Cisco Catalyst 6500 User Manual
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Cisco Catalyst 6500 Virtual Switching System
Deployment Best Practices
Document ID: 109547
Components Used
When removing the preempt commands in Catalyst 6500 Series Switches in VSS Mode, will it reload the
This document provides best practices for Cisco Catalyst 6500 Virtual Switching System (VSS) 1440
deployment scenarios.
This document provides modular configuration guidance. Therefore, you can read each section independently
and make changes in a phased approach. This document assumes a basic comprehension and familiarity with
the Cisco IOS® Software user interface. The document does not cover overall network design.
There are no specific requirements for this document.
Components Used
This document is not restricted to specific software and hardware versions.
The information in this document was created from the devices in a specific lab environment. All of the
devices used in this document started with a cleared (default) configuration. If your network is live, make sure
that you understand the potential impact of any command.


Table of Contents

Summary of Contents for Cisco Catalyst 6500

  • Page 1: Table Of Contents

    SPAN Miscellaneous Frequently Asked Questions Can dual supervisors be used in each chassis with VSS? When removing the preempt commands in Catalyst 6500 Series Switches in VSS Mode, will it reload the switches? Related Information Introduction This document provides best practices for Cisco Catalyst 6500 Virtual Switching System (VSS) 1440 deployment scenarios.
  • Page 2: Conventions

    Use default Hello and Dead timers for EIGRP / OSPF protocols when you run in a VSS environment. • If you run the system with modular Cisco IOS software, it is recommended to go for larger value OSPF Dead timer.
  • Page 3 EXEC command in order to enable the synchronization. This mac−address−table synchronize command is available from Cisco IOS Software Releases 12.2(18)SXE4 and later. After you enable it, it is possible to still see entries that are not present in PFC or DFC. However, the module has a way to learn it from others that use Ethernet Out of Band Channel (EOBC).
  • Page 4 % Recommended aging time for all vlans is atleast three times the activity interval Dist−VSS# clear mac−address−table dynamic % MAC entries cleared. Dist−VSS# show mac−address−table synchronize statistics MAC Entry Out−of−band Synchronization Feature Statistics: −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−− Switch [1] Module [4] −−−−−−−−−−−−−−−−−−−−− Module Status: Statistics collected from Switch/Module : 1/4 Number of L2 asics in this module...
  • Page 5 Refer to Traffic on the VSL for more information. Recommendations • Always dual−home devices connected to VSS. • Always bundle VSL EtherChannel in the power of 2, because it has better hash results for optimized traffic load−sharing. • Redundancy of the VSL is still critical along with resiliency of VSL links. •...
  • Page 6: Upstream Link Recovery

    Upstream Link Recovery The recovery of upstream links (links to the core) can be attained through either MultiChassis EtherChannel (MEC) or the Equal Cost MultiPath (ECMP) feature. MEC convergence is consistent and independent of the number of routes. Whereas, ECMP convergence is dependent on the number of routes.
  • Page 7 MultiChassis EtherChannel A MultiChassis EtherChannel is an EtherChannel with ports that terminate on both chassis of the VSS. A VSS MEC can connect to any network element that supports EtherChannel, such as a host, server, router, or switch. At the VSS, an MEC is an EtherChannel with additional capability. The VSS balances the load across ports in each chassis independently.
  • Page 8: Vsl Link Loss And Recovery

    VSL Link Loss and Recovery If the VSL fails, the standby chassis cannot determine the state of the active chassis. In order to ensure that switchover occurs without delay, the standby chassis assumes the active chassis has failed and initiates switchover to take over the active role.
  • Page 9 IP Bidirectional Forwarding Detection (BFD) †Uses BFD messaging over a backup Ethernet connection. IP BFD uses a direct connection between the two chassis and does not require support from a neighbor switch. This method is available in Cisco IOS Software Release 12.2(33)SXH1 and later.
  • Page 10 OSPF Convergence with Default timers Recommendations • Enable atleast two links in VSL. • Use MEC with ePAgP or MEC with VSLP Fast Hello for faster VSL link loss convergence results. • Enable ECMP with IP−BFD. • Enable ePAgP to core, if the access layer is not ePAgP capable. •...
  • Page 11: Redundancy With Service Modules

    Service module support is a key requirement in order to position the VSS in the enterprise campus and enterprise data center market. The list of service modules that are supported in the Virtual Switch System are: Minimum Service Module Minimum Cisco IOS Module Release Release Network Analysis Module 12.2(33)SXH1...
  • Page 12: Multicast

    • VSL carries traffic under normal and failover scenarios, VSL bandwidth must be tuned accordingly. Refer to Integrate Cisco Service Modules with Cisco Catalyst 6500 Virtual Switching System 1440 for more information on service module integration. Multicast The IPv4 multicast protocols run on the active supervisor engine.
  • Page 13: Qualtiy Of Service

    • MEC is recommended in L3 and L2 environment to provide deterministic convergence. • MEC eliminates Reverse Path Forwarding (RPF) recalculation during any MEC link failure. • Egress replication with local enhancement for higher multicast replication throughput. • Egress replication requires DFCs for optimized replication performance. •...
  • Page 14: Span

    ports provides the same QoS results. Hardware Queuing Trust Receive Transmit Queue Mode Mode Queue VSL on uplinks †non−10G only (default) 1p3q4t 8q4t (DWRR/SRR) VSL on uplinks †10G only 1p7q4t 2q4t (DWRR/SRR) VSL across 1p3q4t uplinks and [non−10G] line cards (DWRR/SRR) 2q4t...
  • Page 15: Miscellaneous

    • VSL cannot be configured as SPAN destination. • VSL cannot be configured as source of RSPAN, ERSPAN, or Tx only local SPAN. • VSL header is removed by SPAN destination port before packet is transmitted out, and hence cannot be captured in the sniffer traces.
  • Page 16: Frequently Asked Questions

    The write erase command erases the startup−config and ROMMon variables. VSS requires switch−id ROMMon variable in order to boot in VSS mode. • Do not use preemption. Refer to Cisco recommends that you do not configure switch preemption for more information. •...
  • Page 17: Related Information

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