eBGP multihop

FIGURE 8 . 1 4 eBGP multihop
This configuration will not work as it is set up currently. We need to set the update source
on R1 and R3. We also need to set up eBGP multihop on each of those devices:
R1#conf t
Enter configuration commands, one per line. End with CNTL/Z.
R1(config)#router bgp 100
R1(config-router)#neighbor 3.3.3.3 update-source Lo0
R1(config-router)#neighbor 3.3.3.3 ebgp-multihop
R1(config-router)#^Z
R1#
R3#conf t
Enter configuration commands, one per line. End with CNTL/Z.
AS 200
AS 100
20.20.20.0 /30
.1
.1
S0
S0
.2
.2
S1
S0
10.10.10.0 /30
R3
R1 R2
R2 is not
running BGP.
268 Chapter 8  Border Gateway Protocol
R3(config)#router bgp 200
R3(config-router)#neighbor 1.1.1.1 update-source Lo0
R3(config-router)#neighbor 1.1.1.1 ebgp-multihop
R3(config-router)#^Z
R3#
With the addition of the update-source and ebgp-multihop keywords, this BGP configuration
will now work. Now that you’ve configured a BGP network, we need to turn our focus
to injecting routes into BGP