I was studying about BGP where it says
routes learned via ibgp are never propagated to other ibgp peers.
Does this mean that if we have say 4 routers in AS 6500.
Say we have R1 and R2 are nei and they exchange route between them.
Dos it mean that other 2 routers r3 and r4 will never learn routes from r1 and r2?
Assuming you have R1/R2/R3/R4, and they are all iBGP neighbors within as 6500....
If R1 learns a route from R2 - R1 will not advertise that route to R3 or R4. This is why mesh is required within iBGP - or you must use route reflectors.
The main purpose behind this is loop prevention.
When you say mesh required yiu mean all 4 routers should have physical connection
to each other?
Yes, thats what he's saying. All routers should have a "Full mesh" connection to eachother in order to propogate locally originated or learned routes. Only option I know of is a route reflector like mentioned above.
Many thanks for reply
Need to learn lot from you guys.
No, they do not need physical connections - they need to have a full mesh of iBGP peering. Whether they physically connect into a switch, or daisy chain through routers....the underlying IGP needs to support the TCP connectivity required by BGP to form the peering.
Something to keep in mind - iBGP does not have the same strict TTL requirements in their peer creation criteria that eBGP does.
Thanks for reply again
its clear to me now.
No problem - glad we could get it cleared up for you!