Virtual Switching System - VSS
Few Points to remember:
- In Simple terms, VSS is to combine multiple Cisco Catalyst switches into one virtual Switch.
- The data plane of both clustered switches is active at the same time in both chassis.
- For Control plane only one switch will be active and other will be standby.
- In VSS, If one Chassis fails, the other one will take overwithout any downtime.
- It eliminates STP.
- This is supported both in Catalyst 6500 and 4500 series switches.
- Need to make sure that peer VSS switch needs to be same hardware and software version..
Click here to know the Hardware requirements
Below Diagram shows the traditional method (Without VSS):
Here we are running PVSTP and HSRP on both the Layer3 switches, where traffic is load balanced.
Example: Vlan10, Switch1 is Root bridge and all traffic is sent to switch1.
after which Switch1 is Active for HSRP vlan:10, it will route accordingly
We use VSL(dedicated 10Gig links) is an Ether Channel interface which connects between the chassis.
This will transfer both data and control traffic.
This Link is responsible for Statefull switchover without any downtime.
Switch-1(config)#switch virtual domain 100 --->The switch virtual domain number should be unique
Switch-1(config-vs-domain)#switch 1
Switch-1(config-vs-domain)#exit
Switch-1(config)#interface port-channel 10
Switch-1(config-if)#switchport
Switch-1(config-if)#switch virtual link 1
Switch-1(config-if)#no shutdown
Switch-1(config-if)#exit
Configure Virtual Switch Link:
Switch-1(config)#interface range tenGigabitEthernet 1/1-2 ------>these links connects to Switch2
Switch-1(config-if)#channel-group 10 mode on
Switch-1(config-if)#no shutdown
Switch-1(config-if)#channel-group 10 mode on
WARNING: Interface TenGigabitEthernet1/1,2 placed in restricted config mode. All extraneous configs removed!
Switch-1(config)#exit
Switch-1#switch convert mode virtual ---->Execute the command, but do not reload until VSS configuration is completed on Switch 2
Switch 2 Virtual Domain and Port Channel Configuration:
Switch-2(config)#switch virtual domain 100
Switch-2(config-vs-domain)#switch 2
Switch-2(config-vs-domain)#exit
Switch-2(config)#interface port-channel 20
Switch-2(config-if)#switchport
Switch-2(config-if)#switch virtual link 2
Switch-2(config-if)#no shutdown
Switch-2(config-if)#exit
Configure Virtual Switch Link:
Switch-2(config)#interface range tenGigabitEthernet 1/1-2
Switch-2(config-if)#channel-group 20 mode on
Switch-2(config-if)#no shutdown
Switch-2(config-if)#channel-group 20 mode on
WARNING: Interface TenGigabitEthernet1/1,2 placed in restricted config mode. All extraneous configs removed!
Switch-2(config)#exit
Switch-2#switch convert mode virtual
At this point, console into Switch-1 . You will be prompted to save the work and confirm the switch reboot. Do the same for Switch-2.
After the reboot, verify the VSS configuration:
After the VSS configuration and restart, both switches start to function as one. One switch is designated as the Active and the other as the Standby switch
Switch-1#sh switch virtual
Executing the command on VSS member switch role = VSS Active, id = 1
Switch mode : Virtual Switch
Virtual switch domain number : 100
Local switch number : 1
Local switch operational role: Virtual Switch Active
Peer switch number : 2
Peer switch operational role : Virtual Switch Standby
Executing the command on VSS member switch role = VSS Standby, id = 2
Switch mode : Virtual Switch
Virtual switch domain number : 100
Local switch number : 2
Local switch operational role: Virtual Switch Standby
Peer switch number : 1
Peer switch operational role : Virtual Switch Active
Switch-1#
Commands:
redundancy reload shelf --->to reload the switch after enter it asks whether switch 1 or switch 2 to be reloaded.
redundancy force-switchover ----->switchover from active to passove viceversa.
show run switch 1---> will show the part of the config that is specific to switch 1.
show run switch 2---> will show the part of the config that is specific to switch 2.
show switch virtual--->to verify status of VSS
mac-address-table synchronize--->this is by default turned on. else enable it
show redundancy---->to see redundancy
redundancy, mode sso--->make sure redundancy mode is SSO
If we need standby console then issue below command from active switchSwitchVSS#(config)#redundancy
SwitchVSS#(config-red)#main-cpu
SwitchVSS#(config-r-mc)#standby console enable
