[c-nsp] Internet in VRF

[Adam Vitkovsky]

Hi Dan,

> Dan Peachey
> Sent: 05 May 2015 13:38
> 
> >
> > > I don't know why PIC would be required - I don't see any need for
> > > sub-second convergence of Internet prefixes (and more than a single FIB
> > > entry for an Internet prefix). I'm sure someone will come along with a
> > use
> > > case... :)
> > >
> > Not sure what the exact numbers for ASR9k are but on MX960 It takes
> around
> > a minute to reprogram next hops for 500k prefixes.
> > Hence my earlier assumption that some just don't care since its Internet
> > service.
> >
> > adam
> >
> 
> I should have said "I don't know why PIC Edge would be required". PIC Core
> on the other hand is a no brainer (enabled by default on the ASR9K I
> believe).

I guess PIC edge is more important as it provides fast failover (local-repair) towards the PE with alternate AS-Exit in case the link providing the primary AS-Exit fails, so while the BGP converges slowly and majority of the PEs are still forwarding traffic towards the node acting as primary AS-Exit the traffic is not dropped by this node but forwarded towards the backup AS-Exit node. 
Whereas BGP PIC core provides fast failover in cases where the whole PE router fails (which is less likely to happen) so when other PEs in the AS are notified via IGP that the primary NH is not reachable anymore there's no need to wait for the FIB to be reprogramed -so the convergence is as fast as the IGP (hence the need to tune LSA/LSP propagation). 

I'm not sure it's enabled by default as I guess you'd still need to use the "additional-paths selection route-policy" under the vpnv4 AF to program the backup NH into the FIB. 
 
adam

  
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