User Manual

BGP Configuration Examples

214 Enterasys X-Pedition User Reference Manual

EBGP Multihop Configuration Example

EBGP Multihop refers to a configuration where external BGP neighbors are not connected to the

same subnet. Such neighbors are logically, but not physically connected. For example, BGP can be

run between external neighbors across non-BGP routers. Some additional configuration is required

to indicate that the external peers are not physically attached.

This sample configuration shows External BGP peers, X-Pedition1 and X-Pedition4, which are not

connected to the same subnet.

The CLI configuration for router X-Pedition1 is as follows:

Physical Link

Legend:

Peering Relationship

X-Pedi

16.122.128.1/16

X-Pedi

AS-64800

AS-64801

X-Pedi

16.122.128.3/16

17.122.128.3/16

17.122.128.4/16

18.122.128.3/16

18.122.128.2/16

bgp create peer-group ebgp_multihop autonomous-system 64801 type external

bgp add peer-host 18.122.128.2 group ebgp_multihop

! Specify the gateway option, which indicates EBGP multihop. Set the

! gateway option to the address of the router that has a route to the

! peer.

bgp set peer-host 18.122.128.2 gateway 16.122.128.3 group ebgp_multihop