[c-nsp] general question on VRFs and FIBs...

[Robert Raszuk]

Hi Keegan,

> over another.  However, if the vrf's all have separate tables in the real
> world then that should require the table lookup to come before the prefix
> lookup.  If not there would be no way to figure out which fib to search.

For packets coming from customer (CE) there is no need for any 
additional lookup as switching vectors of the interfaces 
(logical/physical) are already locked to a given VRF.

/* One exception of the above is Policy Based VRF selection where you 
are choosing VRF dynamically based on preconfigured policy or even 
remote radius lookup. in this configuration interfaces are not bounded 
to any VRF. */

For packets coming from the core to a PE the VPN label directly points 
to the right VRF (per vrf label/aggregate label case). For per CE or per 
prefix labels no IP lookup is necessary in the VRFs at all for packets 
going to the CE.

Thx,
R.