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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.

Commands

The command structure consists of 3 steps:

  1. define a link state group
  2. define upstream interfaces to the link state group
  3. define downstream interfaces to the link state group

Define Link State Group

Switch(config)# link state track 1

Define Upstream

Switch(config)# interface range gigabitethernet 0/1
Switch(config-if)# link state group 1 upstream

Define Downstream

Switch(config-if)# interface range gigabitethernet 0/2-10
Switch(config-if)# link state group 1 downstream

Show Commands

show link state group 1
show link state group detail

About the Author

RDonato

R Donato

Rick Donato is the Founder and Chief Editor of Fir3net.com. He currently works as a Principal Network Security Engineer and has a keen interest in automation and the cloud.

You can find Rick on Twitter @f3lix001