1. Experimental requirements
1. Each router of R2-R7 has a loopback interface for establishing neighbors; at the same time, there is also a loopback interface to replace the connection user interface; finally, these interface networks for user connection need to be able to communicate with the loopback interface of R1/8.
2. AS2 network segment address 172.16.0.0/16, reduce the number of routing entries.
2. Experimental topology
3. Experimental process
1. IP address planning
172.16.0.0/16
172.16.0.0/24—backbone link 172.16.0.0/30
172.16.1.0/24—establish neighbor loopback, 172.16.1.1/24, 172.16.1.2/24, 172.16.1.3/24, etc.
172.16 .2.0/24
172.16.3.0/24
172.16.4.0/24
172.16.5.0/24
172.16.6.0/24
172.16.7.0/24
The remaining 6 network segments are used as service network segments of R2-7.
2. Configure the IP address
R1：
[R1]int g0/0/0 [R1-GigabitEthernet0/0/0]ip address 12.1.1.1 24 [R1]int LoopBack 0 [R1-LoopBack0]ip address 1.1.1.1 32R2：
[R2]int g0/0/0 [R2-GigabitEthernet0/0/0]ip address 12.1.1.1 24 [R2-GigabitEthernet0/0/0]int g0/0/1 [R2-GigabitEthernet0/0/1]ip address 172.16.0.1 30 [R2-GigabitEthernet0/0/0]int g0/0/2 [R2-GigabitEthernet0/0/2]ip address 172.16.0.9 30 [R2]int LoopBack 0 [R2-LoopBack0]ip address 172.16.1.2 32R3：
[R3]int g0/0/0 [R3-GigabitEthernet0/0/0]ip address 172.16.0.2 30 [R3-GigabitEthernet0/0/0]int g0/0/1 [R3-GigabitEthernet0/0/1]ip address 172.16.0.5 30 [R3]int LoopBack 0 [R3-LoopBack0]ip address 172.16.1.3 32R4：
[R4]int g0/0/0 [R4-GigabitEthernet0/0/0]ip address 172.16.0.6 30 [R4-GigabitEthernet0/0/0]int g0/0/1 [R4-GigabitEthernet0/0/1]ip address 172.16.0.21 30 [R4]int LoopBack 0 [R4-LoopBack0]ip address 172.16.1.3 32R5:
[R5]int g0/0/0 [R5-GigabitEthernet0/0/0]ip address 172.16.0.13 30 [R5-GigabitEthernet0/0/0]int g0/0/1 [R5-GigabitEthernet0/0/1]ip address 172.16.0.10 30 [R5]int LoopBack 0 [R5-LoopBack0]ip address 172.16.1.5 32R6：
[R6]int g0/0/0 [R6-GigabitEthernet0/0/0]ip address 172.16.0.14 30 [R6-GigabitEthernet0/0/0]int g0/0/1 [R6-GigabitEthernet0/0/1]ip address 172.16.0.17 30 [R6]int LoopBack 0 [R6-LoopBack0]ip address 172.16.1.6 32R7：
[R7]int g0/0/0 [R7-GigabitEthernet0/0/0]ip address 172.16.0.22 30 [R7-GigabitEthernet0/0/0]int g0/0/1 [R7-GigabitEthernet0/0/1]ip address 172.16.0.18 30 [R7-GigabitEthernet0/0/0]int g0/0/2 [R7-GigabitEthernet0/0/1]ip address 78.1.1.1.1 24 [R7]int LoopBack 0 [R7-LoopBack0]ip address 172.16.1.7 32R8：
[R7]int g0/0/0 [R7-GigabitEthernet0/0/0]ip address 78.1.1.2 24 [R7]int LoopBack 0 [R7-LoopBack0]ip address 8.8.8.8 322. Start and declare the IGP protocol in AS2
R2：
[R2]ospf 1 [R2-ospf-1]area 0 [R2-ospf-1-area-0.0.0.0]network 172.16.0.0 0.0.255.255R3：
[R3]ospf 1 [R3-ospf-1]area 0 [R3-ospf-1-area-0.0.0.0]network 172.16.0.0 0.0.255.255R4：
[R4]ospf 1 [R4-ospf-1]area 0 [R4-ospf-1-area-0.0.0.0]network 172.16.0.0 0.0.255.255R5：
[R5]ospf 1 [R5-ospf-1]area 0 [R5-ospf-1-area-0.0.0.0]network 172.16.0.0 0.0.255.255R6：
[R6]ospf 1 [R6-ospf-1]area 0 [R6-ospf-1-area-0.0.0.0]network 172.16.0.0 0.0.255.255R7：
