From: Herbert Maosa (asawilunda@googlemail.com)
Date: Sat Aug 11 2007 - 10:45:17 ART
Hi,
BGP does not change the next hop on a Multi-access network unless explicitly
configured to do so through *next-hop self*. If the BGP speaker determines
that both the sending and the intended neighbor are reached through the
same interface, it leaves the next hop unchanged for optimum routing (
needless to make an extra unneccessary hop through this router ) as these
neighbors can reach each other directly on the multi-access network.
Herbert.
On 8/11/07, NITIN NITIN <ccie_study_123@yahoo.com> wrote:
>
> Hi experts,
>
>
> R5 and R1 and R2 are in a broadcast domain
> next hop is 152.1.125.2 for routes via R1
> DON't know why
> Please suggest ????????
>
> R5 - 152.1.125.5 ip
> R1 - 152.1.125.1 ip
> R2 - 152.1.125.2 ip
>
>
>
> Rack1R5#sh ip bgp regexp _254$
> BGP table version is 14, local router ID is 150.1.5.5
> Status codes: s suppressed, d damped, h history, * valid, > best, i -
> internal,
> r RIB-failure, S Stale
> Origin codes: i - IGP, e - EGP, ? - incomplete
> Network Next Hop Metric LocPrf Weight Path
> * 205.90.31.0 152.1.125.2 0 200 254 ?
> *> 152.1.125.2 0 200 254 ?
> * 220.20.3.0 152.1.125.2 0 200 254 ?
> *> 152.1.125.2 0 200 254 ?
> * 222.22.2.0 152.1.125.2 0 200 254 ?
> *> 152.1.125.2 0 200 254 ?
> Rack1R5#
>
>
>
> R5 in AS 100
>
> R1 and R2 in AS 200
> R5
> router bgp 100
> no synchronization
> bgp router-id 150.1.5.5
> bgp log-neighbor-changes
> neighbor 150.1.4.4 remote-as 100
> neighbor 150.1.4.4 update-source Loopback0
> neighbor 152.1.125.1 remote-as 200
> neighbor 152.1.125.2 remote-as 200
> no auto-summary
> !
>
> R1
> router bgp 1000
> no synchronization
> bgp router-id 150.1.1.1
> bgp log-neighbor-changes
> bgp confederation identifier 200
> bgp confederation peers 3000
> neighbor 152.1.123.3 remote-as 3000
> neighbor 152.1.125.5 remote-as 100
> no auto-summary
>
> R2
> router bgp 2000
> no synchronization
> bgp router-id 150.1.2.2
> bgp log-neighbor-changes
> bgp confederation identifier 200
> bgp confederation peers 3000
> neighbor 152.1.123.3 remote-as 3000
> neighbor 152.1.125.5 remote-as 100
> no auto-summary
>
>
> Regards
>
>
> ---------------------------------
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-- Kindest regards, hm
This archive was generated by hypermail 2.1.4 : Sat Sep 01 2007 - 11:32:10 ART