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
More Related VSS Configuration on Cisco Switches
