CISCO:
     RA;
         (config)#router ospf 1
         (config-route)#network 192.168.0.0 0.0.0.255 a 2
         (config-route)#network 192.168.1.0 0.0.0.255 a 1
         (config-route)#area 1 virtual-link 192.168.2.2 //192.168.2.2,RB的router-id
     RB:
         (config)#router ospf 1
         (config-route)#network 192.168.1.0 0.0.0.255 a 1
         (cofnig-route)#network 192.168.2.0 0.0.0.255 a 0
         (config-route)#area 1 virtual-link 192.168.1.1   ///192.168.1.1 RA,的router-id
       RC:
         (config)#router ospf 1
         (config-route)#network 192.168.2.0 0.0.0.255 a 0
         (config-route)#network 192.168.3.0 0.0.0.255 a 0