From: Saul Arjona (saul.arjona.bueno@gmail.com)
Date: Mon Sep 03 2007 - 14:52:54 ART
For traffic going out from AS of R4 you could change either weight or Local
preference those two attributes are compared before MED.
regards
-Saul
On 9/3/07, dayo@ademuyiwa.com <dayo@ademuyiwa.com> wrote:
>
> HI Guys,
>
> Please i have a problem with IGP metric with BGP path selection. Please i
> will appreciate your comment
>
> How can I influence the path with the ebgp speaker with the highest IGP
> metric to talk to its ebgp neighbor to use its path for the BGP next hop.
>
> the bgp R4 below is using R6 3.3.6.6 (metric 3) with the lower metric to
> reach 200.20.102.1 But I need to influence R2 so that R4 will prefer it
> for
> the best.
>
> How can do it? because R4 is using IGP metric to choose its best path
>
> R2 and R6 area talking ebgp to R4.
>
>
> R4#sh ip bgp 200.20.105.1
> BGP routing table entry for 200.20.105.1/32, version 12
> Paths: (2 available, best #2, table Default-IP-Routing-Table)
> Flag: 0x820
> Advertised to update-groups:
> 1 2
> 20
> 3.3.2.2 (metric 20) from 3.3.2.2 (3.3.2.2)
> Origin IGP, localpref 100, valid, external
> 20
> 3.3.6.6 (metric 3) from 3.3.6.6 (3.3.6.6)
> Origin IGP, localpref 100, valid, external, best
> R4#
>
>
> R4#sh ip bgp 200.20.102.1
> BGP routing table entry for 200.20.102.1/32, version 14
> Paths: (2 available, best #1, table Default-IP-Routing-Table)
> Flag: 0x920
> Advertised to update-groups:
> 1 2
> 20
> 3.3.6.6 (metric 3) from 3.3.6.6 (3.3.6.6)
> Origin IGP, localpref 100, valid, external, best
> 20
> 3.3.2.2 (metric 20) from 3.3.2.2 (3.3.2.2)
> Origin IGP, metric 0, localpref 100, valid, external
> R4#
>
>
>
> R4#sh ip bgp
> BGP table version is 14, local router ID is 3.3.4.4
> 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
> *>i200.10.101.1/32 3.3.1.1 0 100 0 i
> *>i200.10.103.1/32 3.3.3.3 0 100 0 i
> *> 200.10.104.1/32 0.0.0.0 0 32768 i
> *> 200.20.102.1/32 3.3.6.6 0 20 i
> * 3.3.2.2 0 0 20 i
> * 200.20.105.1/32 3.3.2.2 0 20 i
> *> 3.3.6.6 0 20 i
> * 200.20.106.1/32 3.3.2.2 0 20 i
> *> 3.3.6.6 0 0 20 i
> R4#
>
>
>
> router bgp 10
> no synchronization
> bgp router-id 3.3.4.4
> bgp log-neighbor-changes
> network 200.10.104.1 mask 255.255.255.255
> neighbor 3.3.1.1 remote-as 10
> neighbor 3.3.1.1 update-source Loopback0
> neighbor 3.3.1.1 route-reflector-client
> neighbor 3.3.2.2 remote-as 20
> neighbor 3.3.2.2 ebgp-multihop 20
> neighbor 3.3.2.2 update-source Loopback0
> neighbor 3.3.3.3 remote-as 10
> neighbor 3.3.3.3 update-source Loopback0
> neighbor 3.3.3.3 route-reflector-client
> neighbor 3.3.6.6 remote-as 20
> neighbor 3.3.6.6 ebgp-multihop 20
> neighbor 3.3.6.6 update-source Loopback0
> no auto-summary
>
>
>
> R2#
>
> router bgp 20
> no synchronization
> bgp router-id 3.3.2.2
> bgp log-neighbor-changes
> network 200.20.102.1 mask 255.255.255.255
> neighbor 3.3.4.4 remote-as 10
> neighbor 3.3.4.4 ebgp-multihop 20
> neighbor 3.3.4.4 update-source Loopback0
> neighbor 3.3.4.4 next-hop-self
> neighbor 3.3.4.4 route-map good in
> neighbor 3.3.4.4 route-map got out
> neighbor 3.3.5.5 remote-as 20
> neighbor 3.3.5.5 update-source Loopback0
> neighbor 3.3.6.6 remote-as 20
> neighbor 3.3.6.6 update-source Loopback0
> no auto-summary
> !
>
> R6#
>
> router bgp 20
> no synchronization
> bgp router-id 3.3.6.6
> bgp log-neighbor-changes
> network 200.20.106.1 mask 255.255.255.255
> neighbor 3.3.2.2 remote-as 20
> neighbor 3.3.2.2 update-source Loopback0
> neighbor 3.3.4.4 remote-as 10
> neighbor 3.3.4.4 ebgp-multihop 20
> neighbor 3.3.4.4 update-source Loopback0
> neighbor 3.3.5.5 remote-as 20
> neighbor 3.3.5.5 update-source Loopback0
> no auto-summary
> !
> thanks
>
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