Hi, I'm hoping someone can help with this. I have two edge routers (A, B) running eBGP to two separate peers (1, 2) within my colo facility. I have a single Catalyst 4500 w/ dual Sup II's, acting as my core switch, which is connected to routers A, B. I am running EIGRP in my LAN, and I am redistributing the default gateways into EIGRP. My question is in order to run iBGP between my edge routers, do I need a direct physical connection between them, or can my colo provider somehow do multi-hop iBGP for me between them?
iBGP - physical connection needed between peers?
Nov 11, 2006
4 Replies
iBGP doesn't require a direct connection between peers, it supports multi-hop automatically. This is because the default configuration of iBGP is a full mesh of all the routers in the AS, but there's no expectation that there will be a physical full mesh.
Thanks for the reply. I've heard about issues with syncronization problems between iBGP and eBGP, which suggest there may be issues using multi-hop iBGP. Are you aware of any such problems?
ibgp does not change the next hop address (to get it to, you will need to use the neighbor x.x.x.x next-hop-self command) ibgp will not advertise ibgp learnt routes to ibgp neighbours (unless you do something fancy like route-reflect).
i think what you are getting at is the issue of turning sync off and having a non-bgp speaker in the path -- that router will need to know (via IGP) how to get to the ibgp-learnt prefixes.
SysAdm
Got it. Thanks for the help!
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