From: Rivron Francois (Francois.Rivron@xxxxxxxxx)
Date: Mon Nov 26 2001 - 06:00:52 GMT-3
FYI :
http://www.cisco.com/univercd/cc/td/doc/product/software/ios121/121cgcr/ip_r
/iprprt2/1rdbgp.htm#xtocid142341
To prevent the creation of loops through oscillating routes, the multihop
will not be established
if the only route to the multihop peer is the default route (0.0.0.0).
>From :
> -----Message d'origine-----
> De: John Neiberger [SMTP:neiby@excite.com]
> Date: lundi 26 novembre 2001 05:33
> @: Matt Smith; ccielab@groupstudy.com
> Objet: Re: Interesting BGP problem
>
> I just set this up and was able to verify it in 12.1(11). Without at
> least
> a specific classfull route in the routing table the neighbors would never
> get past ACTIVE. Here is the output from debug ip bgp:
>
> 09:24:03: BGP: 172.16.1.1 multihop open delayed 10064ms (no route)
> 09:24:13: BGP: 172.16.1.1 multihop open delayed 13920ms (no route)
> 09:24:14: BGP: Import timer expired. Walking from 1 to 1
> 09:24:27: BGP: 172.16.1.1 multihop open delayed 14560ms (no route)
> 09:24:29: BGP: Import timer expired. Walking from 1 to 1
> 09:24:35: BGP: compute bestpath
> 09:24:41: BGP: 172.16.1.1 multihop open delayed 14720ms (no route)
> 09:24:44: BGP: Import timer expired. Walking from 1 to 1
> 09:24:56: BGP: 172.16.1.1 multihop open delayed 10144ms (no route)
>
> On this router I then added a static route to 172.16.0.0 and the neighbors
> came up. Very interesting! This definitely falls into the "Good to Know"
> category.
>
> Thanks,
> John
>
> On Sun, 25 Nov 2001 20:02:24 -0500, Matt Smith wrote:
>
> | Hey all,
> | I just got done doing some last minute BGP practice scenarios in
> preperation
> | for my upcoming date with fate on 11/30. At any rate I was making some
> quick
> | and dirty lab scenarios to test some varios configurations and I found
> the
> | following
> |
> | R1 <----->R2<------->R3
> |
> | R1 is configured with a 0.0.0.0 route to R2 and R3 with a 0.0.0.0 route
> to R2
> | as well. I pinged from R1 to R3 and communicationed worked fine.
> |
> | Now I issued router bgp 100 on both R1 and R2 and defined the neigh bor
> | statements for iBGP.
> |
> | The BGP relationship never came up. AS#s were correct on both router
> | processes and neighbor statements and the IP addresses were correct as
> well.
> |
> | show ip bgp neighbor reports that neither router has sent or recieved
> and
> BGP
> | messages and a deb ip packet verifies that this is true.
> |
> | What was the culprit? well........... Make a guess then read on
> |
> |
> |
> |
> |
> |
> |
> |
> |
> |
> |
> |
> |
> |
> |
> |
> |
> |
> |
> |
> |
> | I issued a static route for the specific address of the neighbor on
> each
> | router (R1 and R3) pointing to R2 and the relationship came up.
> Apparently
> | BGP requires a route in the routing table for the nieghbor address and
> will
> | not use the 0.0.0.0 route. IP classless enabled on both routers and as
> I
> | stated both routers could ping one another. Has anyone ever read and
> | documentation supporting this to be true? I have never seen any rules
> | pertaining to this issue so I thouht I would share it with the group.
> Just a
> | quick tidbit. Hope it helps someone someday.
> |
> | Luck to All
> |
> | Matt Smith
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