[c-nsp] BGP Next hop tracking / 'hold down' route...

[Phil Mayers]

On 06/25/2013 07:16 AM, Saku Ytti wrote:
> On (2013-06-24 23:19 -0500), Andrew Brant wrote:
>
>> 	neighbor 192.168.25.7 fall-over route-map RTM-BGP-FALLOVER
>
> Fall-over and next-hop tracking are two distinct features.
> With next-hop tracking, you simply invalidate the next-hops there by
> invalidating the routes and choosing next-best option.
> With fall-over you tear down whole session, this is usually undesirably
> large hammer, consider your IGP flap is very short, if you tore down the
> iBGP it might take minutes to recover.

You can simulate the desirable option using EEM and route tracking. Put 
a track object for the iBGP peer /32s with appropriate down/up delays, 
and an EEM or TCL script to "clear ip bgp x.x.x.x" when those track 
objects trigger.

It's a shame you can't do this directly:

  neighbour x.x.x.x track 50

I can imagine other use-cases.