From: Brian Dennis (bdennis@internetworkexpert.com)
Date: Fri Aug 19 2005 - 21:44:40 GMT-3
First off normally it's not the router-id you peer with but a loopback
interface's IP address.
Have you thought of why it's common to peer between loopbacks for iBGP?
If you answer this you should be able to answer the reason why it's
common to peer with an interface for eBGP.
Basically the idea is that you have multiple routes between iBGP peers
and you want the iBGP peering session to remain up when one of the
routes is unavailable. With eBGP you normally do not want the peering
session to stay up when your interface to the neighbor is down. The
exception is of course when you have multiple connections to that
neighbor (i.e. two T1's). As always there are always exceptions to this
but these are the common reasons.
HTH,
Brian Dennis, CCIE #2210 (R&S/ISP-Dial/Security)
bdennis@internetworkexpert.com
Internetwork Expert, Inc.
http://www.InternetworkExpert.com
Toll Free: 877-224-8987
Direct: 775-745-6404 (Outside the US and Canada)
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Ed Tan
Sent: Friday, August 19, 2005 4:50 PM
To: ccielab@groupstudy.com
Subject: BGP neighbor
Hi group,
I know it is a good practice to point the IBGP neighbor to the
neighbor's
router-id (instead of the interface address). I want to know why we
always
use the interface address as EBGP neighbor rather than the router-id?
Thanks,
Ed
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