[c-nsp] VRF randomly, stably install only one from multiple route sets

[Oliver Boehmer (oboehmer)]

everton at lab.ipaccess.diveo.net.br
<mailto:everton at lab.ipaccess.diveo.net.br> wrote on Friday, January 07,
2005 9:06 PM:

> Oliver Boehmer (oboehmer) wrote:
>> 
>> You might want to check the "import" option to
>> ibgp-multipath. This way we'll import more paths
>> into the VRF and we can fail-over to alternate
>> paths without waiting for the periodic import-scan.
> 
> I have found this:
> 
>   The import keyword allows the network operator
>   to configure the VRF table to accept multiple
>   redundant paths in addition to the best path.
>   This feature should be used when there are multiple
>   paths with identical next hops available to ensure
>   optimal convergence times. A typical application of
>   this configuration option is to configure redundant
>   paths in a network that has multiple route reflectors
>   for redundancy.
> 
> Would this work for equal prefixes exported from
> VRFs hosted at different PEs? I'm afraid here in
> our case we have mostly different next hops pointing
> to distinct PEs.

It also works in this case, i.e. multiple PE's advertising the same IPv4
prefix with different RD's.

> A difficulty ibgp-multipath-import option does
> not seem to address is the unstable routes R1
> temporarily taking over stable routes R2 as the
> router PE1 oscillates between up and down.

You are right, it only avoids waiting 15 secs for the next import-scan..

	oli