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1.进行地址划分

172.16.2.0 /24——R2

172.16.3.0 /24——R3

172.16.4.0 /24——R4

172.16.5.0 /24——R5

172.16.6.0 /24——R6

172.16.7.0 /24——R7

172.16.1.0 /24——MA骨干网络

172.16.1.0 /29——R2-R3

172.16.1.8 /29——R3-R4

172.16.1.16 /29——R2-R5

172.16.1.24 /29——R5-R6

172.16.1.32 /29——R6-R7

172.16.1.40 /29——R4-R7

2.配置各个路由器的接口ip
以r2为例

 [r2]int g 0/0/0

[r2-GigabitEthernet0/0/0]ip ad 12.0.0.2 24

[r2-GigabitEthernet0/0/0]q

[r2]int g0/0/1

[r2-GigabitEthernet0/0/1]ip ad 172.16.1.1 29

[r2-GigabitEthernet0/0/1]q

[r2]int g0/0/2

[r2-GigabitEthernet0/0/2]ip ad 172.16.1.17 29

[r2]int l0

[r2-LoopBack0]ip ad 172.16.2.1 24

[r2-LoopBack0]
                                          

3.在AS2内部启动ospf协议
以r2为例

[r2]ospf 1 router-id 2.2.2.2

[r2-ospf-1]a 0

[r2-ospf-1-area-0.0.0.0]network 172.16.0.0 0.0.255.255

查看AS2内部联通情况

3.启动BGP
建立 BGP 邻居关系，R1 和 R 2、R7和R8 为EBGP邻居关系，若使用环回建邻，则需要修改TTL值（BGP邻居关系间数据包TTL值为1）。AS2 中 R2 和 R5、R4和R7为EBGP关系，在建邻时，需要声明所在大AS号和大AS内部邻居的小AS号，其他设备之间为IBGP邻居关系。

[r1]bgp 1

[r1-bgp]router-id 1.1.1.1

[r1-bgp]peer 12.0.0.2 as-number 2

[r2]bgp 64512                              

[r2-bgp]router-id 2.2.2.2                          

[r2-bgp]confederation id 2                       

[r2-bgp]confederation peer-as 64513                                  
                                                                  
[[r2-bgp]peer 12.0.0.1 as 1      

[r2-bgp]peer 172.16.3.1 as-number 64512

[r2-bgp]peer 172.16.3.1 connect-interface LoopBack 0

[r2-bgp]peer 172.16.5.1 as-number 64513   

[r2-bgp]peer 172.16.5.1 connect-interface LoopBack 0

[r2-bgp]peer 172.16.5.1 ebgp-max-hop 2    

[r3]bgp 64512

[r3-bgp]router-id 3.3.3.3

[r3-bgp]confederation id 2

[r3-bgp]peer 172.16.2.1 as 64512           

[r3-bgp]peer 172.16.2.1 connect-interface LoopBack 0

[r3-bgp]peer 172.16.4.1 as 64512          

[r3-bgp]peer 172.16.4.1 connect-interface LoopBack 0

[r4]bgp 64512

[r4-bgp]router-id 4.4.4.4

[r4-bgp]confederation id 2

[r4-bgp]confederation peer-as 64513

[r4-bgp]peer 172.16.3.1 advertise-community

[r4-bgp]peer 172.16.3.1 as 64512

[r4-bgp]peer 172.16.3.1 connect-interface LoopBack 0

[r4-bgp]peer 172.16.7.1 as 64513

[r4-bgp]peer 172.16.7.1 connect-interface LoopBack 0

[r4-bgp]peer 172.16.7.1 ebgp-max-hop 2

[r5]bgp 64513

[r5-bgp]router-id 5.5.5.5

[r5-bgp]confederation id 2

[r5-bgp]confederation peer-as 64512

[r5-bgp]peer 172.16.2.1 as 64512

[r5-bgp]peer 172.16.2.1 connect-interface LoopBack 0

[r5-bgp]peer 172.16.2.1 ebgp-max-hop 2        

[r5-bgp]peer 172.16.6.1 as 64513

[r5-bgp]peer 172.16.6.1 connect-interface LoopBack 0

[r6]bgp 64513

[r6-bgp]router-id 6.6.6.6

[r6-bgp]confederation id  2

[r6-bgp]peer 172.16.5.1 as-number 64513

[r6-bgp]peer 172.16.5.1 connect-interface LoopBack 0

[r6-bgp]peer 172.16.7.1 as 64513

[r6-bgp]peer 172.16.7.1 connect-interface LoopBack 0

[r7]bgp 64513

[r7-bgp]router-id 7.7.7.7

[r7-bgp]confederation  id 2

[r7-bgp]confederation  peer-as  64512

[r7-bgp]peer 172.16.6.1 as 64513

[r7-bgp]peer  172.16.6.1 connect-interface LoopBack 0

[r7-bgp]peer 172.16.4.1 as 64512

[r7-bgp]peer 172.16.4.1 connect-interface LoopBack 0

[r7-bgp]peer 172.16.4.1 ebgp-max-hop 2

[r7-bgp]peer 78.0.0.2 as 3

[r8]bgp 3

[r8-bgp]router-id 8.8.8.8

[r8-bgp]peer 78.0.0.1 as 2

r2bgp

r7bgp

宣告路由

[r1]bgp 1

[r1-bgp]network 10.0.0.1 24

r2和r8操作相同
[r2]bgp 64512

[r2-bgp]peer 172.16.3.1 next-hop-local

[r2-bgp]peer 172.16.5.1 next-hop-local

[r3-bgp]peer 172.16.2.1 reflect-client 
R2为客户端   

[r6]bgp 64513

[r6-bgp]peer 172.16.7.1 reflect-client 
R7为客户端

[r7]bgp 64513

[r7-bgp]peer 172.16.4.1 next-hop-local

[r7-bgp]peer 172.16.6.1 next-hop-local

减少路由条目，路由汇总

[r2]ip route-static 172.16.0.0 21 NULL 0

[r7]ip route-static 172.16.0.0 21 NULL 0

[r7]bgp 64513

[r7-bgp]network 172.16.0.0 21

使用隧道接口避免192.168.2.0/24被宣告

r1]int t 0/0/0

[r1-Tunnel0/0/0]ip ad 99.0.0.1 24

[r1-Tunnel0/0/0]tunnel-protocol gre         

[r1-Tunnel0/0/0]source 10.0.0.1

[r1-Tunnel0/0/0]destination 11.0.0.1

[r1-Tunnel0/0/0]q

[r1]ip route-static 192.168.2.0 24 99.0.0.2
---------------------------------------------
[r8]int t0/0/0

[r8-Tunnel0/0/0] ip ad 99.0.0.2 24

[r8-Tunnel0/0/0]tunnel-protocol gre         

[r8-Tunnel0/0/0]source 11.0.0.1

[r8-Tunnel0/0/0]destination 10.0.0.1

[r8-Tunnel0/0/0]q        

[r8]ip route-static 192.168.1.0 24 99.0.0.1

实验结果
R1

R2