将ospf与rip相互引入。

由于华为的ospf内部路由优先级为10，外部引入路由优先级为150 。

RIP的优先级为100。

所以RIP的路由优先级比ospf的外部引入的小，故RIP路由优先于ospf外部路由。

刚构建的拓扑，并不存在环路和次优路径，当ar2上的接口出现down的现象后，才会出现次优路径或者环路现象<ar4>disp ip routing-tableRoute Flags: R - relay, D - download to fib------------------------------------------------------------------------------Routing Tables: PublicDestinations : 18 Routes : 18Destination/Mask Proto Pre Cost Flags NextHop Interface10.1.12.0/24 OSPF 10 2 D 10.1.24.2 GigabitEthernet0/0/010.1.23.0/24 OSPF 10 2 D 10.1.24.2 GigabitEthernet0/0/010.1.24.0/24 Direct 0 0 D 10.1.24.4 GigabitEthernet0/0/010.1.24.4/32 Direct 0 0 D 127.0.0.1 GigabitEthernet0/0/010.1.24.255/32 Direct 0 0 D 127.0.0.1 GigabitEthernet0/0/022.1.1.1/32 OSPF 10 1 D 10.1.24.2 GigabitEthernet0/0/033.1.1.1/32 OSPF 10 2 D 10.1.24.2 GigabitEthernet0/0/044.1.1.1/32 Direct 0 0 D 127.0.0.1 LoopBack0127.0.0.0/8 Direct 0 0 D 127.0.0.1 InLoopBack0127.0.0.1/32 Direct 0 0 D 127.0.0.1 InLoopBack0127.255.255.255/32 Direct 0 0 D 127.0.0.1 InLoopBack0172.16.0.0/24 O_ASE 150 1 D 10.1.24.2 GigabitEthernet0/0/0 172.16.2.0/24 O_ASE 150 1 D 10.1.24.2 GigabitEthernet0/0/0192.168.35.0/24 O_ASE 150 1 D 10.1.24.2 GigabitEthernet0/0/0192.168.45.0/24 Direct 0 0 D 192.168.45.4 GigabitEthernet0/0/1192.168.45.4/32 Direct 0 0 D 127.0.0.1 GigabitEthernet0/0/1192.168.45.255/32 Direct 0 0 D 127.0.0.1 GigabitEthernet0/0/1255.255.255.255/32 Direct 0 0 D 127.0.0.1 InLoopBack0<ar4>[ar3]disp ip routing-tableRoute Flags: R - relay, D - download to fib------------------------------------------------------------------------------Routing Tables: PublicDestinations : 18 Routes : 18Destination/Mask Proto Pre Cost Flags NextHop Interface10.1.12.0/24 OSPF 10 2 D 10.1.23.2 GigabitEthernet0/0/010.1.23.0/24 Direct 0 0 D 10.1.23.3 GigabitEthernet0/0/010.1.23.3/32 Direct 0 0 D 127.0.0.1 GigabitEthernet0/0/010.1.23.255/32 Direct 0 0 D 127.0.0.1 GigabitEthernet0/0/010.1.24.0/24 OSPF 10 2 D 10.1.23.2 GigabitEthernet0/0/022.1.1.1/32 OSPF 10 1 D 10.1.23.2 GigabitEthernet0/0/033.1.1.1/32 Direct 0 0 D 127.0.0.1 LoopBack044.1.1.1/32 OSPF 10 2 D 10.1.23.2 GigabitEthernet0/0/0127.0.0.0/8 Direct 0 0 D 127.0.0.1 InLoopBack0127.0.0.1/32 Direct 0 0 D 127.0.0.1 InLoopBack0127.255.255.255/32 Direct 0 0 D 127.0.0.1 InLoopBack0172.16.0.0/24 O_ASE 150 1 D 10.1.23.2 GigabitEthernet0/0/0172.16.2.0/24 O_ASE 150 1 D 10.1.23.2 GigabitEthernet0/0/0192.168.35.0/24 Direct 0 0 D 192.168.35.3 GigabitEthernet0/0/1192.168.35.3/32 Direct 0 0 D 127.0.0.1 GigabitEthernet0/0/1192.168.35.255/32 Direct 0 0 D 127.0.0.1 GigabitEthernet0/0/1192.168.45.0/24 O_ASE 150 1 D 10.1.23.2 GigabitEthernet0/0/0255.255.255.255/32 Direct 0 0 D 127.0.0.1 InLoopBack0当ar3与ar2的邻居状态出现震荡后ar3收到172.16.0.0/24和172.16.2.0/24的路由会由于ospf的震荡导致邻居关系重新建立，LSA重新交互。

