Are you using an IGP as well? If not then maybe you should. Also bear in minf that iBGP has an AD of 200, so it will lose to IGPs, while eBGP has only 20.
It would help to see your configs though ... Tarek -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Hunt Lee Sent: Wednesday, March 27, 2002 5:26 PM To: [EMAIL PROTECTED] Subject: BGP Next-Hop [7:39704] Team, I found an example of BGP "next-hop" Attribute from Internet Routing Arch (by Halabi) - Any explanation will be appreciate. Router A, B & C are all in the same AS, while Router D is in a separate AS. Not the best diagram :) Basically:- Router A & Router B are running IBGP Router B & Router D are running EBGP Router B is attached to a stub network (192.212.1.0 /24) Router D is attached to a stub network (128.213.1.0 /24) Router B is learning route 128.213.1.0 /24 from Router D Router B is also injecting route 192.212.1.0 /24 into BGP IBGP EBGP 2.2.2.2 1.1.1.1 A ---------------------------- B ----------------------D -----------------| 128.213.1.0 /24 Serial 0 \ / | \ / | \ / | \ / | \ / ------------ 3.3.3.3. \ / 192.212.1.0 /24 C I understand that in BGP table of Router A, it would have 2 entries:- Destination 192.212.1.0 /24 Next-hop: 2.2.2.2 (Next-hop is 2.2.2.2 since for IBGP sessions, the Next-hop will be the IP of the IBGP neighbor who advertised the route, which is Router B) Destination 128.213.1.0 /24 Next-hop: 1.1.1.1 (Next hop is 1.1.1.1 since for routes coming into an AS via EBGP, the next hop learned from EBGP is carried unchanged into IBGP - in this case, it's Router D). What I am confused it's the Routing Table of Router A, Destination 192.212.1.0 /24 Next-hop 2.2.2.2 (Best Route inserted from BGP table) - cool Destination 128.213.1.0 /24 Next-hop: 1.1.1.1 (Best Route inserted from BGP table) - cool Destination 3.3.3.0 /24 Next-hop: Directly Connected via Serial 0 - cool Destination 2.2.2.0 /24 Next-hop: 3.3.3.3 (why?? isn't this directly connected via IBGP, shouldn't it be directly connected?) Destination 1.1.1.0 /24 Next-hop: 3.3.3.3 (why?? shouldn't this have 2 routes, one via 3.3.3.3, and the other via 2.2.2.2?) Also, I thought that in such a scenario, one would want to make sure that every BGP Next-Hop can be reached via either IGP or static routes - However, Halabi says it's only needed for IBGP Next-hop, is it correct? Thanks, Hunt Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=39706&t=39704 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
