Another interesting weekend. I've begun in earnest my look into BGP. I am reading the usual suspects - Halabi, Stewart, and RFC 1771. Finally got a scenario set up with iBGP where all the routes are showing up where they belong. 1) The command Show IP BGP is proving quite useful to know. This appears to yield the contents of the BGP table, which may or may not have anything in common with the routing table. 2) The process of injecting routes into BGP now makes sense to me. Halabi actually explains it quite well on pages 134-135 ( 1st edition ) , and it really is no different than with any other routing protocol in the world of Cisco. But I guess I was more tired than I thought last night. It didn't sink through the first time. Outsmarted myself again ;-> 3) After a bit of fiddling with an inter-AS problem, I finally understood something in the RFC that had me a bit confused. Section 5.1.3 ( Next_Hop ) talks about the next hop router being on a common subnet with the peer and the advertiser. I was confused because a couple of days ago I had three routers talking to eachother via eBGP 9 different AS on each router ) with no problem. Last night I set up two AS's, one with three routers, one with one router. Router_1---router_2-----router_3------router_4 OSPF-------OSPF---------OSPF AS1-------------------------AS1------------AS4 IBGP------------------IBGP/EBGP-------EBGP The link between AS1 and AS4 refused to come out of the ACTIVE state. Turns out that my use of the neighbor a.b.c.d update-source loopback 0 was the problem. The loopback was not on the same subnet. I suppose that if I were to use the EBGP Multihop command, this would... naw that's not it. Just tested. Something else bad is happening. Or at least, ebgp-multihop does not seem to solve the problem of stuck-in-active when using neighbor a.b.c.d update-source loop 0 on both sides Eliminating the update-source does allow the Established state to form. Now if I could only determine why AS4 is seeing only BPG routes that originate on routers 3 and 2... :-< 4) Even in this small lab, BGP appears to take an inordinate amount of time to set up and stabilize after a Clear IP BGP * command. I can imagine what it must take on a router that receives a full BGP table ( 90,000 routes according to the last Tony Bates CIDR report ) 5) There seems to be a bit more to learn. regards Chuck Please check out my new footers for a new age 1) Altruism http://www.hungersite.com/ Please help feed hungry people worldwide. A few seconds a day can make a difference to many people 2) Shameless Commerce http://www.certificationzone.com An excellent source for information, study materials, practice questions, practice exams, and practice labs. Applicable for all levels of certification, as well as the attainment of internetworking expertise. Tell them Chuck Larrieu sent you. ( disclaimer - I will receive addition free months membership when enough people mention my name upon joining ) ___________________________________ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
