BGP issue

Unanswered Question
Sep 6th, 2007

I have 3 routers A,B,C connectied in Triangle ,ebgp running between A->C and A->B.Router A on top have BGP peer with AS 34846(ISP 1) and B,C have bgp peer with AS 3356(ISP2) ,All user are connected through router B and C.

I made the chage below on router B to preffer AS 34846 towards ISP1 for prefix 43.252 4.0/22, but it still Preferring path AS 3356 ISP2. All 3 routers gets 0/0 route from my both ISP. Please advise.

RouterB#

router bgp 10753

no synchronization

bgp log-neighbor-changes

network 43.252.0.0 mask 255.255.252.0

network 43.252.4.0 mask 255.255.252.0

network 43.252.156.0 mask 255.255.252.0

neighbor 43.252.0.6 remote-as 34846

neighbor 95.50.116.53 remote-as 3356

neighbor 43.252.0.6 route-map LP in

neighbor 95.50.116.53 route-map AS out

maximum-paths 3

default-metric 100

no auto-summary

ip access-list standard LP

permit 43.252.4.0 0.0.3.255

route-map AS permit 10

match ip address LP

set as-path prepend 10753 10753 10753 10753

!

route-map AS permit 20

route-map LP permit 10

match ip address LP

set local-preference 200

!

route-map LP permit 20

W8-7200-CC-1#sh ip bgp

BGP table version is 140628,

Status codes: s suppressed, d damped, h history, * valid, > best, i - internal

Origin codes: i - IGP, e - EGP, ? - incomplete

Network Next Hop Metric LocPrf Weight Path

* 0.0.0.0 43.252.0.6 0 34846 4589 i

*> 95.50.16.53 0 3356 i

* 43.252.4.0/22 43.252.0.6 25625856 200 0 34846 i

*> 0.0.0.0 100 32768 i

*> 43.252.12.0/24 43.252.0.6 0 0 34846 i

*> 43.252.152.0/22 43.252.1.250 100 32768 i

* 43.252.156.0/22 43.252.0.6 25625856 200 0 34846 i

*> 0.0.0.0 100 32768 i

Regards,

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robert.ward Thu, 09/06/2007 - 01:55

I am slightly confused by what you are doing.

* 43.252.4.0/22 43.252.0.6 25625856 200 0 34846 i

Is in your routing table from a peer yet you have the network statement in your BGP which you would not do if you were accepting a prefix from a peer.

Are you advertising the prefix to the peers or accepting it.

also are you running iBGP as LP only works within an AS and if your redistributing BGP into an IGP or anything similar then LP wont have any use. I see no iBGP config in your BGP config.

mohammedrafiq Thu, 09/06/2007 - 02:26

Hi,

On router B, I am advertising 43.252.4.0/22.

yes there is no IBGP between A,B and C because on B and c my AS is 10753 and on router A we have new AS 34846, so I peer A with B and C by ebgp. so now I want this prefix to in/out through ISP1 which has ebgp peering on rputer A.

I hpoe its clear up.

Regards,

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