Link State Tracking
Link State Tracking is a feature (within Cisco Switches) that binds the link state of multiple interfaces. This provides the ability to "down" interfaces based upon the link state of upstream interfaces.
The diagram below shows a simple of example of an scenario where link state tracking would be required. As you can see from the diagram if interface e0/0 was to go down (on either switch) unless the corresponding e0/1 link state was also changed to down, the server would continue to send traffic via the switch that has the downed upstream link.
The command structure consists of 3 steps:
- define a link state group
- define upstream interfaces to the link state group
- define downstream interfaces to the link state group
Define Link State Group
Switch(config)# link state track 1
Switch(config)# interface range gigabitethernet 0/1
Switch(config-if)# link state group 1 upstream
Switch(config-if)# interface range gigabitethernet 0/2-10
Switch(config-if)# link state group 1 downstream
show link state group 1
show link state group detail