姓名：chanlsp (李树鹏)
拓扑：
需求：通过BGP的全互联使得R1的环回口和R5的环回口能够互相通信
配置方案：
1、在此配置设备的（IP地址省略）
2、R1和R2通过直连构建EBGP邻居关系
R1：router bgp 100
bgp log-neighbor-changes
neighbor 12.1.1.2 remote-as 200 //指定对端的邻居建立EBGP邻居//
R2：router bgp 200
bgp log-neighbor-changes
neighbor 12.1.1.1 remote-as 100
验证EBGP邻居关系;
R2#show ip bgp summary
BGP router identifier 22.1.1.1, local AS number 200
BGP table version is 1, main routing table version 1
Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
12.1.1.1 4 100 2 2 1 0 0 00:00:04 0
R1#show ip bgp summary
BGP router identifier 11.1.1.1, local AS number 100
BGP table version is 1, main routing table version 1
Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
12.1.1.2 4 200 7 7 1 0 0 00:04:27 0
3、在AS200区内运行IGP协议，使得R2、R3、R4能够通信。
R2:
router eigrp 90
network 22.0.0.0
network 23.0.0.0
R3:
router eigrp 90
network 23.0.0.0
network 33.0.0.0
network 34.0.0.0
R4:
router eigrp 90
network 34.0.0.0
network 44.0.0.0
4、R4和R5通过环回口建立EBGP邻居关系
R4：
router bgp 200
bgp log-neighbor-changes
neighbor 55.1.1.1 remote-as 300
neighbor 55.1.1.1 ebgp-multihop 2
neighbor 55.1.1.1 update-source Loopback0
R5：
router bgp 300
bgp log-neighbor-changes
neighbor 44.1.1.1 remote-as 200
neighbor 44.1.1.1 ebgp-multihop 2
neighbor 44.1.1.1 update-source Loopback0
这里环回口建议使用静态路由，使其通信
R5(config)#ip route 44.1.1.1 255.255.255.255 s1/2
R4的静态路由请按照R5自行配置即可
验证EBGP邻居关系：
R5#show ip bgp summary
BGP router identifier 55.1.1.1, local AS number 300
BGP table version is 1, main routing table version 1
Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
44.1.1.1 4 200 6 6 1 0 0 00:02:58 0
5、AS 200区域通过环回口建立IBGP邻居关系
R2:
router bgp 200
bgp log-neighbor-changes
network 22.1.1.1 mask 255.255.255.255
neighbor 12.1.1.1 remote-as 100
neighbor 33.1.1.1 remote-as 200
neighbor 33.1.1.1 update-source Loopback0
neighbor 33.1.1.1 next-hop-self
neighbor 44.1.1.1 remote-as 200
neighbor 44.1.1.1 update-source Loopback0
neighbor 44.1.1.1 next-hop-self
R3:使用最少的命令去构建邻居
这里采用的是peer-group对等体组
router bgp 200
synchronization
bgp log-neighbor-changes
bgp listen range 0.0.0.0/0 peer-group QYT
network 33.1.1.1 mask 255.255.255.255
neighbor QYT peer-group
neighbor QYT remote-as 200
neighbor QYT update-source Loopback0
R4:
router bgp 200
synchronization
bgp log-neighbor-changes
network 44.1.1.1 mask 255.255.255.255
neighbor 22.1.1.1 remote-as 200
neighbor 22.1.1.1 update-source Loopback0
neighbor 22.1.1.1 next-hop-self
neighbor 33.1.1.1 remote-as 200
neighbor 33.1.1.1 update-source Loopback0
neighbor 33.1.1.1 next-hop-self
neighbor 34.1.1.5 remote-as 300
neighbor 55.1.1.1 remote-as 300
neighbor 55.1.1.1 shutdown
neighbor 55.1.1.1 ebgp-multihop 2
neighbor 55.1.1.1 update-source Loopback0
R5：
router bgp 300
bgp log-neighbor-changes
network 55.1.1.1 mask 255.255.255.255
redistribute connected route-map conn
neighbor 34.1.1.4 remote-as 200
neighbor 44.1.1.1 remote-as 200
neighbor 44.1.1.1 ebgp-multihop 2
neighbor 44.1.1.1 update-source Loopback0
测试R2和R4的环回口通信：
R2(config-router)#do ping 44.1.1.1 sou lo0
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 44.1.1.1, timeout is 2 seconds:
Packet sent with a source address of 22.1.1.1
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 10/14/22 ms
另外在R4上配置ACL让R4能够匹配到55.1.1.1最优的这条路由
R4#show access-lists
Standard IP access list 10
10 permit 55.1.1.0, wildcard bits 0.0.0.255
最终验证R1可以ping通R5
R1#ping 55.1.1.1 sou lo0
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 55.1.1.1, timeout is 2 seconds:
Packet sent with a source address of 11.1.1.1
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 23/27/30 ms
R1#traceroute 55.1.1.1 sou 11.1.1.1 numeric
Type escape sequence to abort.
Tracing the route to 55.1.1.1
VRF info: (vrf in name/id, vrf out name/id)
1 12.1.1.2 11 msec 10 msec 11 msec
2 23.1.1.3 21 msec 20 msec 21 msec
3 34.1.1.4 23 msec 22 msec 20 msec
4 45.1.1.5 28 msec * 27 msec