Border Gateway Protocol - CCIE Routing and Switching Exam Certification Guide - page 432

eBGP versus iBGP Figure 9-3

AS 200

AS 100

AS 300

eBGP

eBGP eBGP

iBGP

AS 500

Figure 9-4

eBGP Multihop Peers

eBGP peers

AS 200

AS 100

E0 E0

Router A
loopback0: 1.1.1.1

Router B
E0: 2.1.11.1

Router C
E0: 2.1.10.1

Router D
loopback0: 2.1.1.1

The configurations of Router A and Router D in Figure 9-4 follow. Routers B and C are config-
ured with static routes (or run on IGP) to provide connectivity between Routers A and D.

Router A's configuration is shown in Example 9-2.

Router A Configuration Example 9-2

interface loopback 0
ip address 1.1.1.1 255.255.255.255
!
router bgp 100
neighbor 2.1.1.1 remote-as 200
neighbor 2.1.1.1 ebgp-multihop
neighbor 2.1.1.1 update-source loopback0
!
ip route 2.1.1.1 0.0.0.0 2.1.11.1