Dell Force10 Interoperability Guide

Dell Force10
Interoperability Guide
Interoperability Guide on Key Features
Dell │ Force10
Force10 Marketing Team
June 2012

Dell Networking
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June 2012
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Contents
Introduction .................................................................................................................................................................... 2
Purpose of This Document ......................................................................................................................................... 2
VTP .................................................................................................................................................................................... 3
Spanning Tree Protocols ............................................................................................................................................. 4
PVST (FTOS) and PVST+ (IOS) ............................................................................................................................. 5
Switch Configuration ........................................................................................................................................... 6
Convergence Test: ................................................................................................................................................ 7
Results: ..................................................................................................................................................................... 7
Results: ..................................................................................................................................................................... 7
RSTP and RPVST+ .................................................................................................................................................. 7
Switch Configuration ........................................................................................................................................... 8
Convergence Test: ............................................................................................................................................... 9
Results: .................................................................................................................................................................. 10
Results: .................................................................................................................................................................. 10
MSTP ...................................................................................................................................................................... 10
Implementation Note ............................................................................................................................................. 11
Miscellaneous ....................................................................................................................................................... 11
Port Channels ............................................................................................................................................................... 11
Figures
Figure 1 : VTP Basic Test Setup ............................................................................ 3
Figure 2: Port Channel FTOS Screenshot ............................................................... 4
Figure 3 : Dell Force 10 and Cisco Catalyst 6509 PVST+ Test Setup ............................... 5
Figure 4 : RSTP and PVST+ Setup......................................................................... 8
Figure 5 : S4810_1 Configuration ......................................................................... 8
Figure 6 : S4810_2 Configuration ........................................................................ 9
Figure 7 : Catalyst 6509 Configuration .................................................................. 9
Figure 8 : Port Channel Setup ............................................................................ 11
Figure 9 : Port Channel Configuration .................................................................. 12
Tables
Table 1 : Dell Force 10 vs. Cisco Features
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Introduction
Vendors influence network architectures through features and functionality found in the equipment
they manufacture, leading to the overall look and feel of the network. For example, some vendordriven
networks require a 3-tier model with core, distribution and access. Although this has been the
prevalent design in the past 10 years or so, the overall increase in capex and opex expenses due to the
number of switches at network layer has remained on par. Such design deserves another look.
The proprietary nature of the protocols and features locked customers to one particular vendor, with
some forced interdependencies of some features. Customers were forced to use proprietary features
by the vendor-created dependencies between protocols. For example, early Cisco IP phones rely on
CDP to collect network information and use a Cisco-proprietary PoE standard, not the IEEE standard.
The Dell Force10 philosophy always has bucked this approach. Instead, buy less and build best-ofbreed
open and converged networks has been the model. Force10 allows for a 2-tier model of
core/distribution and access. Less equipment means lower capex and opex expenses as well as a
lower number of networking points of failure. Customers can design their networks with standardsbased
protocols and features without the need to worry about whether features will be disabled /
unsupported. We have the confidence to allow our customers to build interoperable, multi-vendor
networks based on standards. Inter-dependent features are based on standards. Customers can
change features/products without worrying about changing their network design or architecture.
Purpose of This Document
The purpose of this document is to help Dell Force10 SEs and customers integrate Dell Force10
equipment into legacy Cisco networks.
Table 1 : Dell Force 10 vs. Cisco Features
Cisco Proprietary
Feature
Dell Force10
Feature
Standard
Available? Notes
PVST+, RPVST PVST No Full interoperability
CDP LLDP
VTP GVRP
ISL 802.1Q
VMPS
802.1X + Mac-
Auth Bypass**
IEEE
802.1AB
IEEE
802.1p
IEEE
802.1D
Extension
of IEEE
802.1X
Higher scalability & extensibility with LLDP
Extensible - built on top of GARP
ISL has greater header overhead
Cisco supports 802.1X + Mac-Auth-Bypass
extension
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CGMP IGMP
EIGRP OSPF Yes
PAgP LACP
RFC 1112,
2236
IEEE
802.3ad
Cisco supports IGMP on all platforms
Force10 recommends OSPF
Cisco also supports OSPF
Cisco supports LACP
HSRP VRRP RFC 2238 Cisco supports VRRP
Netflow sFlow RFC 3176 More scalable
Cisco POE IEEE 802.3af
VTP
IEEE
802.3af
Cisco switches and new IP phones support
the IEEE standard
Force10 systems can operate in VTP transparent mode, passing traffic on untagged VLANs. Thus,
Force10 systems can co-exist with VTP-enabled networks. Force10 recommends deploying the
standards-based GVRP protocol.
