On Mar 8, 2013, at 5:55 PM, Saku Ytti <s...@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 >
