[c-nsp] Add-Path Selection on IOS-XE (maybe also on other platforms)

[Christian]

Hi list,

considering my following situation, which seems to me pretty ordinary:

Two RRs responsible for a domain of iBGP clients.

Two iBGP clients share for redundancy reasons the same customer via eBGP,
sometimes also by other protocols or even just statics/connected networks
of customers.

Now when those RRs receive and send all possible paths to all iBGP clients,
each customer is represented with four prefixes on the receiving client:
two next-hops, and two RRs = four paths.

Now, the problem is that I can't figure out how to install a proper backup
path. The paths are redundant in terms of next-hop, yes. But they are not
in terms of the Route-Reflector. This means that both, the best
and backup/repair path are both used from the RR with the smaller IP
address. Consequently, when a RR fucks up or just in case you need to flap
the BGP sessions by adding/remove address-families for example, there is no
fast convergency, as both paths from the same RR are programmed in the FIB
while prefixes learned from the remaining RR session are not programmed.

Is there any mechanism I'm apparently missing to make the criteria of
redundant advertiser/RR also a criteria of redundancy/PIC?

In case that this is not considered in IOS, what is an alternative approach
to make use of add-path by considering this?

Thanks / Kind regards
Chris