAN model and IP is run across WANs. Two DLSw routers 

are connected to two SNA terminals through an Ethernet switch. DLSw redundancy 

with the Ethernet switch support feature ensures that circuits can be set up successfully 

between the AS/400 device and the two terminals. 


Eth0/0/0:5.5.5.1 

Router A 

Ethernet 

LLC2 

Eth0/0/0 

Eth0/0/1 

5.5.5.2 

Router B 

0007-3fe0-8ce7 (in token ring order) 

Eth0/0/0 

Eth0/0/1 

WAN (IP) 

6.6.6.2 

Router C 

00e0-3f34-e95a (in token ring order) 

LLC2 

LAN switch 

LLC2 

IBM AS/400 

0004-acde-07a6 (in token ring order) 

PC (SNA) 

PC (SNA) 

Figure 6-2 DLSw redundancy configuration with an Ethernet switch 














[H3C-Ethernet0/0/0] dlsw ethernet-backup enable 9999-9999-9999 priority 1 

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Comware V3 


[H3C-Ethernet0/0/0] dlsw ethernet-backup map local-mac 1111-1111-1111 

remote-mac 0004-acde-07a6 neighbour 0007-3f34-e95a 

3) Configure Router C 







[H3C-Ethernet0/0/0] dlsw ethernet-backup map local-mac 2222-2222-2222 

remote-mac 0004-acde-07a6 neighbour 0007-3fe0-8ce7 

Note that: 

• All the MAC addresses in the dlsw ethernet-backup map command must be in 

token ring order. 

• 0007-3fe0-8ce7 (token ring order) corresponds to 00e0-fc07-31e7 (Ethernet 

order). The reversal is carried out as follows: 

07 = 00000111 The bit swap value of this byte is 11100000 = e0 

3f = 00111111 

The bit swap value of this byte is 11111100 = fc 

e0 = 11100000 The bit swap value of this byte is 00000111 = 07 

8c = 10001100 The bit swap value of this byte is 00110001 = 31 

e7 = 11100111 

The bit swap value of this byte is 11100111 = e7 

Likewise, 0007-3f34-e95a (token ring order) corresponds to 00e0-fc2c-975a (Ethernet 

order). You are recommended to use the dlsw reverse command in system view to 

automatically translate MAC addresses. 

• Each SNA terminal is required to translate the destination MAC address of a 

transmitted frame into the local MAC address configured using the dlsw 

ethernet-backup map command. As the terminals are required to use different 

destination MAC addresses, multiple dlsw ethernet-backup map commands 

must be configured on the DLSw router to obtain multiple local MAC addresses. 

6.2.7 Troubleshooting DLSw Redundancy 

Symptom 1: 

Unable to configure the dlsw ethernet-backup enable 9999-9999-9999 priority 1 

command in Ethernet interface view. 

Solution: 

Check whether the bridge-set command is configured on the interface: 

1) Execute the display this command in Ethernet interface view to view the 

configuration of the interface. 

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2) Remove the bridge set configuration from the interface by using the undo 

bridge-set command (if any). 

3) Make sure that the bridge set is removed and then configure DLSw redundancy. 

Symptom 2: 

After executing the dlsw ethernet-backup map local-mac xxxx-xxxx-xxxx 

remote-mac xxxx-xxxx-xxxx neighbour xxxx-xxxx-xxx command in Ethernet interface 

view, you use the dlsw ethernet-backup map command. However, the neighbor fails 

to back up the map entries, or the circuits cannot be established between the SNA 

devices. 

Solution: 

1) Check whether the MAC addresses in the dlsw ethernet-backup map local-mac 

xxxx-xxxx-xxxx remote-mac xxxx-xxxx-xxxx neighbour xxxx-xxxx-xxxx 

command are in token ring order. 

2) Check whether the destination MAC address configured on the SNA terminal is 

the local MAC address configured in the command. 

6-9

2.2 OSI Data Link Layer Configuration

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