[c-nsp] How to bring one link down if another related link goes down

[John Neiberger]

On Mon, Sep 27, 2010 at 5:22 PM, Phil Mayers <p.mayers at imperial.ac.uk> wrote:
> On 09/28/2010 12:12 AM, John Neiberger wrote:
>>
>> We have two ten gig links between a pair of 7600s. For a couple of
>> reasons, if one goes down we need the other to go down automatically
>> in order to force traffic to take a completely different path instead
>> of trying to cram all of our traffic down the remaining link.
>>
>> My first thought was to use an Etherchannel with min-links set to 2.
>> However, there are architectural reasons why we may not be able to use
>> Etherchannels in this particular situation. If we can't use
>> Etherchannels, what other methods are there?
>>
>> Is there some way to utilize some sort of object tracking to force one
>> link to go down if its partner goes down? Alternatively, the link
>
> Probably the "best" option is an EEM applet. Something like:
>
> track 20 interface TenGigabitEthernet1/3 line-protocol
>  delay down 1 up 30
> event manager applet TEST
>  event track 20 state down
>  action 1.0 cli command "enable"
>  action 1.1 cli command "conf t"
>  action 1.2 cli command "int Te1/1"
>  action 1.3 cli command "shut"
>
> ...typed from memory so read the docs for more info.

That may be the best idea I've seen. It wouldn't even be necessary for
it to bring the links back up automatically. If one link goes down,
we're going to need to do a lot of careful troubleshooting before we
bring it up, so a manual restoration process would be best.

Thanks!