VTP packets are passed untagged. Therefore, depending on the configuration, the FTOS native VLAN
or portmode hybrid capability may be required to pass such packets. The portmode hybrid command
sets a physical port or port-channel to accept both tagged and untagged frames.
FTOS Release 7.7.1.0 introduces native VLAN capability on physical interfaces, and FTOS Release
8.2.1.0 extends this to port-channel interfaces. In other words, starting with these releases, FTOS
transparently bridges VTP packets over physical and port-channel interfaces, allowing VTP to run
between devices connected to an FTOS switch/router.
Figure 1 : VTP Basic Test Setup
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In this sample configuration, port-channel 1 and port-channel 2 are added to VLAN 100 as tagged,
while remaining in VLAN 1 as untagged. Untagged traffic arrives at port-channel 1 and is flooded out
Gigabit Ethernet interface 6/47 or port-channel 2.
Figure 2: Port Channel FTOS Screenshot
interface Port-channel 1
no ip address
portmode hybrid
switchport
channel-member GigabitEthernet 6/0
no shutdown
!
interface Port-channel 2
no ip address
portmode hybrid
switchport
channel-member GigabitEthernet 6/47
no shutdown
!
interface vlan 100
tagged port-channel 1-2
E-Series#show vlan
FTOS Configuration
Codes: * - Default VLAN, G - GVRP VLANs, P - Primary, C - Community, I - Isolated
Q: U - Untagged, T – Tagged x - Dot1x untagged, X - Dot1x tagged G - GVRP tagged, M - Vlan-stack
NUM Status Description Q Ports
* 1 Active U Po1(Gi 6/0)
U Po2(Gi 6/47)
100 Active T Po1(Gi 6/0)
T Po2(Gi 6/47)
Spanning Tree Protocols
Dell Force 10 switches running FTOS support the different standard based spanning tree flavors such
as MSTP, RSTP, and PVST. These three different spanning tree variations are fully compatible with
other proprietary spanning tree extensions such as MST, PVST+, and RPVST+
The following section is divided into several scenarios:
• PVST (FTOS) and PVST+ (IOS)
• PVST (FTOS) and RPVST (IOS)
• RSTP and RPVST+
• MSTP
In our next revision, we aim to have two Catalyst 6509’s acting as root and backup root with dual
homed connections from the S4810’s. For now, the results obtained using the configuration on figure
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3, are clear enough to give us an idea of how the different spanning tree modes interact with each
other.
PVST (FTOS) and PVST+ (IOS)
Dell Force 10’s PVST’s implementation is fully compatible with Cisco’s IOS implementation. The
following setup will demonstrate how PVST can be deployed in a mixed environment.
In figure 3, we have a typical deployment where all devices are connected and potentially create a
loop if spanning tree was not configured. The Cisco Catalyst 6509 is the root bridge
Figure 3 : Dell Force 10 and Cisco Catalyst 6509 PVST+ Test Setup
PVST is enabled on the Dell Force 10 switches, whereas PVST+ is enabled on the Cisco switch. PVST is
the IEEE nomenclature, and PVST+ is Cisco’s equivalent to the IEEE’s PVST version.
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Switch Configuration
Figure 4 : S4810_1/2 Configuration
Figure 5 : S4810_1/2 PVST Configuration
In S4810_2, port 0/46 is blocking in an alternate role. The alternate role will switch to forwarding as
soon as the local root port fails.
All other ports are forwarding with the Cisco switch acting as the root switch for vlan 10. See figure 6.
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Figure 6 : Catalyst 6509 Configuration PVST+
Convergence Test:
1. Shutdown link between S4810_2 (Te0/47) and Catalyst 6509 (Te1/1).
Results:
IXIA traffic resumes in less than 2 seconds on link 0/46 on S4810_2. The blocking port moves to the
forwarding state as expected. This is because no interaction is needed with another switch, i.e. no
BPDU exchanged is needed.
2. Restore previous shutdown link between the S4810_2 and the Cisco Cat 6509.
Results:
IXIA traffic resumes 30 seconds later. This is as expected since the link between the S4810_2 and the
Cisco Catalyst 6509 go through the “listening” and “learning” states before moving onto the
“forwarding” state. Each state lasts 15 seconds and thus the 30 second traffic loss.
