Ospf Virtual link issues ?

[ganpatspatil]

Pls find attachment for Virtual link problem......

[ahmet-saat]

Hi,

We use virtual link where some areas have not a direct connection to the backbone area (Area 0). So here in what you sent, area 2 does not have a connection to Area 0, so virtual-link is necessary.

Router 3 has not a direct connection to Area 0 actually, but It thinks that it has a direct connection to Area 0 through Virtual links. All communication between Router 1 and Router is tunneled through virtual link thats why u see that is indicated "0" in the Router 3's routing table.

pls rate if it helps.

[ganpatspatil]

Hi,

Thanks ...let me know how r1 showing 12.0.0.0 as "OIA",this is also show as "O" as r3 is directly connected to R1 over virtual link...

O IA 12.0.0.0/8 [110/75] via 5.0.0.2, 00:38:02, Serial2/1/0

[rajinikanth]

Hi,

OSPF requires that all areas be connected to area 0 and that area 0

must be contiguous. When this is not possible, you can use a virtual

link to bridge across an intermediate area.

Verify that the virtual link is up with the show ip ospf virtual-links

command. Additionally, virtual interfaces are treated as actual interfaces

by the OSPF process, and thus, their status can be verified with the

show ip ospf interface interface-id command.

hth

Raj

[sundar.palaniappan]

In your setup all 3 routers are ABRs;

R1 is part of area 1 & 0

R2 is part of area 1 & 0

R3 is part of area 1, 2 & 0

12.0.0.0/8 is part of area 2 and therefore it's an 'OIA' (inter-area) route as neither R1 or R2 are part of area 2.

HTH

Sundar