eBGP Multihop

[imstha001]

We are trying to establish eBGP multi hop but it is not working.

HEre is the sample config.

router bgp 1111
bgp log-neighbor-changes
neighbor 208.110.23.246 remote-as 2222
neighbor 208.110.23.246 ebgp-multihop 5
neighbor 208.110.23.246 update-source TenGigabitEthernet0/3/0.1504
!
address-family ipv4
neighbor 208.110.23.246 activate
neighbor 208.110.23.246 default-originate
neighbor 208.110.23.246 prefix-list default out
exit-address-family

BR2.204CSK#sh ip bgp sum

BGP activity 2739026/2089994 prefixes, 23865204/22726463 paths, scan interval 60 secs

Neighbor             V              AS            MsgRcvd MsgSent TblVer InQ OutQ     Up/Down        State/PfxRcd
208.110.23.246 4             2222          0                      0 0 1 0 0                                  never           Active

and log is showing as following.

Mar 10 16:22:59: BGP: 208.23.47.246 open failed: Connection timed out; remote host not responding

Mar 10 16:22:59: BGP: 208.23.47.246 Active open failed - tcb is not available, open active delayed 14336ms (35000ms max, 60% jitter)

Mar 10 16:22:59: BGP: ses global 208.23.47.246 (0x7F8B5FB6D260:0) act Reset (Active open failed).

Mar 10 16:22:59: BGP: 208.23.47.246 active went from Active to Idle

Mar 10 16:22:59: BGP: nbr global 208.23.47.246 Active open failed - open timer running

Mar 10 16:22:59: BGP: nbr global 208.23.47.246 Active open failed - open timer  running

Please suggest me what might be the issue.

[Julio E. Moisa]

Hi

eBGP multihop is used between eBGP routers only when you aren't using the directly connected subnet, have you verified if both routers have configured the ebgp-multihop and if there are 5 hops or less to reach the remote route ? You could verify if the update-sources are configured correctly or if you are able to ping them from each other.

Hope it is useful

:-)

[imstha001]

Thanks Moisa

[Julio E. Moisa]

You are welcome,

Hope this information was useful

:-)

[Raja_D]

Hi,

As you are trying to establish ebgp neighborship with ebgp peer which is at remote far end and on different subnet you need to configure static routing towards the neighbor ip by adding a static route entry from the source router pointing to the next hop wan ip that is in the middle of the ebgp peer.

Example:

R1->R2->R3

Suppose you are trying to form ebgp neighborship between R1 and R3

R1 interface ip configured as 192.168.12.2 which is connecting to R2 and inturn R2 interface connecting to R3 which as ip set as 192.168.23.3

then from R1 you need to configure static route to R3 as given below and vice versa from R3 to R1

R1(config)#ip route 192.168.23.3 255.255.255.255 192.168.12.2

R3(config)#ip route 192.168.12.1 255.255.255.255 192.168.23.2