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ULP-based VLANs are a comparatively new and useful class of VLAN. Depending on VLAN implementation, VLAN membership can be based on IP, IPX, AppleTalk, and other popular LAN protocols. However, Layer 3-based VLANs operate at a slower processing rate. Examining each packet well into the datagram portion of the packet is time consuming in comparison to looking at a MAC address. Multicast VLANs consume even more switch resources than basic Layer 3 switch VLAN variations. This is because the switch not only needs to examine the Layer 3 portion of the packet, it also needs to maintain membership lists of the hosts involved in the multicast groups, along with maintaining distinct VLANs for each multicast group. VLAN Configuration and Implementation Regardless of the VLAN membership methodology, VLAN implementations represent an additional level of network complexity beyond the traditional plug-and-play "one network, one wire" approach. When VLANs first appeared, they were limited to a standalone switch, which meant that VLANs in large networks were really only useful for creating broadcast domain port groups, which could be connected to another switch or router that was part of the same Layer 3 network. Figure 6.13 provides a simple example.
Figure 6.13. Switches running independent VLANs connected with interconnection links. When MAC and Layer 3-based VLANs became available, however, a means to distribute VLAN information between switches became necessary. Cabletron Systems' SecureFast and Cisco Systems' InterSwitch Link (ISL) were both very popular, but proprietary, and hence incompatible distributed VLAN solutions. Therefore, it was possible to deploy enterprise VLANs, provided you used switches that were all from the same switch vendor. The major source of incompatibility with SecureFast and ISL (and other proprietary VLAN distribution schemes) was the method they used to establish and describe VLAN membership, which was accomplished through the use of some form of packet (or frame) tagging. There are two forms of packet tagging: implicit and explicit. Implicit packet tagging uses an existing packet attribute to associate a packet
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Understanding the Network A Practic
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IOS Authentication and Accounting S
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About the Reviewers These reviewers
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Tell Us What You Think As the reade
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mostly dealt with interconnecting m
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• A short introduction to SNMP Ap
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In theory, a computer network can o
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Coaxial cable has a single solid co
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• Radio transmission—It is achi
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• Baseband transmission applies t
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Ring Topology Figure 1.3. The bus t
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Packets and frames are often used a
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Asynchronous transmission involves
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Figure 1.6. Collision handling unde
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In a ring topology, a token is pass
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Repeaters The repeater was introduc
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the network. If your 50-node networ
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Figure 1.12. A collection of nodes
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their destination, type, and conten
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shop, you are using Novell's Direct
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Figure 1.14. The OSI and Internet r
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Layer 7: Application This layer pro
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end-to-end, sequenced data delivery
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outer, the delivery path might be d
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and network transport is a very imp
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Figure 1.16. The "bottom up" commun
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Chapter 2. The Networker's Guide to
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Internet Society, a nonprofit organ
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• First, it performs translations
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Figure 2.2. The IP header. • Vers
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To assist in the reassembly process
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Figure 2.3. IP address classes comp
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taking the natural mask of the addr
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Classful Subnetting Examples The im
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21 2,000 8,000 255.255.248.0 22 1,0
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classful-based address space model.
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Table 2.6. Classless Network Addres
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NOTE Because CIDR is used for addre
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will connect in the future, it is b
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Routers are also called intermediat
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IP datagrams for which the local ho
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1. The Layer 3 to Layer 2 address m
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3. Router B—Router B receives the
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connected networks. Figure 2.11 ill
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Figure 2.12. A simple regional (ISP
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gw1, gw2, gw4 3 gw1, gw3, gw4 3 gw1
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Dynamic routing might not be requir
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The transport layer as a whole repr
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window to reflect changes in the pa
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The TCP Header The TCP header provi
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53 DNS (Domain Name Service) 67 BOO
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SNMP Simple Network Management Prot
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uses both TCP and UDP for service d
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RFC 974 Mail routing and the domain
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Figure 3.1. Physical versus logical
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Figure 3.2. The AppleTalk protocol
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AppleTalk Address Resolution Protoc
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of 400 microseconds, in addition to
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Along with the SAP, there is a 5-by
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delivery is a best-effort delivery
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• DDP checksum (long header only)
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eachable within the internetwork. T
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information from the router's other
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AppleTalk Update Based Routing Prot
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• type is the service classificat
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application layers. AppleTalk has n
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Figure 3.10. ZIP message formats. E
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Printer Access Protocol Printer Acc
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Figure 3.11. Novell (IPX) protocol
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The other nodes on the network that
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Figure 3.13. IPX datagram format.
