BGP Question

[mahmoodmkl]

Hi Guys,

While going through the BGP chapters and docs it is mentioned that if u r a transit AS then run IBGP in full-mesh in u r AS to have better control of the routes.

Can anyone explain me why..?

Thanks in Advance.

Thanks

Mahmood

[Richard Burts]

Mahmood

There are probably several things that are reasons for this, but probably the most important reason for the requirement for full mesh is that a router running BGP will learn some prefixes from an IBGP neighbor and will not advertise those prefixes to another IBGP neighbor.

Perhaps a simple example may help. Think of an AS with 3 routers running BGP - rtrA. rtrB, and rtrC. So rtrB will learn some prefixes from rtrA. rtrB will not advertise those prefixes to rtrC. To learn those prfixes rtrC will need to peer with rtrA.

HTH

Rick