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路由协议迁移 RT1、RT2、RT3上运行EIGRP路由协议，现因业务需要，需要改为运行OSPF路由协议，要求不能影响全网连通性。 拓扑如下： EIGRP配置： RT1 router eigrp 1 network 1.1.1.1 0.0.0.0 network 192.168.1.0 0.0.0.3 network 192.168.1.4 0.0.0.3 no auto-summary eigrp router-id 1.1.1.1 RT2 router eigrp 1 network 2.2.2.2 0.0.0.0 network 192.168.1.0 0.0.0.3 noauto-summary eigrp router-id 2.2.2.2 RT3 router eigrp 1 network 3.3.3.3 0.0.0.0 network 192.168.1.4 0.0.0.3 noauto-summary eigrp router-id 3.3.3.3 查看EIGRP邻居： RT1#showip eigrp neighbors IP-EIGRPneighbors for process 1 H Address Interface Hold Uptime SRTT RTO Q Seq (sec) (ms) Cnt Num 1 192.168.1.6 Se0/1 12 00:05:09 125 750 0 18 0 192.168.1.2 Se0/0 13 00:05:29 63 378 0 20
在RT1、RT2、RT3上查看路由表： RT1#showip route 1.0.0.0/32 is subnetted, 1 subnets C 1.1.1.1 is directly connected, Loopback0 2.0.0.0/32 is subnetted, 1 subnets D 2.2.2.2[90/2297856] via 192.168.1.2, 00:13:53, Serial0/0 3.0.0.0/32 is subnetted,1 subnets D 3.3.3.3[90/2297856] via 192.168.1.6, 00:13:38, Serial0/1 192.168.1.0/30 issubnetted, 2 subnets C 192.168.1.0 is directly connected,Serial0/0 C 192.168.1.4 is directly connected,Serial0/1 RT2# showip route 1.0.0.0/32 is subnetted, 1 subnets D 1.1.1.1[90/2297856] via 192.168.1.1, 00:13:29, Serial0/0 2.0.0.0/32 is subnetted, 1 subnets C 2.2.2.2 is directly connected, Loopback0 3.0.0.0/32 issubnetted, 1 subnets D 3.3.3.3[90/2809856] via 192.168.1.1, 00:13:46, Serial0/0 192.168.1.0/30 is subnetted, 2 subnets C 192.168.1.0 is directly connected,Serial0/0 D 192.168.1.4[90/2681856] via 192.168.1.1, 00:21:54, Serial0/0 RT3#showip route 1.0.0.0/32 issubnetted, 1 subnets D 1.1.1.1[90/2297856] via 192.168.1.5, 00:13:36, Serial0/0 2.0.0.0/32 is subnetted, 1 subnets D 2.2.2.2[90/2809856] via 192.168.1.5, 00:14:08, Serial0/0 3.0.0.0/32 is subnetted, 1 subnets C 3.3.3.3 is directly connected, Loopback0 192.168.1.0/30 is subnetted, 2 subnets D 192.168.1.0[90/2681856] via 192.168.1.5, 00:19:16, Serial0/0 C 192.168.1.4 is directly connected,Serial0/0
此时都为D的路由，即EIGRP的路由。 配上OSPF路由进程： RT1 router ospf 1 router-id 1.1.1.1 log-adjacency-changes network 1.1.1.1 0.0.0.0 area 0 network 192.168.1.0 0.0.0.3 area 0 network 192.168.1.4 0.0.0.3 area 0 RT2 router ospf 1 router-id 2.2.2.2 log-adjacency-changes network 2.2.2.2 0.0.0.0 area 0 network 192.168.1.0 0.0.0.3 area 0 RT3 router ospf 1 router-id 3.3.3.3 log-adjacency-changes network 3.3.3.3 0.0.0.0 area 0 network 192.168.1.4 0.0.0.3 area 0 可以看到OSPF邻居： RT1#showip ospf neighbor NeighborID Pri State Dead Time Address Interface 3.3.3.3 0 FULL/ - 00:00:32 192.168.1.6 Serial0/1 2.2.2.2 0 FULL/ - 00:00:29 192.168.1.2 Serial0/0
OSPF的邻居状态为FULL，链路状态信息也完成同步。 但路由表不会发生变化： RT2# showip route 1.0.0.0/32 issubnetted, 1 subnets D 1.1.1.1[90/2297856] via 192.168.1.1, 00:13:29, Serial0/0 2.0.0.0/32 is subnetted, 1 subnets C 2.2.2.2 is directly connected, Loopback0 3.0.0.0/32 issubnetted, 1 subnets D 3.3.3.3[90/2809856] via 192.168.1.1, 00:13:46, Serial0/0 192.168.1.0/30 is subnetted, 2 subnets C 192.168.1.0 is directly connected,Serial0/0 D 192.168.1.4[90/2681856] via 192.168.1.1, 00:21:54, Serial0/0