同时由于RIP并没有断开，同时因为rip的路由优先级比ospf的外部路由要低，所以ar3的172.16.0.0/24和172.16.2.0/24两个路由浮现的协议为RIP。

导致次优路径的产生。

Ar4因为没有产生震荡所以路由表没有改变。

Ar4和ar2之间链路状态出现变化同样道理。

<ar3>disp ip routing-tableRoute Flags: R - relay, D - download to fib------------------------------------------------------------------------------Routing Tables: PublicDestinations : 22 Routes : 22Destination/Mask Proto Pre Cost Flags NextHop Interface10.1.12.0/24 OSPF 10 2 D 10.1.23.2 GigabitEthernet0/0/010.1.23.0/24 Direct 0 0 D 10.1.23.3 GigabitEthernet0/0/010.1.23.3/32 Direct 0 0 D 127.0.0.1 GigabitEthernet0/0/010.1.23.255/32 Direct 0 0 D 127.0.0.1 GigabitEthernet0/0/010.1.24.0/24 OSPF 10 2 D 10.1.23.2 GigabitEthernet0/0/022.1.1.1/32 OSPF 10 1 D 10.1.23.2 GigabitEthernet0/0/033.1.1.1/32 Direct 0 0 D 127.0.0.1 LoopBack044.1.1.1/32 OSPF 10 2 D 10.1.23.2 GigabitEthernet0/0/055.1.1.1/32 RIP 100 1 D 192.168.35.5 GigabitEthernet0/0/1127.0.0.0/8 Direct 0 0 D 127.0.0.1 InLoopBack0127.0.0.1/32 Direct 0 0 D 127.0.0.1 InLoopBack0127.255.255.255/32 Direct 0 0 D 127.0.0.1 InLoopBack0172.16.0.0/24 RIP 100 2 D 192.168.35.5 GigabitEthernet0/0/1 172.16.2.0/24 RIP 100 2 D 192.168.35.5 GigabitEthernet0/0/1 192.168.35.0/24 Direct 0 0 D 192.168.35.3 GigabitEthernet0/0/1 192.168.35.3/32 Direct 0 0 D 127.0.0.1 GigabitEthernet0/0/1 192.168.35.255/32 Direct 0 0 D 127.0.0.1 GigabitEthernet0/0/1 192.168.45.0/24 RIP 100 1 D 192.168.35.5 GigabitEthernet0/0/1 255.255.255.255/32 Direct 0 0 D 127.0.0.1 InLoopBack0<ar4>disp ip routing-tableRoute Flags: R - relay, D - download to fib------------------------------------------------------------------------------Routing Tables: PublicDestinations : 22 Routes : 22Destination/Mask Proto Pre Cost Flags NextHop Interface10.1.12.0/24 OSPF 10 2 D 10.1.24.2 GigabitEthernet0/0/010.1.23.0/24 OSPF 10 2 D 10.1.24.2 GigabitEthernet0/0/010.1.24.0/24 Direct 0 0 D 10.1.24.4 GigabitEthernet0/0/010.1.24.4/32 Direct 0 0 D 127.0.0.1 GigabitEthernet0/0/010.1.24.255/32 Direct 0 0 D 127.0.0.1 GigabitEthernet0/0/022.1.1.1/32 OSPF 10 1 D 10.1.24.2 GigabitEthernet0/0/033.1.1.1/32 OSPF 10 2 D 10.1.24.2 GigabitEthernet0/0/044.1.1.1/32 Direct 0 0 D 127.0.0.1 LoopBack055.1.1.1/32 RIP 100 1 D 192.168.45.5 GigabitEthernet0/0/1127.0.0.0/8 Direct 0 0 D 127.0.0.1 InLoopBack0127.0.0.1/32 Direct 0 0 D 127.0.0.1 InLoopBack0127.255.255.255/32 Direct 0 0 D 127.0.0.1 InLoopBack0 172.16.0.0/24 O_ASE 150 1 D 10.1.24.2 GigabitEthernet0/0/0 172.16.2.0/24 O_ASE 150 1 D 10.1.24.2 GigabitEthernet0/0/0 192.168.35.0/24 RIP 100 1 D 192.168.45.5 GigabitEthernet0/0/1 192.168.45.0/24 Direct 0 0 D 192.168.45.4 