1） 底层的基本配置：
R1#sh ip int b
Interface IP-Address OK? Method Status Protocol
Serial2/1 12.0.0.1 YES manual up up
Loopback0 1.1.1.1 YES manual up up
R2#sh ip int b
Interface IP-Address OK? Method Status Protocol
Serial2/1 12.0.0.2 YES manual up up
Serial2/2 23.0.0.2 YES manual up up
Loopback0 2.2.2.2 YES manual up up
R3#sh ip int b
Interface IP-Address OK? Method Status Protocol
Serial2/1 23.0.0.3 YES manual up up
Serial2/2 34.0.0.3 YES manual up up
R4#sh ip int b
Interface IP-Address OK? Method Status Protocol
Serial2/1 34.0.0.4 YES manual up up
Serial2/2 45.0.0.4 YES manual up up
Loopback0 4.4.4.4 YES manual up up
R5#sh ip int b
Interface IP-Address OK? Method Status Protocol
Serial2/2 45.0.0.5 YES manual up up
Loopback0 5.5.5.5 YES manual up up
2） R1和R2建立EBGP邻居关系并传递路由：
R1(config)#router bgp 100
R1(config-router)#neighbor 12.0.0.2 remote-as 200
R2(config)#router bgp 200
R2(config-router)#neighbor 12.0.0.1 remote-as 100
查看邻居关系：
R1#sh ip bgp summary
Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
12.0.0.2 4 200 6 6 1 0 0 00:02:07 0
R1#
R2#sh ip bgp su
R2#sh ip bgp summary
BGP router identifier 2.2.2.2, 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
12.0.0.1 4 100 4 4 1 0 0 00:00:02 0
\\ R1和R2的邻居关系建立起来\\
R1#sh ip rou
1.0.0.0/24 is subnetted, 1 subnets
C 1.1.1.0 is directly connected, Loopback0
12.0.0.0/24 is subnetted, 1 subnets
C 12.0.0.0 is directly connected, Serial2/1
R2#sh ip rou
2.0.0.0/24 is subnetted, 1 subnets
C 2.2.2.0 is directly connected, Loopback0
23.0.0.0/24 is subnetted, 1 subnets
C 23.0.0.0 is directly connected, Serial2/2
12.0.0.0/24 is subnetted, 1 subnets
C 12.0.0.0 is directly connected, Serial2/1
可见建立邻居但R2没学习到R1的路由
在R1上手动汇总1.1.1.0网段路由：
R1(config)#router bgp 100
R1(config-router)#network 1.1.1.0 mask 255.255.255.0
查看R1和R2 的bgp：
R1#sh ip bgp
BGP table version is 2, local router ID is 1.1.1.1
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
r RIB-failure, S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
*> 1.1.1.0/24 0.0.0.0 0 32768 i
可见1.1.1.0网段被优化且下一跳为0.0.0.0及下一跳为自己（可达）
R2#sh ip bgp
BGP table version is 2, local router ID is 2.2.2.2
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
r RIB-failure, S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
*> 1.1.1.0/24 12.0.0.1 0 0 100 i
可见1.1.1.0网段被优化且下一跳为12.0.0.1（可达）
R2#sh ip rou
1.0.0.0/24 is subnetted, 1 subnets
B 1.1.1.0 [20/0] via 12.0.0.1, 00:06:27
2.0.0.0/24 is subnetted, 1 subnets
C 2.2.2.0 is directly connected, Loopback0
23.0.0.0/24 is subnetted, 1 subnets
C 23.0.0.0 is directly connected, Serial2/2
12.0.0.0/24 is subnetted, 1 subnets
C 12.0.0.0 is directly connected, Serial2/1
可见R2学习到1.1.1.0的网段
3） R2.R3,R4之间跑eigrp并关闭自动汇总：
R2(config)#router eigrp 10
R2(config-router)#network 23.0.0.0
R2(config-router)#net 2.2.2.0
R2(config-router)#no auto-summary
R3(config)#router eigrp 10
R3(config-router)#net 23.0.0.0
R3(config-router)#net 34.0.0.0
R3(config-router)#no auto-summary
R4(config)#router eigrp 10
R4(config-router)#net 34.0.0.0
R4(config-router)#net 4.4.4.0
R4(config-router)#no auto-summary
R2#ping 4.4.4.4
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 4.4.4.4, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 48/88/152 ms
确保R2能ping通4.4.4.4
R2和R4之间建立IBGP | 