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the cumulative information gleaned
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• Hop Count is the number of rout
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Upper Layer Protocols IPX is used t
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Msg.Add.Name Adds a unique name to
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Related RFCs RFC 1001 RFC 1002 RFC
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service enhancement or replacement
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Figure 4.1. The LLC interfaces in r
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it does not provide for error recov
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and smooth pattern flow enables MTL
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cabling, backbone length 800m Categ
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combination of light refraction and
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NOTE Cladding is the glass "shell"
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Ethernet The original Ethernet prot
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UTP telephone cabling infrastructur
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Since the introduction of the IEEE
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In the event that two Ethernet end-
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The 802.3 frame type used in Figure
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• Frame check sequence (4 bytes)
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• Physical layer signaling (PLS)
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cable segment length (for coaxial s
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transmission medium using BNC (Brit
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Figure 4.12. A basic 3-cable 10Base
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Figure 4.14. 10Base-T hub-to-hub in
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Figure 4.16. 10Base-T in a consulta
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• Support for full-duplex operati
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mechanisms, in terms of encoding an
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etween different PHY encoding imple
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100Base Ethernet) is based on the p
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The Gigabit PHY The Gigabit PHY con
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CSMA/CD is sensitive to operating r
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The main advantage of using FDR ove
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have to transmit against the priori
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• Ring timing maintenance—The A
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check the lobe cable. If the lobe t
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Token Ring addresses are expressed
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• Report Active Monitor Error (RA
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they first join the ring or in the
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Figure 4.22. The IBM type 1 MIC con
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FDDI Work on the Fiber Distributed
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However, all this comes at a cost,
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Figure 4.25. FDDI MAC data frame an
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topologies needed for the transmiss
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Chapter 5. WAN Internetworking Tech
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Placing a Call The functional model
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LATAs to provide local exchange ser
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The PSTN was originally designed fo
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sampling rate is 8,000 times per se
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Figure 5.1. A multiplexer from a lo
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Table 5.1. The American (DS) and In
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The M24/D4 frame standard is the ba
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contains consecutive ones and zeros
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• Line loopback/line build-out (L
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process. The T3 multiplexer adds st
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committee. The committee provided t
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The photonic layer defines the elec
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such as T1/E1, FDDI, and others. Th
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SS7 signaling components are connec
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SCCP operates as an OSI-RM Layer 3.
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WAN point-to-point links. It can be
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Figure 5.11. The ISDN protocol refe
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• The R interface acts as a point
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• Flag—This is an 8-bit (011111
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terminals attached to the ISDN swit
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X.25 networks are comprised of four
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Frame Relay, like the ISDN effort i
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• Flag—This functions as a fram
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Figure 5.17. the B-ISDN reference m
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environments is implemented using A
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endpoints. A Virtual Path Link (VPL
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ATM endpoints. The user adaptation
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Page 289 and 290: PPP PPP can provide multiprotocol d
Page 291 and 292: PPP Framing There are three HDLC fr
Page 293 and 294: • The HDLC and PPP data-link prot
Page 295 and 296: Chapter 6. Network Switches In this
Page 297 and 298: Figure 6.1. Partial and full mesh m
Page 299 and 300: protocol. Figure 6.3 illustrates th
Page 301 and 302: All hosts can see the traffic that
Page 303 and 304: To get a better understanding of th
Page 305 and 306: Figure 6.5. A bridged LAN with span
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Page 313 and 314: The Impact of Switching on Traditio
Page 315 and 316: • Switch backplane—Also referre
Page 317 and 318: Switch Port Flow Control In full-du
Page 319 and 320: In the event that the primary trunk
Page 321 and 322: Figure 6.9. Layer 2 collision domai
Page 323 and 324: Figure 6.10. Multiport repeaters an
Page 325 and 326: Figure 6.11. Distributed and collap
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Page 329 and 330: Ideally, the goal of all switch and
Page 331 and 332: Cut-through uses the same technolog
Page 333 and 334: VLANs A switch that supports VLAN p
Page 335: MAC Address-Based VLANs Another com
Page 339 and 340: The configuration layer uses the Ge
Page 341 and 342: Layer 2 infrastructures to operate
Page 343 and 344: need. This method not only allocate
