配置IP、ospf、bgp
[r1-LoopBack0]ip add 1.1.1.1 24
[r1-GigabitEthernet0/0/0]ip add 12.1.1.1 24
[r2-LoopBack0]ip add 2.2.2.1 24
[r2-GigabitEthernet0/0/0]ip add 12.1.1.2 24
[r2-GigabitEthernet0/0/1]ip add 23.1.1.1 24
[r3-LoopBack0]ip add 3.3.3.1 24
[r3-GigabitEthernet0/0/0]ip add 23.1.1.2 24
[r3-GigabitEthernet0/0/1]ip add 34.1.1.1 24
[r4-LoopBack0]ip add 4.4.4.1 24
[r4-GigabitEthernet0/0/0]ip add 34.1.1.2 24
[r4-GigabitEthernet0/0/1]ip add 45.1.1.1 24
[r4-GigabitEthernet0/0/2]ip add 54.1.1.1 24
[r5-LoopBack0]ip add 5.5.5.1 24
[r5-GigabitEthernet0/0/0]ip add 45.1.1.2 24
[r5-GigabitEthernet0/0/2]ip add 54.1.1.2 24
[r2]ospf 1 router-id 2.2.2.2
[r2-ospf-1]a 0
[r2-ospf-1-area-0.0.0.0]network 12.1.1.2 0.0.0.0
[r2-ospf-1-area-0.0.0.0]network 2.2.2.0 0.0.0.255
[r2-ospf-1-area-0.0.0.0]network 23.1.1.1 0.0.0.0
[r2-LoopBack0]ospf network-type broadcast
[r3]ospf 1 router-id 3.3.3.3
[r3-ospf-1]a 0
[r3-ospf-1-area-0.0.0.0]network 23.1.1.2 0.0.0.0
[r3-ospf-1-area-0.0.0.0]network 3.3.3.0 0.0.0.255
[r3-ospf-1-area-0.0.0.0]network 34.1.1.1 0.0.0.0
[r3]interface loo0
[r3-LoopBack0]ospf network-type broadcast
[r4]ospf 1 router-id 4.4.4.4
[r4-ospf-1]a 0
[r4-ospf-1-area-0.0.0.0]network 34.1.1.2 0.0.0.0
[r4-ospf-1-area-0.0.0.0]network 4.4.4.0 0.0.0.255
[r4-ospf-1-area-0.0.0.0]network 45.1.1.1 0.0.0.0
[r4-ospf-1-area-0.0.0.0]network 54.1.1.1 0.0.0.0
[r4-LoopBack0]ospf network-type broadcast
[r1]bgp 1
[r1-bgp]router-id 1.1.1.1
[r1-bgp]peer 12.1.1.2 as-number 2
[r1-bgp]ipv4-family unicast
[r1-bgp-af-ipv4]undo synchronization
[r1-bgp-af-ipv4]network 1.1.1.0 24
[r1-bgp-af-ipv4]peer 12.1.1.2 enable
[r2]bgp 2
[r2-bgp]router-id 2.2.2.2
[r2-bgp]peer 3.3.3.1 as-number 2
[r2-bgp]peer 3.3.3.1 connect-interface LoopBack 0
[r2-bgp]peer 4.4.4.1 as-number 2
[r2-bgp]peer 4.4.4.1 connect-interface LoopBack 0
[r2-bgp]peer 12.1.1.1 as-number 1
[r2-bgp]ipv4-family unicast
[r2-bgp-af-ipv4]undo synchronization
[r2-bgp-af-ipv4]network 2.2.2.0 24
[r2-bgp-af-ipv4]network 3.3.3.0 24
[r2-bgp-af-ipv4]peer 3.3.3.1 enable
[r2-bgp-af-ipv4]peer 3.3.3.1 next-hop-local
[r2-bgp-af-ipv4]pe
[r2-bgp-af-ipv4]peer 4.4.4.1 enable
[r2-bgp-af-ipv4]peer 4.4.4.1 next-hop-local
[r2-bgp-af-ipv4]peer 12.1.1.1 enable
[r3]bgp 2
[r3-bgp]router-id 3.3.3.3
[r3-bgp]peer 2.2.2.1 as-number 2
[r3-bgp]peer 2.2.2.1 connect-interface LoopBack 0
[r3-bgp]peer 4.4.4.1 as-number 2
[r3-bgp]peer 4.4.4.1 connect-interface LoopBack 0
[r3-bgp]ipv4-family unicast
[r3-bgp-af-ipv4]undo synchronization
[r3-bgp-af-ipv4]peer 2.2.2.1 enable
[r3-bgp-af-ipv4]peer 4.4.4.1 enable
[r4-ospf-1]bgp 2
[r4-bgp]router-id 4.4.4.4
[r4-bgp]peer 2.2.2.1 as-number 2
[r4-bgp]peer 2.2.2.1 connect-interface LoopBack 0
[r4-bgp]peer 3.3.3.1 as-number 2
[r4-bgp]peer 3.3.3.1 connect-interface LoopBack 0
[r4-bgp]peer 5.5.5.1 as-number 3
[r4-bgp]peer 5.5.5.1 ebgp-max-hop
[r4-bgp]peer 5.5.5.1 connect-interface LoopBack 0
[r4-bgp]ipv4-family unicast
[r4-bgp-af-ipv4]undo synchronization
[r4-bgp-af-ipv4]peer 2.2.2.1 enable
[r4-bgp-af-ipv4]peer 2.2.2.1 next-hop-local
[r4-bgp-af-ipv4]peer 3.3.3.1 enable
[r4-bgp-af-ipv4]peer 3.3.3.1 next-hop-local
[r4-bgp-af-ipv4]peer 5.5.5.1 enable
[r5]bgp 3
[r5-bgp]router-id 5.5.5.5
[r5-bgp]peer 4.4.4.1 as-number 2
[r5-bgp]peer 4.4.4.1 ebgp-max-hop
[r5-bgp]peer 4.4.4.1 connect-interface LoopBack 0
[r5-bgp]ipv4-family unicast
[r5-bgp-af-ipv4]undo synchronization
[r5-bgp-af-ipv4]network 5.5.5.0 24
[r5-bgp-af-ipv4]peer 4.4.4.1 enable
[r4]ip route-static 5.5.5.0 24 45.1.1.2
[r4]ip route-static 5.5.5.0 24 54.1.1.2
[r5]ip route-static 4.4.4.0 24 45.1.1.1
[r5]ip route-static 4.4.4.0 24 54.1.1.1
但是1-3的bgp表中没有5.5.5.1，就很怪，搞不懂