OSPF Areo 0 and Virtual links

[The_guroo_2]

guys basic question abt ospf virtual links.....for exaple three routers are connected A,B,C And B router serials are connected and are in areo the fethernet of the routers are in area 10 so do we need virtual connection to area 0 or not if yes why if not why??? whats the rule of thumb for virtual links......

[andrew.prince]

Read the below link - good examples and explainations:-

http://www.cisco.com/en/US/tech/tk365/technologies_configuration_example09186a00801ec9ee.shtml

HTH>

[Jon Marshall]

In OSPF all areas in the same AS must be physically connected to area 0 so a router (ABR - Area Border Router) that connects area 0 to area 10 for example would have at least one interface in area 0 and one interface in area 10.

Virtual links are used when there is no physical connection to area 0. See this attached doc for more details

http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080094aaa.shtml#virtuallinks

Note that virtual links are not good design. They are usually used as a temporary stop gap.

Jon

[paul.matthews]

Your question is not totally clear. The basic OSPF rule is that all areas shall be connected to the backbone. If you have an area that does not have a direct connection to the backbone, to allow connectivity to other areas you would need to configure a virtual link.

The rule of thumb for virtual links? They are for emergencies, temporary use or for people that cannot design networks.