Page 345 and 346: transmitting and receiving. Without
Page 347 and 348: ATM-specific applications would be
Page 349 and 350: ATM private-class switches are comp
Page 351 and 352: Because both the VPI and VCI are us
Page 353 and 354: environment. The goal is to have La
Page 355 and 356: Broadcast and Unknown Server The Br
Page 357 and 358: Figure 6.15. An LEC and its VCC rel
Page 359 and 360: ATM hosts are accomplished by estab
Page 361 and 362: • VLANs • Full-duplex switch po
Page 363 and 364: Chapter 7. Introduction to Cisco Ro
Page 365 and 366: The 4000 series routers come in a t
Page 367 and 368: series routers, this partition can
Page 369 and 370: need to crimp the CAT 5 strands fol
Page 371 and 372: Use the cable set to build the cabl
Page 373 and 374: Step 2. This command specifies whic
Page 375 and 376: AppleTalk FDDI IPX Token Ring VINES
Page 377 and 378: The IOS Command Line and Configurat
Page 379 and 380: disconnect Disconnect an existing n
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Page 383 and 384: • Router(config)#hostname test-ro
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Null Null interface Tunnel Tunnel i
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Router(config)#ip rou? route routin
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Ctrl+P, up arrow Previous command i
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mop Copy from a MOP server (not ava
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Now let's see what is on the PCMCIA
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When copying any file, unless no pr
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Ethernet LANs with a dedicated T1 c
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Compiled Fri 03-Apr-98 07:00 by rna
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172.16.2.0 /25 172.16.2.128 /26 or
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Ridge-GW(config)# ip route 0.0.0.0
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In addition to their native protoco
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D - EIGRP, EX - EIGRP external, O -
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Configuring Dumb Terminal Service T
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Ctrl+Shift+6+X suspends a session).
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cornpops|Printer on Cisco termserve
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Concord-GW(config-if)#flowcontrol h
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The AUX port configuration for Ridg
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outer and enter the break sequence
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Setting the conf-reg Value in ROM M
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• Register setting 0x2010—Confi
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8. 9. Router#configure terminal 10.
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!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
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Router#config t Enter configuration
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-#- ED --type----crc--- -seek--nlen
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to xmodem or TFTP (2600 only) an IO
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Mountain Standard Time (MST) -7 Pac
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eference time is BB0FC7AA.95E93186
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in production for a little while. T
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use debug mode often. When using th
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uucp UNIX-to-UNIX copy system IOS a
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Log Management Logs are useless unl
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IOS Authentication and Accounting I
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hostnames (which can be corrected w
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$telnet 192.160.56.5 Trying 192.160
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In this example, the authentication
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makes it easier to configure, becau
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define what authentication type sho
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Caution should be taken when using
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pairs (similar to those used to cre
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• Using rommon and disaster recov
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In the following section, we review
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Deciding to Use a Routing Protocol
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Now, here is the qualifier: Not eve
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If RIP was the routing protocol for
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Distance Vector Protocols All routi
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space) based on a power of 2. Class
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address space), but you would run i
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destination address that falls with
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the different IP address spaces int
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Weaknesses of Static Routing Static
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Today, RIP is considered by some to
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RIP 192.124.32.0 /24 192.124.35.1 3
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All routers on the network keep tra
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RIP's Value Today RIP is old, it's
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• Better reliability—OSPF route
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Figure 8.10. Single- and multi-area
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• Internal routers—These router
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to the backbone. In Figure 8.13, al
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Figure 8.14. OSPF router designatio
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oundary routers. They describe netw
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outer's point of view. The path con
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Autonomous Systems and Exterior Rou
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Figure 8.16. The IGP to ERP handoff
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Figure 8.17. The BGP finite state m
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EGPs have been increasing in popula
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Chapter 9. Advanced Cisco Router Co
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specified ACL number range. Table 9
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default, all traffic is denied. Onl
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asbr-a2#config t Enter configuratio
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trying to build ACLs with the comma
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trace Multicast trace IGMP log Log
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Tftp Trivial File Transfer Protocol
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access-list 100 permit tcp any 172.
