From: Manjeet Chawla (mchawla@xxxxxxxxxx)
Date: Tue Jul 06 1999 - 14:29:13 GMT-3
Hi !
On the router RB under Router BGP put the command
Neigh <IP Address of RA (facing RB)> next-hop-self.
The reason is, RC,RD and RE have no idea how to get to RA, the next hop
in BGP table. Remember to CLEAR IP BGP <neigh address> to reset the bgp
and new changes to take affect.
Other way is to run IGP on RB, RC and RD and on the link between RA and
RB. Make the IGP passive between RA and RB.
I like the Next-hop-self better as in real life it's better if you can't
assume that your ISP will be able to run IGP.
Good Luck
-Manjeet Chawla
Scott O'Donnell wrote:
> Hello,
> I hope I can explain this.
>
> I have setup five routers RA,RB,RC,RD,RE (left to right). All routers
> are connected in a row via serial links.
>
> Like this: RA ------ RB ------ RC ------- RD ------- RE
>
> I have the links assigned subnets as follows:
> RA->RB = 4.4.4.0/24
> RB->RC = 3.3.3.0/24
> RC->RD = 2.2.2.0/24
> RD->RE = 1.1.1.0/24
>
> RA is assigned and running BGP AS 400
> RB,RC,RD are assigned and running BGP AS 100, IBGP connections fully
> meshed.
> RE is assigned and running BGP AS 200
>
> RE is originating network 128.213.1.0/24 with a network command
> "Network 128.213.0.0"
> RD learns the 128.213.0.0 route and places it in it's table with the
> next hop as 1.1.1.1 (RE)
> RC learns the 128.213.0.0 route in it's BGP table (SHO IP BGP) but
> doesn't place it in the route table.
> RB learns the 128.213.0.0 route in it's BGP table (SHO IP BGP) but
> continues to display a console
> message "BGP: no valid path for 128.213.0.0/16" .
>
> Both RC and RB have routes in their route table for network 1.0.0.0/8
>
> rB#sho ip bgp
> BGP table version is 39, local router ID is 200.200.200.5
> 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
> *>i1.0.0.0 2.2.2.2 0 100 0 i
> *>i2.0.0.0 2.2.2.2 0 100 0 i
> *>i3.0.0.0 2.2.2.1 1 100 0 i
> *> 110.0.0.0 4.4.4.4 0 0 400 i
> * i128.213.0.0 1.1.1.1 0 100 0 200 i
> *>i192.212.1.0 2.2.2.2 0 100 0 i
>
> sho ip route
> R 1.0.0.0/8 [120/2] via 3.3.3.3, Serial0
> R 2.0.0.0/8 [120/1] via 3.3.3.3, Serial0
> 3.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
> S 3.0.0.0/8 is directly connected, Null0
> C 3.3.3.0/24 is directly connected, Serial0
> 4.0.0.0/24 is subnetted, 1 subnets
> C 4.4.4.0 is directly connected, Ethernet0
> B 110.0.0.0/8 [20/0] via 4.4.4.4
> R 192.212.1.0/24 [120/2] via 3.3.3.3, Serial0
>
> Why doesn't RB learn about the 128.213.0.0 network in AS 200?
>
> Am I missing the big picture?
>
> Scott
>
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