OSPF虚链路（virtual-link）配置实例这个配置将验证一个OSPF虚电路（Virtual-Link）的过程，重点在观察虚链路连接的临时网络与正常区域间路由有何区别。

上图中区域4（area 4）没有和area 0直接相连。

在R2与R3之间配置了一条虚链路。

// R1 //int lo0ip ad 1.1.1.1 255.255.255.0int e0ip ad 192.1.1.1 255.255.255.0router os 1network 192.1.1.0 0.0.0.255 area 0// R2 //int lo0ip ad 2.2.2.2 255.255.255.0int e0ip ad 192.1.1.2 255.255.255.0int e1ip ad 193.1.1.2 255.255.255.0router os 1network 192.1.1.0 0.0.0.255 area 0network 193.1.1.0 0.0.0.255 area 1// R3 //int lo0ip ad 3.3.3.3 255.255.255.0int e1ip ad 193.1.1.3 255.255.255.0int e0ip ad 194.1.1.3 255.255.255.0router os 1network 193.1.1.0 0.0.0.255 area 1network 194.1.1.0 0.0.0.255 area 4// R4 //int lo0ip ad 4.4.4.4 255.255.255.0int e0ip ad 194.1.1.4 255.255.255.0router os 1network 194.1.1.0 0.0.0.255 area 4基本配置完成后，我们在每台路由器上分别来验证一下：r1#sh ip os neiTime Address Interface2.2.2.2 1 FULL/BDR 00:00:33 192.1.1.2 Eth ernet0/0r1#r1#sh ip ro1.0.0.0/24 is subnetted, 1 subnetsC 1.1.1.0 is directly connected, Loopback0O IA 193.1.1.0/24 [110/20] via 192.1.1.2, 00:00:19, Ethernet0/0C 192.1.1.0/24 is directly connected, Ethernet0/0//注意R1上有关于193.1.1.0的路由条目，是属于IA类型（域间路由）r2#sh ip os neiNeighbor ID Pri State DeadTime Address Interface1.1.1.1 1 FULL/DR 00:00:35 192.1.1.1 Eth ernet0/03.3.3.3 1 FULL/BDR 00:00:35 193.1.1.3 Eth ernet1/0r2#r2#r2#sh ip ro2.0.0.0/24 is subnetted, 1 subnetsC 2.2.2.0 is directly connected, Loopback0C 193.1.1.0/24 is directly connected, Ethernet1/0C 192.1.1.0/24 is directly connected, Ethernet0/0r3#sh ip os neiNeighbor ID Pri State DeadTime Address Interface2.2.2.2 1 FULL/DR 00:00:32 193.1.1.2 Eth ernet1/04.4.4.4 1 FULL/DR 00:00:34 194.1.1.4 Eth ernet0/0r3#sh ip ro3.0.0.0/24 is subnetted, 1 subnetsC 3.3.3.0 is directly connected, Loopback0C 193.1.1.0/24 is directly connected, Ethernet1/0O IA 192.1.1.0/24 [110/20] via 193.1.1.2, 00:02:49, Ethernet1/0C 194.1.1.0/24 is directly connected, Ethernet0/0//注意R3中有关于192.1.1.0的路由是属于IA类型（域间路由）r4#sh ip os neiTime Address Interface3.3.3.3 1 FULL/BDR 00:00:33 194.1.1.3 Eth ernet0/0r4#sh ip ro4.0.0.0/24 is subnetted, 1 subnetsC 4.4.4.0 is directly connected, Loopback0C 194.1.1.0/24 is directly connected, Ethernet0/0//R4上没有关于AREA 0内的任何路由信息我们下面在R2、R3上添加Virtual-link的配置：R2：router os 1area 1 virtual-link 3.3.3.3R3:router os 1area 1 virtual-link 2.2.2.2对比之前的路由信息，看有何区别：r1#sh ip ro1.0.0.0/24 is subnetted, 1 subnetsC 1.1.1.0 is directly connected, Loopback0O IA 193.1.1.0/24 [110/20] via 192.1.1.2, 00:00:01, Ethernet0/0C 192.1.1.0/24 is directly connected, Ethernet0/0O IA 194.1.1.0/24 [110/30] via 192.1.1.2, 00:00:01, Ethernet0/0//多了一条194网段的路由，类型IA（区域间）r2#sh ip ro2.0.0.0/24 is subnetted, 1 subnetsC 2.2.2.0 is directly connected, Loopback0C 193.1.1.0/24 is directly connected, Ethernet1/0C 192.1.1.0/24 is directly connected, Ethernet0/0O IA 194.1.1.0/24 [110/20] via 193.1.1.3, 00:00:06, Ethernet1/0//多了一条194网段路由，类型为IA（区域间）r3#sh ip ro3.0.0.0/24 is subnetted, 1 subnetsC 3.3.3.0 is directly connected, Loopback0C 193.1.1.0/24 is directly connected, Ethernet1/0O 192.1.1.0/24 [110/20] via 193.1.1.2, 00:02:56, Ethernet1/0C 194.1.1.0/24 is directly connected, Ethernet0/0//R3的192路由原本为IA类型（区域间），现在转为O类型（区域内），说明R3认为自已与192网段是直连的。

