internet routing table in a vrf

Fri Mar 8 22:55:32 UTC 2013

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.

> 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