Advanced IP Network Design (CCIE Professional Development)

Virtual Links

There are times when the core area becomes divided, or an area loses contact with the core—generally, when there is some network outage. For these situations, the designers of OSPF provided the virtual link. The virtual link acts as a tunnel, allowing traffic that needs to traverse to and from the core area to pass through another area.

Router A in Figure A-10 has gone down for some reason, effectively partitioning area 1 from the rest of the network (making it unreachable). The network administrator could, by configuring a virtual link between Router C and Router B across the backup link, make area 1 accessible until Router A could be repaired and restored to service.

Note

One of the most confusing aspects of configuring virtual ...