Note: PVST (FTOS) and RPVST+ (IOS) configuration was also tested and the results were identical to
that of PVST (FTOS) and PVST+ (IOS).
RSTP and RPVST+
Using the same test setup, RSTP and RPVST+ were enabled on the respective switches. For this
particular configuration, port 0/47 on S4810_2 assumes the alternate role and discarding status after
spanning tree settles down.
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Figure 7 : RSTP and PVST+ Setup
The same set of tests was performed and the results were as expected.
Switch Configuration
Figure 8 : S4810_1 Configuration
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Figure 9 : S4810_2 Configuration
Figure 10 : Catalyst 6509 Configuration
Convergence Test:
1. Shutdown link Te0/46 on S4810_2 and Te0/47 should take over with minimal traffic interruption.
Te0/47 is in discarding state as an alternate port to the root switch.
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Results:
As per the IEEE 802.1w standard, the alternate port took over as the root port transitioning from
discarding to learning and forwarding in less than 2 seconds.
2. Bring back port 0/46 and verify 0/47 goes back to being an alternate port role and discarding
state. Traffic should resume very quickly in less than 2 seconds.
Results:
Previously, with PVST and PVST+, reverting the process did not help in the traffic re-convergence
time. The forwarding port still had to go through the traditional spanning tree steps of listening,
learning and finally forwarding causing a 30 second traffic drop.
With RSTP, this did not take place. As expected, port Te0/47 moved to discarding state and port
Te0/46 transitioned to learning, and then forwarding in less than 2 seconds.
MSTP
MSTP was enabled on all the switches and allowed to converge. Port Te0/47 on S4810_2 is blocking
while Te0/46 on the same switch is forwarding. The same set of tests was performed where port
Te0/46 is shutdown and Te0/47 becomes active and traffic resumes under 2 seconds.
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Implementation Note
Some non-Dell Force10 systems which have hybrid ports participating in PVST+ transmit two kinds of
BPDUs: an 802.1D BPDU and an untagged PVST+ BPDU. The PVST+ BPDU is sent to perform
consistency checking and to inform all other potential Cisco switches about the native VLAN
configuration. Receiving switches consider only IEEE BPDUs for the native VLAN computations and
ignore the SSTP (Shared Spanning Tree Protocol) BPDUs.
Force10 systems do not expect either tagged or untagged PVST+ BPDUs on an untagged VLAN so
FTOS places the port in error-disable state by default when it receives this type of frame. This behavior,
while consistent with other vendors, might result in the network not converging.
To resolve this issue, which is documented in PR 84608, FTOS Release 8.2.1.0 introduces a CLI option
to set the error-disable state for receiving PVST BPDUs received on an untagged VLAN.
Force10 (conf-if-gi-4/0)# spanning-tree pvst err-disable cause invalid-pvst-bpdu
The FTOS default remains placing the port in an error-disable state if a tagged or untagged PVST
BPDU is received on an untagged VLAN.
Note: If VLAN 10 is untagged and an FTOS system receives a PVST BPDU with VLAN tag 20, the BPDU
is simply dropped.
Port Channels
Both FTOS and Cisco IOS support the Link Aggregation Control Protocol (LACP) for exchanging
information required to create a port-channel interface.
Figure 11 : Port Channel Setup
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Figure 12 : Port Channel Configuration
6509 Configuration C300 Configuration
interface TenGigabitEthernet1/3
switchport
switchport trunk encapsulation dot1q
switchport trunk allowed vlan 10-15,97-99
switchport mode trunk
no ip address
load-interval 30
spanning-tree portfast disable
channel-group 2 mode on
!
interface TenGigabitEthernet1/4
switchport
switchport trunk encapsulation dot1q
switchport trunk allowed vlan 10-15,97-99
switchport mode trunk
no ip address
load-interval 30
spanning-tree portfast disable
channel-group 2 mode on
interface TenGigabitEthernet 0/1
no ip address
no shutdown
!
interface TenGigabitEthernet 1/1
no ip address
no shutdown
!
interface Port-channel 2
description to-6509-Right
no ip address
switchport
spanning-tree pvst vlan 11 cost 200000
channel-member TenGigabitEthernet 0/1
channel-member TenGigabitEthernet 1/1
rate-interval 30
no shutdown
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