BGP route question - need help

Hi,

We're dual homed to 2 isp running ebgp with 2 routeres. These 2 routers are running ibgp betweem them. ISP A - AS1000 & ISP B - AS 2000, my AS# is 9220.

ISP A (AS1000) ISP B (AS2000) | | | | rtr A --- IBGP ---- rtr B 210.18.45.3 AS 9220 210.18.45.126

Both rtr A & B are receiving full route from the upstream provider. My question is rtr B can receive full route (> 163000 routes) of two upstream provider. However, rtr A can receive very minimal route (less then 300 routes) from rtr B. Could any expert tell me if it's normal or not, why rtr A does not learn the full route from rtr B ? Is there any parameter missing ?

Here're two rtr config for your info :

RTR A

----- router bgp 9220 no synchronization bgp log-neighbor-changes bgp dampening network 210.18.45.0 aggregate-address 210.18.45.0 255.255.252.0 summary-only neighbor 212.46.26.7 remote-as 1000 neighbor 212.46.26.7 description pi 6Mbps connection neighbor 212.46.26.7 soft-reconfiguration inbound neighbor 212.46.26.7 route-map pi-bgp-in in neighbor 212.46.26.7 route-map pi-bgp-out out neighbor 212.46.26.7 filter-list 1 out neighbor 210.18.45.126 remote-as 9220 neighbor 210.18.45.126 description A01 neighbor 210.18.45.126 next-hop-self no auto-summary ip as-path access-list 1 permit ^$ ! route-map pi-bgp-in permit 10 set local-preference 200 set weight 10 ! route-map pi-bgp-out permit 10 set as-path prepend 9220 9220

RTR A#sh ip bgp summ

Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd

212.46.26.7 4 1000 14977712 755605 1076056 0 0 5d00h 163426 210.18.45.126 4 9220 683943 1264982 1076090 0 0 5d00h 128

RTR B

----- router bgp 9220 no synchronization bgp log-neighbor-changes bgp bestpath compare-routerid bgp dampening network 210.18.45.0 aggregate-address 210.18.45.0 255.255.252.0 summary-only neighbor 210.18.45.3 remote-as 9220 neighbor 210.18.45.3 description A02 neighbor 210.18.45.3 next-hop-self neighbor 201.77.45.197 remote-as 2000 neighbor 201.77.45.197 description AGC 6Mbps neighbor 201.77.45.197 send-community neighbor 201.77.45.197 soft-reconfiguration inbound neighbor 201.77.45.197 route-map AGC-bgp-in in neighbor 201.77.45.197 route-map AGC-bgp-out out neighbor 201.77.45.197 filter-list 1 out no auto-summary

ip as-path access-list 1 permit ^$ ! route-map AGC-bgp-out permit 10 set as-path prepend 9220 9220 ! route-map AGC-bgp-in permit 10 set local-preference 100 set as-path prepend 2000 2000

RTR B#sh ip bgp summ

Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd

210.18.45.3 4 9220 1210353 684039 1437788 0 0 5d00h 163321 201.77.45.197 4 2000 1072144 37860 1437784 0 0 5d00h 162811

Thanks :-)

Reply to
yellow
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I believe it's because router B only advertises routes that are better back to A. It knows that the best way to get to destination X is through itself as it can see both routes, so it sends that route over to A.

You could test this theory by looking at a route that is being advertised internally via iBGP and see which one is the best route, via ISP A or B.

If you lose ISP A, router A should receive all the routes.

Well, that's what I think!

Reply to
MA

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