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List:       isp-bgp
Subject:    [isp-bgp] Prefered to choose bigger network prefix avertised
From:       "Romie" <romie () indo ! net ! id>
Date:       2003-07-21 14:13:17
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Dear all,

I have 2 E-BGP peer sesion on my GW-Router(Router A) , one to AS
65500(Router B) , and another to AS 65400(Router C). Router B(AS 65500) and
Router C(AS65400) is directly connected each other and  make a E-BGP session
also.

Router B only advertise 1 (one) big prefix network 10.5.0.0/17 to me (Router
A), and advertised severals smaller prefix networks 10.5.0.0/17-22 to router
C ( see bgp table below) , since it advertise smaller networks prefix to
RouterC and  Router C advertised those smaller prefix networks to me (Router
A) , BGP on my router (Router A) prefer to choose 65400_65500 path compare
to 65500 path to reach 10.5.0.0/17-22 network.

What i want is , i would like to make 65500 as the best path , and
65400_65500 as the backup path to reach
10.5.0.0/17-22 network.

The condition is :
Adminitrator of Router B(AS65500)  cannot be pursued to advertised smaller
network prefix to my Router (Router A) as it does to router C .. , and also
on Router C. Both of those router is on its fix configuration , cannot be
changed.

Any one can help me to make that kind of BGP configuration on my Router
(Router A) ?
without using a static route " ip route 10.5.0.0/17 172.17.236.253 " applied
?

i mean it's dynamicly choose 65400_65500 path , when BGP session between me
(Router A) and Router B is down, and when the bgp between me(router A) and B
is estabilished again , then it back to choose 65500 path to reach
10.5.0.0/17-22 network.

Neighbor            V    AS MsgRcvd MsgSent   TblVer  InQ OutQ Up/Down
State/PfxRcd
172.17.236.253  4  65500   75054   74687    35499    0    0 1w4d
2                                    [Router B - AS65500)
192.168.63.154  4  65400  138994   74851    35499    0    0 4d04h
1365                                 [Router A - AS65400)



Network                          Next Hop            Metric LocPrf   Weight
Path

*> 10.5.0.0/17              172.17.236.253                               0
65500 i
*> 10.5.8.0/22              192.168.63.154                                0
65400 65500  i
> 10.5.12.0/22             192.168.63.154                                0
65400 65500 i
*> 10.5.16.0/22            192.168.63.154                                0
65400 65500 i
*> 10.5.20.0/22            192.168.63.154                                0
65400 65500 i
*> 10.5.28.0/22            192.168.63.154                                0
65400 65500 i

.                                            .
.              .
.                                            .
.              .
.                                            .
.              .

*> 10.5.124.0/22            192.168.63.154                                0
65400 65500 i



REgards,
Romie



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