虚链路相当于将R3直接连接了AREA 0 与 AREA 4区域r4#sh ip ro4.0.0.0/24 is subnetted, 1 subnetsC 4.4.4.0 is directly connected, Loopback0O IA 193.1.1.0/24 [110/20] via 194.1.1.3, 00:03:40, Ethernet0/0O IA 192.1.1.0/24 [110/30] via 194.1.1.3, 00:03:25, Ethernet0/0C 194.1.1.0/24 is directly connected, Ethernet0/0//R4上192路由类型IA（区域间）最后我们将虚链路效果再与正常连接方式进行一下比对，如下图：验证如下：r1#sh ip ro1.0.0.0/24 is subnetted, 1 subnetsC 1.1.1.0 is directly connected, Loopback0O IA 193.1.1.0/24 [110/20] via 192.1.1.2, 00:00:41, Ethernet0/0 C 192.1.1.0/24 is directly connected, Ethernet0/0C 192.2.2.0/24 is directly connected, Ethernet1/0O IA 194.1.1.0/24 [110/20] via 192.2.2.4, 00:00:39, Ethernet1/0r2#sh ip ro2.0.0.0/24 is subnetted, 1 subnetsC 2.2.2.0 is directly connected, Loopback0C 193.1.1.0/24 is directly connected, Ethernet1/0C 192.1.1.0/24 is directly connected, Ethernet0/0O 192.2.2.0/24 [110/20] via 192.1.1.1, 00:01:04, Ethernet0/0 O IA 194.1.1.0/24 [110/30] via 192.1.1.1, 00:00:03, Ethernet0/0 r2#r3#sh ip ro3.0.0.0/24 is subnetted, 1 subnetsC 3.3.3.0 is directly connected, Loopback0C 193.1.1.0/24 is directly connected, Ethernet1/0O IA 192.1.1.0/24 [110/20] via 193.1.1.2, 00:01:31, Ethernet1/0O IA 192.2.2.0/24 [110/30] via 193.1.1.2, 00:01:15, Ethernet1/0O IA 194.1.1.0/24 [110/40] via 193.1.1.2, 00:00:15, Ethernet1/0r4#sh ip ro4.0.0.0/24 is subnetted, 1 subnetsC 4.4.4.0 is directly connected, Loopback0O IA 193.1.1.0/24 [110/30] via 192.2.2.1, 00:00:39, Ethernet1/0O 192.1.1.0/24 [110/20] via 192.2.2.1, 00:01:37, Ethernet1/0C 192.2.2.0/24 is directly connected, Ethernet1/0C 194.1.1.0/24 is directly connected, Ethernet0/0r5#sh ip ro5.0.0.0/24 is subnetted, 1 subnetsC 5.5.5.0 is directly connected, Loopback0O IA 193.1.1.0/24 [110/40] via 194.1.1.4, 00:00:52, Ethernet0/0O IA 192.1.1.0/24 [110/30] via 194.1.1.4, 00:00:52, Ethernet0/0O IA 192.2.2.0/24 [110/20] via 194.1.1.4, 00:00:52, Ethernet0/0C 194.1.1.0/24 is directly connected, Ethernet0/0如果上述方式还不容易理解，你也可以将virtual-link可以想象成：将R2与R3合并成一台路由器，如下图：r1#sh ip ro1.0.0.0/24 is subnetted, 1 subnetsC 1.1.1.0 is directly connected, Loopback0O IA 193.1.1.0/24 [110/20] via 192.1.1.2, 00:00:57, Ethernet0/0 C 192.1.1.0/24 is directly connected, Ethernet0/0O IA 194.1.1.0/24 [110/74] via 192.1.1.2, 00:00:24, Ethernet0/0r2#sh ip ro2.0.0.0/24 is subnetted, 1 subnetsC 2.2.2.0 is directly connected, Loopback0C 193.1.1.0/24 is directly connected, Ethernet1/0C 192.1.1.0/24 is directly connected, Ethernet0/0C 194.1.1.0/24 is directly connected, Serial2/0r3#sh ip ro3.0.0.0/24 is subnetted, 1 subnetsC 3.3.3.0 is directly connected, Loopback0C 193.1.1.0/24 is directly connected, Ethernet1/0O IA 192.1.1.0/24 [110/20] via 193.1.1.2, 00:01:06, Ethernet1/0 O IA 194.1.1.0/24 [110/74] via 193.1.1.2, 00:00:37, Ethernet1/0r4#sh ip ro4.0.0.0/24 is subnetted, 1 subnetsC 4.4.4.0 is directly connected, Loopback0O IA 193.1.1.0/24 [110/74] via 194.1.1.2, 00:00:17, Serial2/0O IA 192.1.1.0/24 [110/74] via 194.1.1.2, 00:00:17, Serial2/0C 194.1.1.0/24 is directly connected, Serial2/0。