[c-nsp] why are packets not following the more specific route - xr 4.1.2 (asr9k)

[Ross Halliday]

> There are a good many ways to deal with this. What you need to do is read
> up and make sure you understand what the labels are actually pointing to
> and what that means for the forwarding process, especially on a hardware
> platform like your endpoint in question.
> 
> This isn't one of those tell me how to do it problems, but one of those
> you
> need to understand the architecture so you can know what you want to do on
> your network to fix it. I would love to help more, but you haven't given
> enough information to offer suggestions on solutions, and honestly, you're
> probably better off deciding them yourself since you know your network
> better than anyone here would anyway.

This is pretty good advice. Like Saku said, one of the advantages of MPLS is that the exit PE's only involvement is a simple "pop the label and do X" where X is something like "transmit on interface Gi9/9 VLAN 9". This is why, at least on platforms like 6500, very few features work. Think egress QoS, ACLs, logging, etc.

I think Penultimate Hop Popping may be an option in some cases.

We're happily running 4628 routes in our general customer VRF (subscribers, blackholes, and a 0/0) with RTBH for managing nasties. Our smallest PE is a 7200 NPE-225.

Cheers
Ross