我们知道在OSPF配置当中,非骨干区域必须和骨干区域直接相连,若不与骨干区域直接相连,则需要配置虚链路,本篇文章主要介绍OSPF虚链路配置命令。
实验配置如下图:
实验说明如下:
1.路由器R1、R2在0区域,路由器R2、R3、R4在234区域,路由器R4、R5在45区域。
2.45区域没有与骨干区域直接相连,因此在不引入外部路由的情况下,需要在路由R2、R4上配置虚链路。
第一步,实验基本配置如下:R1
system-view
sysname R1
user-interface console 0
idle-timeout 1000
quit
interface GigabitEthernet0/0/2
ip address 192.168.1.254 255.255.255.0
interface GigabitEthernet0/0/1
ip address 192.168.17.1 255.255.255.0
interface GigabitEthernet0/0/0
ip address 192.168.12.1 255.255.255.0
quit
R2
system-view
sysname R2
interface GigabitEthernet0/0/1
ip address 192.168.12.2 255.255.255.0
interface GigabitEthernet0/0/0
ip address 192.168.23.2 255.255.255.0
quit
R3
system-view
sysname R3
interface GigabitEthernet0/0/1
ip address 192.168.23.3 255.255.255.0
interface GigabitEthernet0/0/0
ip address 192.168.34.3 255.255.255.0
quit
R4
system-view
sysname R4
interface GigabitEthernet0/0/1
ip address 192.168.34.4 255.255.255.0
interface GigabitEthernet0/0/0
ip address 192.168.45.4 255.255.255.0
quit
R5
system-view
sysname R5
interface GigabitEthernet0/0/1
ip address 192.168.45.5 255.255.255.0
interface GigabitEthernet0/0/2
ip address 192.168.5.254 255.255.255.0
interface GigabitEthernet0/0/0
ip address 100.1.1.5 255.255.255.0
quit
第二步,配置OSPF;配置命令如下:
R1
ospf 1 router-id 1.1.1.1
area 0
network 192.168.12.0  0.0.0.255
network 192.168.1.0  0.0.0.255
R2
ospf 1 router-id 2.2.2.2
area 0
network 192.168.12.0  0.0.0.255
area 234
network 192.168.23.0  0.0.0.255
R3
ospf 1 router-id 3.3.3.3
area 234
network 192.168.23.0  0.0.0.255
network 192.168.34.0  0.0.0.255
R4
ospf 1 router-id 4.4.4.4
area 234
network 192.168.34.0  0.0.0.255
area 45
network 192.168.45.0  0.0.0.255
R5
ospf 1 router-id 5.5.5.5
area 45
network 192.168.45.0  0.0.0.255
network 192.168.5.0  0.0.0.255
quit
查看R1的路由表,如下:[R1]display ip routing-table protocol ospf 
Route Flags: R - relay, D - download to fib
Public routing table : OSPF
Destinations : 2        Routes : 2        
OSPF routing table status : <Active>
Destinations : 2        Routes : 2
Destination/Mask Proto Pre Cost Flags NextHop Interface
192.168.23.0/24  OSPF    10   2           D   192.168.12.2    GigabitEthernet
0/0/0
192.168.34.0/24  OSPF    10   3           D   192.168.12.2    GigabitEthernet
0/0/0
 分析:由于45区域没有与骨干0区域直接相连,因此R1上面没有45区域的路由信息。
第三步,配置虚链路,即vlink-peer。分别在R2、R4上配置vlink-peer:
R2
ospf 1
area 234
vlink-peer 4.4.4.4
R4
ospf 1
area 234
vlink-peer 2.2.2.2
验证:
    查看R1的路由表,如下:[R1]display ip routing-table protocol  ospf 
Route Flags: R - relay, D - download to fib
Public routing table : OSPF
Destinations : 4        Routes : 4        
OSPF routing table status : <Active>
Destinations : 4        Routes : 4
Destination/Mask Proto Pre Cost Flags NextHop Interface
192.168.5.0/24  OSPF    10   5           D   192.168.12.2    GigabitEthernet0/0/0
192.168.23.0/24  OSPF    10   2           D   192.168.12.2    GigabitEthernet
0/0/0
192.168.34.0/24  OSPF    10   3           D   192.168.12.2    GigabitEthernet
0/0/0
192.168.45.0/24  OSPF    10   4           D   192.168.12.2    GigabitEthernet
0/0/0
OSPF routing table status : <Inactive>
Destinations : 0        Routes : 0
测试PC1、PC2的网络联通性:
总结
        查看R4的路由信息:[R4]display ospf brief
 OSPF Process 1 with Router ID 4.4.4.4
     OSPF Protocol InformationRouterID: 4.4.4.4          Border Router:  AREA 
Multi-×××-Instance is not enabled
Global DS-TE Mode: Non-Standard IETF Mode
Graceful-restart capability: disabled
Helper support capability  : not configured
Applications Supported: MPLS Traffic-Engineering 
Spf-schedule-interval: max 10000ms, start 500ms, hold 1000ms
Default ASE parameters: Metric: 1 Tag: 1 Type: 2
Route Preference: 10 
ASE Route Preference: 150 
SPF Computation Count: 14    
RFC 1583 Compatible
Retransmission limitation is disabled
Area Count: 3   Nssa Area Count: 0 
ExChange/Loading Neighbors: 0
Process total up interface count: 3
Process valid up interface count: 2
 分析得出:
      R4路由状态以变为区域ABR,即虚链路使得R4直接与骨干区域相连。原文:http://blog.51cto.com/11806823/2327227