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DELL Force10 Interoperability Guide
Interoperability Guide on Key Features
Dell Force10
Force10 Marketing Team
July 2012
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Dell Networking Confidential Internal use only
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THIS WHITE PAPER IS FOR INFORMATIONAL PURPOSES ONLY, AND MAY CONTAIN TYPOGRAPHICAL
ERRORS AND TECHNICAL INACCURACIES. THE CONTENT IS PROVIDED AS IS, WITHOUT EXPRESS
OR IMPLIED WARRANTIES OF ANY KIND.
2010 Dell Inc. All rights reserved. Reproduction of this material in any manner whatsoever without
the express written permission of Dell Inc. is strictly forbidden. For more information, contact Dell.
Dell, the DELL logo, and the DELL badge, PowerConnect, and PowerVault are trademarks of Dell Inc. Symantec and the SYMANTEC logo are trademarks or registered trademarks of Symantec Corporation or its affiliates in the US and other countries. Microsoft, Windows, Windows Server, and Active Directory are either trademarks or registered trademarks of Microsoft Corporation in the United States and/or other countries. Other trademarks and trade names may be used in this document to refer to
either the entities claiming the marks and names or their products. Dell Inc. disclaims any proprietary
interest in trademarks and trade names other than its own.
July 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 ............................................................................................... 5
Convergence Test: .................................................................................................. 7
Results: ................................................................................................................ 7
RSTP and RPVST+ ................................................................................................... 8
Switch Configuration ............................................................................................... 8
Convergence Test: ................................................................................................ 10
Results: .............................................................................................................. 10
MSTP ................................................................................................................. 11
Implementation Note .................................................................................................. 11 Miscellaneous ...................................................................................................... 12
Port Channels ............................................................................................................ 12
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 ................................... Error! Bookmark not defined. Figure 5 : S4810_1 Configuration ........................................................................ 8 Figure 6 : S4810_2 Configuration ....................................................................... 9 Figure 7 : Catalyst 6509 Configuration ................................................................. 9 Figure 8 : Port Channel Setup ........................................................................... 12 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 vendor-
driven 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-of-
breed 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 standards-
based 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 IEEE
802.1AB Higher scalability & extensibility with LLDP
VTP GVRP IEEE
802.1p Extensible - built on top of GARP
ISL 802.1Q IEEE
802.1D ISL has greater header overhead
VMPS 802.1X + Mac-
Auth Bypass**
Extension
of IEEE
802.1X
Cisco supports 802.1X + Mac-Auth-Bypass
extension
CGMP IGMP RFC 1112,
2236 Cisco supports IGMP on all platforms
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EIGRP OSPF Yes Force10 recommends OSPF
Cisco also supports OSPF
PAgP LACP IEEE
802.3ad Cisco supports LACP
HSRP VRRP RFC 2238 Cisco supports VRRP
Netflow sFlow RFC 3176 More scalable
Cisco POE IEEE 802.3af IEEE
802.3af
Cisco switches and new IP phones support
the IEEE standard
VTP 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
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.
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Figure 2: Port Channel FTOS Screenshot
FTOS Configuration
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
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 6509s acting as root and backup root with dual
homed connections from the S4810s. For now, the results obtained using the configuration on figure
3, are clear enough to give us an idea of how the different spanning tree modes interact with each
other.
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PVST (FTOS) and PVST+ (IOS) Dell Force 10s PVSTs implementation is fully compatible with Ciscos 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 and the Catalyst
4948 is the backup 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 Ciscos equivalent to the IEEEs PVST version.
Switch Configuration Figure 4 : S55_1 PVST status and configuration
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Figure 5 : S4810_2 PVST status and configuration
In S4810_2, port 0/47 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.
Figure 6 : Catalyst 6509 PVST+ status and configuration
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Figure 7 : Catalyst 4948 PVST status and configuration
Convergence Test: 1. Shutdown the link between S55_1 (Gi 0/47) and Catalyst 6509 (Gi 2/47). 2. Bring back up the link between S55_1 and Catalyst 6509.
Results: IXIA traffic resumes under a second on link Gi 0/42 on S55_1. The blocking port (Gi 0/42) moves to
the forwarding state as expected. This is because no interaction is needed with another switch, i.e. no
BPDU exchanged is needed.
IXIA traffic resumes 30 seconds later. This is as expected since the link between the S55_1 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.
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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 (See Figure 3), RSTP and RPVST+ were enabled on the respective switches.
For this particular configuration, port Gi 0/42 on S55_1 assumes the alternate role and discarding
status after spanning tree settles down.
The same set of tests was performed and the results were as expected.
Switch Configuration Figure 8 : S55_1 RSTP configuration and status
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Figure 9 : S4810_2 RSTP configuration and status
Figure 10 : Catalyst 6509 RPVST+ configuration and status
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Figure 11 : Catalyst 4948 RPVST+ configuration and status
Convergence Test: 1. Shutdown Gi 0/47 on S55_1 and measure length of time required for traffic to resume. 2. Recover Gi 0/47 on S55_1 and measure length of time required for traffic to resume.
Results: Shutting down Gi 0/47 on S55_1 caused very little traffic interruption. Less than a second for traffic to
resume with Gi 0/42 taking over as the root port towards the Catalyst 6509.
However, reverting the process caused a 30 second traffic interruption. This is attributed to the fact
that the Cisco switches are running per-vlan spanning tree instances a proprietary implementation of
RSTP and the Dell Force 10 devices are running a single spanning tree instance. For more details on
the protocol exchanges please see the Miscellaneous section of the document.
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MSTP MSTP was enabled on all the switches and allowed to converge. Port Gi 0/42 on S55_1 is blocking
while Gi 0/47 on the same switch is forwarding. The same set of tests was performed where port Gi
0/47 is shutdown and Gi 0/42 becomes active and traffic resumes under a second.
Gi 0/47 is brought back online and traffic and traffic resumes in under a second. Having all switches
be part of the same spanning tree instance improves the reconvergence times dramatically.
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 (Cisco proprietary BPDU packet). 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 (802.1D) 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)# no 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.
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Miscellaneous Additional documentation on spanning tree interoperability can be found at the following link.
http://salesedge/browse under Networking Dell Force 10 Dell Force 10 Whitepapers &
Technical Docs
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 12 : Port Channel Setup
Figure 13 : Static 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
http://salesedge/browse
Interoperability Guide on Key FeaturesDell Force10Force10 Marketing TeamJuly 2012IntroductionPurpose of This Document
VTPSpanning Tree ProtocolsPVST (FTOS) and PVST+ (IOS)Switch ConfigurationConvergence Test:Results:RSTP and RPVST+Switch ConfigurationConvergence Test:Results:MSTPImplementation NoteMiscellaneous
Port Channels
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