GigabitEthernet0/0/1 192.168.45.4/32 Direct 0 0 D 127.0.0.1 GigabitEthernet0/0/1 192.168.45.255/32 Direct 0 0 D 127.0.0.1 GigabitEthernet0/0/1 255.255.255.255/32 Direct 0 0 D 127.0.0.1 InLoopBack0[ar2-GigabitEthernet0/0/0]disp ip routing-tableRoute Flags: R - relay, D - download to fib------------------------------------------------------------------------------Routing Tables: PublicDestinations : 27 Routes : 31Destination/Mask Proto Pre Cost Flags NextHop Interface10.0.0.0/24 O_ASE 150 1 D 10.1.24.4 GigabitEthernet2/0/010.0.1.0/24 O_ASE 150 1 D 10.1.24.4 GigabitEthernet2/0/010.0.2.0/24 O_ASE 150 1 D 10.1.23.3 GigabitEthernet0/0/1O_ASE 150 1 D 10.1.24.4 GigabitEthernet2/0/010.1.12.0/24 Direct 0 0 D 10.1.12.2 GigabitEthernet0/0/010.1.12.2/32 Direct 0 0 D 127.0.0.1 GigabitEthernet0/0/010.1.12.255/32 Direct 0 0 D 127.0.0.1 GigabitEthernet0/0/010.1.23.0/24 Direct 0 0 D 10.1.23.2 GigabitEthernet0/0/110.1.23.2/32 Direct 0 0 D 127.0.0.1 GigabitEthernet0/0/110.1.23.255/32 Direct 0 0 D 127.0.0.1 GigabitEthernet0/0/110.1.24.0/24 Direct 0 0 D 10.1.24.2 GigabitEthernet2/0/010.1.24.2/32 Direct 0 0 D 127.0.0.1 GigabitEthernet2/0/010.1.24.255/32 Direct 0 0 D 127.0.0.1 GigabitEthernet2/0/022.1.1.1/32 Direct 0 0 D 127.0.0.1 LoopBack033.1.1.1/32 OSPF 10 1 D 10.1.23.3 GigabitEthernet0/0/144.1.1.1/32 OSPF 10 1 D 10.1.24.4 GigabitEthernet2/0/055.1.1.1/32 O_ASE 150 1 D 10.1.24.4 GigabitEthernet2/0/0O_ASE 150 1 D 10.1.23.3 GigabitEthernet0/0/1 127.0.0.0/8 Direct 0 0 D 127.0.0.1 InLoopBack0127.0.0.1/32 Direct 0 0 D 127.0.0.1 InLoopBack0127.255.255.255/32 Direct 0 0 D 127.0.0.1 InLoopBack0172.16.0.0/24 Static 60 0 RD 10.1.12.1 GigabitEthernet0/0/0 172.16.1.0/24 Static 60 0 RD 10.1.12.1 GigabitEthernet0/0/0 172.16.2.0/24 Static 60 0 RD 10.1.12.1 GigabitEthernet0/0/0 172.16.3.0/24 Static 60 0 RD 10.1.12.1 GigabitEthernet0/0/0172.16.4.0/24 Static 60 0 RD 10.1.12.1 GigabitEthernet0/0/0 192.168.35.0/24 O_ASE 150 1 D 10.1.24.4 GigabitEthernet2/0/0O_ASE 150 1 D 10.1.23.3 GigabitEthernet0/0/1 192.168.45.0/24 O_ASE 150 1 D 10.1.24.4 GigabitEthernet2/0/0O_ASE 150 1 D 10.1.23.3 GigabitEthernet0/0/1 255.255.255.255/32 Direct 0 0 D 127.0.0.1 InLoopBack0追踪路径：[ar4]tracert 172.16.0.1traceroute to 172.16.0.1(172.16.0.1), max hops: 30 ,packet length: 40,press CTRL_C to break1 10.1.24.2 20 ms 20 ms 10 ms2 10.1.12.1 30 ms 30 ms 20 ms<ar3>tracert 172.16.0.1traceroute to 172.16.0.1(172.16.0.1), max hops: 30 ,packet length: 40,press CTRL_C to break1 192.168.35.5 40 ms 10 ms 10 ms2 * 192.168.45.4 40 ms 40 ms3 10.1.24.2 20 ms 20 ms 20 ms4 10.1.12.1 20 ms 30 ms 30 ms环路现象，ar1和ar2之间的链路断链后。