internet routing table in a vrf

Fri Mar 8 23:09:08 UTC 2013

On Mar 8, 2013, at 5:55 PM, Saku Ytti <saku at ytti.fi> wrote:

> On (2013-03-08 18:17 +0000), Matt Newsom wrote:
> 
>>     If you run PIC and hide the next hop information between a loopback which is what will happen in a vpn environment
> 
> Typical SP network has next-hop-self in INET BGP, and does not carry
> edge-links in IGP. You don't want to have lot of prefixes in IGP.
> 
>> If the remote PE has PIC running he can bounce that traffic back to his backup path via another PE.
> 
> PIC merely makes sure that FIB is hierarchical and it guarantees all
> prefixes sharing next-hop converge at same time.
> Local-repair can be done with or without PIC, as it just means you have
> local information how to deliver frame to alternate destination without
> expectation of convergence.

Unfortunately Cisco made things confusing by naming their "BGP FRR" feature "BGP PIC Edge."

> 
>> There will be some percentage of your traffic that will then form a transient micro loop though because that remote PE will have his primary path through the failed link due to shortest as path length etc
> 
> Only if egress PE does IP lookup, which is typically does not do
> (per-prefix or per-ce, default config in 7600, JunOS, IOS-XR) as egress PE
> label adjacency entry has egress rewrite information.
> The faulted edge PE can local-repair and get frame delivered without having
> to wait for BGP to converge for the customer. Transient loop can occur if
> both of the edges have faulted.
> 
> -- 
>  ++ytti
> 