思科配置案例：不连续区域 0 的虚链路

思科配置案例：不连续区域 0 的虚链路

本实验中区域 1 为转接区域。

3.实验步骤

（1）步骤 1：配置路由器 R1

R1(config)#router ospf 1

R1(config-router)#router-id 1.1.1.1

R1(config-router)#network 1.1.1.0 0.0.0.255 area 0

R1(config-router)#network 192.168.12.0 0.0.0.255 area 0

（2）步骤 2：配置路由器 R2

R2(config)#router ospf 1

R2(config-router)#router-id 2.2.2.2

R2(config-router)#network 2.2.2.0 0.0.0.255 area 0

R2(config-router)#network 192.168.12.0 0.0.0.255 area 0

R2(config-router)#network 192.168.23.0 0.0.0.255 area 1

R2(config-router)#area 1 virtual-link 3.3.3.3 //配置虚链路

【技术要点】

配置虚链路的时候，“virtual-link”后一定要互指对方的路由器 ID。

（3）步骤 3：配置路由器 R3

R3(config)#router ospf 1

R3(config-router)#router-id 3.3.3.3

R3(config-router)#network 3.3.3.0 0.0.0.255 area 0

R3(config-router)#network 192.168.23.0 0.0.0.255 area 1

R3(config-router)#network 192.168.34.0 0.0.0.255 area 0

R3(config-router)#area 1 virtual-link 2.2.2.2

（4）步骤 4：配置路由器 R4

R4(config)#router ospf 1

R4(config-router)#router-id 4.4.4.4

R4(config-router)#network 4.4.4.0 0.0.0.255 area 0

R4(config-router)#network 192.168.34.0 0.0.0.255 area 0

4.实验调试

（1）show ip route

R1#show ip route ospf

2.0.0.0/24 is subnetted, 1 subnets

O 2.2.2.0 [110/65] via 192.168.12.2, 00:04:42, Serial0/0/0

3.0.0.0/24 is subnetted, 1 subnets

O 3.3.3.0 [110/129] via 192.168.12.2, 00:04:42, Serial0/0/0

4.0.0.0/32 is subnetted, 1 subnets

O 4.4.4.4 [110/193] via 192.168.12.2, 00:04:42, Serial0/0/0

O IA 192.168.23.0/24 [110/128] via 192.168.12.2, 00:04:42, Serial0/0/0

O 192.168.34.0/24 [110/192] via 192.168.12.2, 00:04:42, Serial0/0/0

从以上输出可以看出通过虚拟链路将两个不连续的区域 0 连接起来。

（2）show ip ospf virtual-links

R2#show ip ospf virtual-links

Virtual Link OSPF_VL0 to router 3.3.3.3 isup

Run as demand circuit

DoNotAge LSA allowed.

Transit area 1, via interface Serial0/0/1, Cost of using 64

Transmit Delay is 1 sec, State POINT_TO_POINT,

Timer intervals configured, Hello 10,Dead 40, Wait 40, Retransmit 5

Hello due in 00:00:03

Adjacency State FULL (Hello suppressed)

Index 2/3, retransmission queue length 0, number of retransmission 1

First 0x0(0)/0x0(0) Next 0x0(0)/0x0(0)

Last retransmission scan length is 1, maximum is 1

Last retransmission scan time is 0 msec, maximum is 0 msec

以上输出表明了虚链路的基本信息。

（3）show ip ospf database

R2#show ip ospf database

OSPF Router with ID (2.2.2.2) (Process ID 1)

Router Link States (Area 0)

Link ID   ADV Router   Age   Seq#              ChecksumLink count

1.1.1.1   1.1.1.1       668   0x80000003       0x00ABE6  3

2.2.2.2   2.2.2.2       537   0x80000007       0x00EEB6   4

3.3.3.3   3.3.3.3        1      (DNA) 0x80000014   0x00C591  4

4.4.4.4 4.4.4.4 6 (DNA) 0x80000003 0x00AB8E   3

Summary Net Link States (Area 0)

Link ID ADV Router Age Seq# Checksum

192.168.23.0 2.2.2.2 608 0x80000001 0x002054

192.168.34.0 3.3.3.3 16 (DNA) 0x80000001 0x00026E

Router Link States (Area 1)

Link ID ADV Router Age Seq# ChecksumLink count

2.2.2.2 2.2.2.2 562 0x80000002 0x00ED952

3.3.3.3 3.3.3.3 553 0x80000003 0x008BF12

以上输出表明虚链路的路由被拉进区域 0，并带有“（DNA）”标记，表示不老化。