[c-nsp] iBGP questions

[David Freedman]

> - Our current network is multihomed with a few upstream providers. Internally 
> we run a meshed iBGP session between our core network devices. In the core we 
> have two Catalyst switches that are trunked with each other (for VLAN 
> purpose). Do we need to run iBGP session between them too?
> 

You didn't say if these devices were core "switches" (i.e not used for 
routing in the general scheme of things) or hybrid switch/routers 
(running L3)

Do customers on the 1st Catalyst have connectivity at L3 to the rest of 
the network via the 2nd Catalyst (and vice versa) ?

If you are passing traffic through a device at L3 on the way to anywhere 
else in your network the other device will require some form of 
reachability information, be it anything from a default route to a full 
IP routing table (via iBGP).

If your devices are core routers and these core routers are supposed to 
hold a full routing table then they will need to speak iBGP, preferably 
directly to eachother (via a full mesh) to facilitate efficient update 
distribution, but other designs are possible.

Its all dependant on your design, but generally this is the case.

Dave.