因为OSPF的AD值（110）大于EIGRP内部AD值（90），根据路由选择原则，在路由表中无法看到OSPF的路由。 路由协议迁移的方法：可将EIGRP的AD值改大且大于OSPF的AD值，即可使OSPF的路由出现在全局路由表中。 修改EIGRP的AD值： RT1、RT2、RT3： router eigrp 1 distance eigrp 130 200 在修改的过程中，查看RT3的路由表。 RT3#showip route D 1.1.1.1[90/2297856] via 192.168.1.5, 00:00:05, Serial0/0 2.0.0.0/32 is subnetted, 1 subnets O 2.2.2.2 [110/129] via 192.168.1.5,00:00:09, Serial0/0 3.0.0.0/32 is subnetted, 1 subnets C 3.3.3.3 is directly connected, Loopback0 192.168.1.0/30 is subnetted, 2 subnets D 192.168.1.0[90/2681856] via 192.168.1.5, 00:00:05, Serial0/0 C 192.168.1.4 is directly connected,Serial0/0
在RT3上可以看到D和O的路由，表示路由协议正在进行切换。 一段时间之后，在RT1、RT2、RT3查看路由表： RT1#showip route 1.0.0.0/32 is subnetted, 1 subnets C 1.1.1.1 is directly connected, Loopback0 2.0.0.0/32 issubnetted, 1 subnets O 2.2.2.2[110/65] via 192.168.1.2, 00:00:29, Serial0/0 3.0.0.0/32 issubnetted, 1 subnets O 3.3.3.3[110/65] via 192.168.1.6, 00:00:29, Serial0/1 192.168.1.0/30 is subnetted, 2 subnets C 192.168.1.0 is directly connected,Serial0/0 C 192.168.1.4 is directly connected, Serial0/1 RT2#showip route 1.0.0.0/32 is subnetted, 1 subnets O 1.1.1.1[110/65] via 192.168.1.1, 00:00:20, Serial0/0 2.0.0.0/32 is subnetted, 1 subnets C 2.2.2.2 is directly connected, Loopback0 3.0.0.0/32 is subnetted, 1 subnets O 3.3.3.3[110/129] via 192.168.1.1, 00:00:36, Serial0/0 192.168.1.0/30 is subnetted, 2 subnets C 192.168.1.0 is directly connected,Serial0/0 O 192.168.1.4[110/128] via 192.168.1.1, 00:00:20, Serial0/0 RT3#showip route 1.0.0.0/32 is subnetted, 1 subnets O 1.1.1.1[110/65] via 192.168.1.5, 00:00:11, Serial0/0 2.0.0.0/32 is subnetted, 1 subnets O 2.2.2.2[110/129] via 192.168.1.5, 00:00:43, Serial0/0 3.0.0.0/32 is subnetted, 1 subnets C 3.3.3.3 is directly connected, Loopback0 192.168.1.0/30 is subnetted, 2 subnets O 192.168.1.0[110/128] via 192.168.1.5, 00:00:11, Serial0/0 C 192.168.1.4 is directly connected,Serial0/0
路由表中只有O的路由，表示路由协议已经切换完成。此过程中并没有影响全网连通性，因为D和O路由都有自己本身的路由表，进入全局路由表是根据路由选择条件来进入的。 在RT1、RT2、RT3将EIGRP的进程删除： 配置 no router eigrp 1 在RT1上看到如下信息： RT1(config)#norouter eigrp 1 *Mar 1 00:49:58.011: %DUAL-5-NBRCHANGE:IP-EIGRP(0) 1: Neighbor 192.168.1.2 (Serial0/0) is down: interface down *Mar 1 00:49:58.051: %DUAL-5-NBRCHANGE:IP-EIGRP(0) 1: Neighbor 192.168.1.6 (Serial0/1) is down: interface down
显示EIGRP的邻居down。查看邻居，显示为空： RT1#showip eigrp neighbors
再查看路由表，路由表正常： RT1#showip route 1.0.0.0/32 is subnetted, 1 subnets C 1.1.1.1 is directly connected, Loopback0 2.0.0.0/32 is subnetted, 1 subnets O 2.2.2.2[110/65] via 192.168.1.2, 00:01:17, Serial0/0 3.0.0.0/32 issubnetted, 1 subnets O 3.3.3.3[110/65] via 192.168.1.6, 00:01:17, Serial0/1 192.168.1.0/30 is subnetted, 2 subnets C 192.168.1.0 is directly connected,Serial0/0 C 192.168.1.4 is directly connected,Serial0/1
删除EIGRP的进程的过程中也不会影响全网的连通性。 完成了路由协议的迁移，由EIGRP迁移到OSPF，并没有影响全网连通性。 总结： 路由协议迁移可通过修改协议的AD值来改变其进入全局路由表的顺序，从而可以删除，来达到路由协议迁移的目的。 在迁移过程中，要等进入全局路由表的路由协议的信息达到同步之后，并且在路由表中学到了所有的路由，才可删除没有进入全局路由表的路由协议的配置。
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发表于 2015-12-15 15:39:24
