!R1
conf t
int loopback 1
ip addr 1.1.1.1 255.255.255.255
no sh
int g0/0
ip addr 10.1.12.1 255.255.255.0
no sh
router bgp 1
network 1.1.1.1 mask 255.255.255.255
network 10.1.12.0 mask 255.255.255.0
neighbor 10.1.12.2 remote-as 2
neighbor 10.1.13.3 remote-as 3
exit
!R2
conf t
int loopback 1
ip addr 2.2.2.2 255.255.255.255
no sh
int g0/0
ip addr 10.1.12.2 255.255.255.0
no sh
int g1/0
ip addr 10.1.23.2 255.255.255.0
no sh
exit
router bgp 2
network 2.2.2.2 mask 255.255.255.255
network 10.1.12.0 mask 255.255.255.0
network 10.1.23.0 mask 255.255.255.0
neighbor 10.1.12.1 remote-as 1
neighbor 10.1.23.3 remote-as 3
exit
!R3
conf t
int loopback 1
ip addr 3.3.3.3 255.255.255.255
no sh
int g0/0
ip addr 10.1.23.3 255.255.255.0
no sh
int g1/0
ip addr 10.1.34.3 255.255.255.0
no sh
exit
router bgp 3
network 3.3.3.3 mask 255.255.255.255
network 10.1.23.0 mask 255.255.255.0
neighbor 10.1.12.1 remote-as 1
neighbor 10.1.23.2 remote-as 2
exit
設定為後,R1跟R2形成鄰居,R2跟R3形成鄰居,而R1跟R3卻沒有形成鄰居。
R3#show ip bgp summary
Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
10.1.12.1 4 1 0 0 0 0 0 never Idle