Link state monitoring in Cisco switches

[omerar123]

Hi all,

I am looking for a feature in Cisco switches, which allows coupling interfaces (physical ports) to be bound together, such that a change in the link state of one interface, will result in the same change on the other interface.

For example:

Ports Eth1/1 and Eth1/2 are bound to each other. if Eth1/1 goes down, Eth1/2 will go immediately down, and once Eth1/1 goes up again, Eth1/2 will go up as well.

Is there such feature? if so, which models support it?

Thanks in advance,

Omer.

[Philip D'Ath]

What model switch is this?

I don't think you can easily.  You would have to use an event action script or something similar.

[omerar123]

I was afraid this will be the answer. Are there any models that support a simple such feature in simple. 

[Amit Verma]

Hi Omer,

You can do that with the EEM Script. Please go the through the below link.

https://supportforums.cisco.com/document/117596/cisco-eem-basic-overview-and-sample-configurations

[pille1234]

That really depends on your exact use case. Out of my head I could think of several different aproaches to your request:

• Link-State-Tracking feature for Catalyst and Nexus 4000 - you could easily bring down a downlink port, when the corresponding uplink went down: Cisco Config Guide

• Are your bound interfaces Port-channels? Then use the lacp min-link-feature do bring the channel down
• Do the physical interfaces need to go down or could route-manipulation help as well? Then use IP SLA and line protocol tracks. Two separate tracks could be connected with an AND-statement, allowing the track do go down once the first link is gone
• As already mentioned: use EEM. Not as difficult as you might think:
• track 1 interface e1/1 line-proto
• event manager applet BRING-IF2-DOWN
• event track 1 state down
• action 1.0 cli command "conf t"
• action 2.0 cli command "int e1/2"
• action 3.0 cli command "shut"
• same is needed for the other interface.

Hope that helps,

best regards