MPLS VPN design - RR in forwarding path?

Tony Varriale tvarriale at
Thu Jan 1 21:25:24 UTC 2015

On 12/31/2014 6:08 AM, Marcin Kurek wrote:
> Hi everyone,
> I'm reading Randy's Zhang BGP Design and Implementation and I found 
> following guidelines about designing RR-based MPLS VPN architecture:
> - Partition RRs
> - Move RRs out of the forwarding path
> - Use a high-end processor with maximum memory
> - Use peer groups
> - Tune RR routers for improved performance.
> Since the book is a bit outdated (2004) I'm curious if these rules 
> still apply to modern SP networks.
> What would be the reasoning behind keeping RRs out of the forwarding 
> path? Is it only a matter of performance and stability?
> Thanks,
> Marcin

Overall, depends on your design and scale.  But, I will comment on a few 
of your items...

We have RRs in the forwarding path but have a project to move them out 
in 2015.  We feel it gives us more options as well as more flexibility 
when we move to the next phase of RR design (hierarchical).

Most vendors today have the performance numbers (sometimes they aren't 
published publically) for routers acting as RRs.  Ask your vendor and 
pick one that suits you.  We generally buy the middle or most memory and 
pick a reasonable processor.  And, then we monitor :)

As for peer groups, you should have a design that allows you to herd 
most of the config snips together.  Use the features that make your life 
easier and allow you to simplify your routing policies.


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