Wednesday, September 3, 2014

VSS Configuration on Cisco 6500

The Virtual Switching System (VSS) allows two Cisco Catalyst 6500 or 4500 chassis to bond together so that is seen as a single virtual switch to the rest of the network. Other devices will see the VSS configured 6500 as a single device which means it’s possible to use multi chassis ether channel and protocols like spanning-tree will only see a single switch. This article provides configuration that will allow you to easily enable VSS on these switches.

While a similar technology (Multi-Chassis Etherchannel, MEC) exists in Nexus datacenter switches known as vPC, the Nexus switches only appear to other adjacent switches as one switch across L2 links while maintaining two separate control planes and management points. VSS actually does a better job of emulating a single switch with one active, and one (or more) standby control plane allowing it to fully support a dual-homed L3 routed link. If you are familiar with Cisco Stackwise technology in 3750/3850 switches, VSS is probably more comparable to those except VSS only supports up to two switches and instead of using Stackwise cables, it uses multiple 10G links for interconnecting switches (i.e. VSL).



















Requirements
  • Virtual Switching Supervisor 720-10GE (VS-S720-10GE-3C and VS-S720-10GE-3CXL) with IOS 12.2(33)SXH1 and IP Base
  • or Supervisor 2T (VS-S2T-10G and VS-S2T-10G-XL) with IOS 12.2(50) SY and IP Base
Note: Please check Cisco documentation for more detail

Cabling Between Chassis
  • Minimum of two 10Gbps links with at least one on the Supervisor
  • Minimum of one (more is recommended) 1Gbps or 10Gbps links for dual-active detection 

Dual Active Detection Method
There are three available options; BFD, Fast Hello, Enhanced PAgP. EPAgP requires a downstream switch that is EPAgP-capable, which is sometime hard to find. BFD requires an IP address to be configured on the interface. Here we choose to use Fast Hello, although more than one method can be configured.

Configuration Steps:
Make sure all cabling between two switches are completed before proceeding
On Switch 1
1. Set switch number to 1
!
switch set switch_num 1 local
switch read switch_num local ! confirm 1 is returned
!

2. Configure virtual domain then save config
!
configure terminal
switch virtual domain 1
 switch 1
 mac-address use-virtual  ! optional but recommended
!
do wr mem
!

3. Configure VSL links. 
!
interface Port-channel 1
 desc --- To Switch 2 VSL ---
 switchport
 switch virtual link 1
 no shut
!
interface range TenGigabitEthernetx/x-y ! modify as necessary
 channel-group 1 mode on
 no shutdown
!
do wr mem
exit
!

4. Convert switch to VSS mode. Confirm and switch will reload
!
switch convert mode virtual
!

On Switch 2
1. Set switch number to 2
!
switch set switch_num 2 local
switch read switch_num local ! confirm 2 is returned
!

2. Configure virtual domain then save config
!
configure terminal
switch virtual domain 1
 switch 2
 mac-address use-virtual  ! optional but recommended
!
do wr mem
!

3. Configure VSL links. 
!
interface Port-channel 2 ! must be different number from switch 1
 desc --- To Switch 1 VSL ---
 switchport
 switch virtual link 2
 no shut
!
interface range TenGigabitEthernetx/x-y ! modify as necessary
 channel-group 2 mode on
 no shutdown
!
do wr mem
exit
!

4. Convert switch to VSS mode. Confirm and switch will reload
!
switch convert mode virtual
!
  • Wait until switch 2 comes back and join VSS
  • You can only make config changes on the active supervisor now

On the active switch
1. Adjust switch priority
!
configure terminal
switch virtual domain 1
 switch 1 priority 110
 switch 2 priority 100
!

2. Configure dual-active detection
!
switch virtual domain 1
 dual-active detection fast-hello
!
interface ra GigabitEthernet1/x/x ! modify as necessary
 desc --- VSL Fast Hello ---
 dual-active fast-hello
 no shutdown
!
interface ra GigabitEthernet2/x/x ! modify as necessary
 desc --- VSL Fast Hello ---
 dual-active fast-hello
 no shutdown
exit
!
show switch virtual dual-active fast-hello ! verify
!

Reference from http://www.labminutes.com/blog/2013/09/cisco-4500-4500x-6500-vss-configuration


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