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Table 9.5. AppleTalk ACL Filtering
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Figure 9.1. The AnyCo corporate App
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One word of caution: If you plan to
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You can also log hits on ports by a
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Table 9.8. Route-Map Operators for
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exists, a group identifier (which c
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hegel# With this configuration, bec
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NAT is commonly used in a fashion s
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The [prefix-length] or [netmask] se
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NAT's Shortcomings Although NAT is
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NOTE Administrators beware: Tunneli
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connects, the active key informatio
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encapsulation, framing, and line si
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asbr-a2(config-if)#ip address 172.1
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problem if you are provisioning ISD
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22:41:34: %LINK-3-UPDOWN: Interface
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POP mail request is made. Now let's
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leibniz(config-if)#backup interface
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When the primary link fails, the BR
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1.544Mbps. The actual transport lin
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the cost-effective and bandwidth-ef
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interface configuration subcommand
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it is possible to exchange packets
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interface serial0.2 point-to-point
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Figure 9.6. A multipoint FR example
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2. ATM encapsulation must be enable
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are commonly used in large-scale cl
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persephone(config)#interface atm 3/
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• The creation and application of
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Chapter 10. Configuring IP Routing
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After you have a list of requiremen
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Control commands: Displaying
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not active, it is quite common for
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Incoming update filter list for all
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When changing any IP routing behavi
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asbr-a1(config-if)#^Z asbr-a1# When
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For asbr-a2 to reach all the testne
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192.168.160.0/30 is subnetted, 1 su
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order to maintain computability wit
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Configuring Dynamic IGP and EGP IP
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passive-interface s1 By enabling th
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asbr-a1(config-router)#network 12.0
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To verify that the adjusted route m
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The command is a general routing p
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EIGRP, as I'm sure you have guessed
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No matter how the announcement entr
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Incoming update filter list for all
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is adjustable using the router con
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• IOS also supports various debu
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outers: • Backbone Routers—Thes
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process. The router would construct
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e1/1 192.168.9.0 fe0/0 192.168.0.0
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An alternative to this is to use th
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C 192.168.191.0/24 is directly conn
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Link State Age Interval is 00:20:00
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C 192.168.191.0/24 is directly conn
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to asbr-a1 was a remote office that
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interface Serial1 ip address 192.16
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which to exchange OSPF messages. Th
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OSPF Monitoring Commands Throughout
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• • • NOTE • will display
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Figure 10.4. AURP tunnel interfaces
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appletalk glean-packets hostname as
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For many users, the usefulness of B
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internal/Internet access router whe
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externally destined traffic arrives
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Routers asbr-a1/a2 and asbr-b1/b2 a
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BGP Reflectors An alternative to ha
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network 192.168.0.0 mask 255.255.25
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dynamic routing protocols are used
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Figure 10.8. An example network run
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Controlling Redistribution In some
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hostname ABR-a57 ! access-list 1 pe
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access-list 2 deny 10.0.1.0 access-
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Keep in mind that route-maps, li
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Chapter 11. Network Troubleshooting
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However, the most valuable tool of
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• Description of primary function
Page 690 and 691:
of cable fault, different CSFSs are
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For Windows Systems, check out the
Page 694 and 695:
command. On a Windows NT system, us
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#Do not change these variables logf
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# If any of the hosts fail to respo
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upgrade. So, when the time comes to
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throughput over time, instead of si
Page 704 and 705:
protocol is the most prone to perfo
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NOTE When looking at network broadc
Page 708 and 709:
NOTE Another common network error n
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and the physical ring segment that
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tolerances the frames, timing shift
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practical terms, this means that at
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etransmissions, however, usually ha
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4. Don't get lost in the big pictur
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• Link and services monitoring, n
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eports on network utilization, avai
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o Bandwidth utilization rates o Rat
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and improved management capabilitie
Page 728 and 729:
After the supported SNMP version is
Page 730 and 731:
Table 11.3. ASN.1 Keywords Used wit
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application-wide tags, which are us
Page 734 and 735:
TestSequence ::= SEQUENCE { example
Page 736 and 737:
The MIB-2 and RMON-MIB modules are
Page 738 and 739:
iso.identfied-orgnaization.dod.inte
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accepted values are getRequest, get
Page 742 and 743:
Spectrum is available in both UNIX
Page 744 and 745:
Figure 11.8. Windows NT 4.0 SNMP Ag
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To access any of the NT SNMP agent
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The installation of the SNMP agent
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Figure 11.13. The Windows 95/98 Sel
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Figure 11.15. Locating the Windows
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Figure 11.17. The SNMP configuratio
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2. Scroll to Network Connectivity o
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sysLocation information, go to the
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example that just implements the ba
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protocol, service, and application
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RFC 1089 RFC 1147 RFC 1155 RFC 1157
Page 766:
Appendix A. Binary Conversion Table
show all

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