[R7]ospf 1 [R7-ospf-1]area 0 [R7-ospf-1-area-0.0.0.0]network 172.16.0.0 0.0.255.2554. Start the BGP protocol and establish a neighbor relationship
R1：
[R1]bgp 1 [R1-bgp]router-id 1.1.1.1 [R1-bgp]peer 12.1.1.2 as-number 2R2：
[R2]bgp 64512 [R2-bgp]router-id 172.16.1.2 [R2-bgp]confederation id 2 [R2-bgp]peer 12.1.1.1 as-number 1 [R2-bgp]peer 172.16.1.3 as-number 64512 [R2-bgp]peer 172.16.1.3 connect-interface LoopBack 0 [R2-bgp]confederation peer-as 64513 [R2-bgp]peer 172.16.1.5 as-number 64513 [R2-bgp]peer 172.16.1.5 ebgp-max-hop 2 [R2-bgp]peer 172.16.1.5 connect-interface LoopBack 0R3：
[R3]bgp 64512 [R3-bgp]router-id 172.16.1.3 [R3-bgp]peer 172.16.1.2 as-number 64512 [R3-bgp]peer 172.16.1.2 connect-interface LoopBack 0 [R3-bgp]peer 172.16.1.4 as-number 64512 [R3-bgp]peer 172.16.1.4 connect-interface LoopBack 0R4：
[R4]bgp 64512 [R4-bgp]router-id 172.16.1.4 [R4-bgp]confederation id 2 [R4-bgp]peer 172.16.1.3 as-number 64512 [R4-bgp]peer 172.16.1.3 connect-interface LoopBack 0 [R4-bgp]confederation peer-as 64513 [R4-bgp]peer 172.16.1.7 as-number 64513 [R4-bgp]peer 172.16.1.7 ebgp-max-hop 2 [R4-bgp]peer 172.16.1.7 connect-interface LoopBack 0R5：
[R5]bgp 64513 [R5-bgp]router-id 172.16.1.5 [R5-bgp]confederation id 2 [R5-bgp]confederation peer-as 64512 [R5-bgp]peer 172.16.1.2 as-number 64512 [R5-bgp]peer 172.16.1.2 ebgp-max-hop 2 [R5-bgp]peer 172.16.1.2 connect-interface LoopBack 0 [R5-bgp]peer 172.16.1.6 as-number 64513 [R5-bgp]peer 172.16.1.6 connect-interface LoopBack 0R6：
[R6]bgp 64513 [R6-bgp]router-id 172.16.1.6 [R6-bgp]confederation id 2 [R6-bgp]peer 172.16.1.5 as-number 64513 [R6-bgp]peer 172.16.1.5 connect-interface LoopBack 0 [R6-bgp]peer 172.16.1.7 as-number 64513 [R6-bgp]peer 172.16.1.7 connect-interface LoopBack 0R7：
[R7]bgp 64513 [R7-bgp]router-id 172.16.1.7 [R7-bgp]peer 172.16.1.6 as-number 64513 [R7-bgp]peer 172.16.1.6 connect-interface LoopBack 0 [R7-bgp]confederation peer-as 64512 [R7-bgp]peer 172.16.1.4 as-number 64512 [R7-bgp]peer 172.16.1.4 ebgp-max-hop 2 [R7-bgp]peer 172.16.1.4 connect-interface LoopBack 0 [R7-bgp]peer 78.1.1.8 as-number 3
R8：[R8]bgp 3 [R8-bgp]router-id 8.8.8.8 [R8-bgp]peer 78.1.1.7 as-number 25. Announce business network segment
R1：
[R1-bgp]network 10.1.1.0 24Check the BGP table on R2 and find that the service network segment learned on R1 is optimal, but the ones learned on R3 and R5 are not optimal, so the next-hop IP address needs to be modified;
R2：
[R2-bgp]peer 172.16.1.3 next-hop-local [R2-bgp]peer 172.16.1.5 next-hop-localWrite reflectors on R3 and R6
R3：
[R3-bgp]peer 172.16.1.4 reflect-clientR6：
[R6-bgp]peer 172.16.1.7 reflect-clientAnnounce the service network segment of R8 and modify the next hop on R7
R8：
[R8-bgp]network 10.1.8.0 24R7：
[R7-bgp]peer 172.16.1.4 next-hop-local [R7-bgp]peer 172.16.1.6 next-hop-localAnnounce the aggregated user interface network on R2 and R7
R2：
[R2]ip route-static 172.16.0.0 21 NULL 0 [R2]bgp 64512 [R2-bgp]network 172.16.0.0 21R7：
[R7]ip route-static 172.16.0.0 21 NULL 0 [R7]bgp 64513 [R7-bgp]network 172.16.0.0 21
4. Experimental results
