Figure 12: Using Ebgp-Multihop - Juniper JUNOSE 11.2.X BGP AND MPLS Configuration Manual

neighbor ebgp-multihop
Copyright © 2010, Juniper Networks, Inc.
external peers with the neighbor ebgp-multihop command because no direct connection
exists between them. Because router NY is not a BGP speaker, static routes are configured
on routers Boston and LA. The configuration for router NY is not shown, because it does
not involve BGP.

Figure 12: Using EBGP-Multihop

The following commands achieve the BGP configuration.
To configure router Boston:
host1(config)#ip route 10.7.4.0 255.255.255.0 10.1.10.2
host1(config)#router bgp 100
host1(config-router)#neighbor 10.7.4.3 remote-as 300
host1(config-router)#neighbor 10.7.4.3 ebgp-multihop
To configure router LA:
host2(config)#ip route 10.1.10.0 255.255.255.0 10.7.4.4
host2(config)#router bgp 300
host2(config-router)#neighbor 10.1.10.1 remote-as 100
host2(config-router)#neighbor 10.1.10.1 ebgp-multihop
Use to configure BGP to accept route updates from external peers in networks that
are not directly connected to the local peer.
If you specify a BGP peer group by using the peerGroupName argument, all the members
of the peer group inherit the characteristic configured with this command unless it is
overridden for a specific peer.
Any external BGP peering that is not resolved by a connected route is treated as a
multihop. Configurations with loopback-to-loopback external BGP peering require the
neighbor ebgp-multihop command to work properly. In these configurations, the
neighbor remote-as command is issued with the address of a loopback interface.
This command takes effect immediately and automatically bounces the BGP session.
Use the no version to return BGP to halt acceptance of such routers. Use the default
version to remove the explicit configuration from the peer or peer group and reestablish
inheritance of the feature configuration.
See neighbor ebgp-multihop
Chapter 1: Configuring BGP Routing
33