From: wsq (wsqccie@hotmail.com)
Date: Mon Sep 08 2003 - 07:47:49 GMT-3
it is better to paste your all configuration and show out
----- Original Message -----
From: "James Bone" <cciehead@yahoo.com>
To: <ccielab@groupstudy.com>
Sent: Sunday, September 07, 2003 2:36 AM
Subject: RE: bgp to non-bgp to bgp
> Ok, I picked up Mr. Halabis BGP book. Im not done reading all of them
> as yet. It was doing recursion as it was explained that is why the BGP
> route is flapping. More specifically the problem lies in the next hop as
> you said, thanks, and as shown below.
>
> routerc#sh ip route
> Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP
> D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
> N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
> E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
> i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS
> inter area
> * - candidate default, U - per-user static route, o - ODR
> P - periodic downloaded static route
>
> Gateway of last resort is not set
>
> 172.16.0.0/24 is subnetted, 2 subnets
> C 172.16.20.0 is directly connected, Serial0
> B 172.16.1.0 [20/0] via 172.16.1.2, 00:00:33
>
> routerc does not have any info how to get to 172.16.1.2 since the router
> between routerc and routerf is only running ospf. I was able to solved
> it using static routing.
>
> ip route 172.16.1.2 255.255.255.255 172.16.20.2.
>
> How to solve this another way without using static routing?
>
> Thanks in advance
>
>
>
> -----Original Message-----
> From: eward15@juno.com [mailto:eward15@juno.com]
> Sent: Tuesday, September 02, 2003 1:04 PM
> To: cciehead@yahoo.com
> Subject: Re: bgp to non-bgp to bgp
>
>
>
> Look at your routing table and your BGP table on routera to see where
> the next hop is. Chances are the next hop is unreachable, forcing the
> BGP entry to time out. The OSPF entry will be placed back into the
> routing table, only to give way to the "newly" discovered BGP entry,
> continuing the loop.
>
>
>
> Eugene Ward
>
>
>
>
>
> ------------------------------------------------------------------------
>
>
>
>
>
>
>
> Hello Group,
>
>
>
> I'm trying to understand why this is flapping.
>
>
>
> routera --------------routerb--------------------routerc
>
>
>
> routera is running BGP in AS 1
>
> routerb is running only OSPF. It cannot run BGP.
>
> routerc is running BGP in AS 2
>
>
>
> routera to routerb network is 172.16.20.0 mask 255.255.255.0
>
> routerb to routerc network is 172.16.1.0 mask 255.255.255.0
>
>
>
> On routerc, I advertised network 172.16.1.0 under bgp process using
> network
>
> 172.16.1.0 mask 255.255.255.0
>
>
>
> Routera receives the route, 172.16.1.0 and placed in its routing table
> as BGP
>
> learned route. However, it disappears every 60 seconds and the route
> becomes
>
> OSPF learned route. Eleminating BGP and running only OSPF works but I'm
> curious
>
> as to why this is happening. Can anyone explain why? Thanks in advance.
>
>
>
> Relevant Configuration follows
>
>
>
> routera
>
>
>
> ethernet 0
>
> 172.16.1.1 255.255.255.0
>
>
>
> serial 1
>
> clockrate 64000
>
> 172.16.20.2 255.25.255.0
>
>
>
> router ospf 10
>
> network 172.16.0.0 0.0.255.255 area 0
>
>
>
> ************************************************************
>
> routerc
>
>
>
> serial 0
>
> 172.16.20.1 255.255.255.0
>
>
>
> router osp 10
>
> network 172.16.0.0 0.0.255.255 area 0
>
>
>
> router bgp 1
>
> neighbor 172.16.1.2 remote-as 3
>
> neighbor 172.16.1.2 ebgp-multihop 2
>
> no auto-summary
>
>
>
> ************************************************************
>
>
>
> routerf
>
>
>
> ethernet 0
>
> 172.16.1.2 255.255.255.0
>
>
>
> router ospf 10
>
> network 172.16.0.0 0.0.255.255 area 0
>
>
>
> router bgp 3
>
> network 172.16.1.0 mask 255.255.255.0
>
> neighbor 172.16.20.1 remote-as 1
>
> neighbor 172.16.20.1 ebgp-multihop 2
>
> no auto-summary
>
>
>
>
>
>
>
>
>
>
>
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This archive was generated by hypermail 2.1.4 : Wed Oct 01 2003 - 07:24:24 GMT-3