Regarding Ospf Virtual Link

[shelkey007]

Recently in interview I was asked , how many virtual links can we have in ospf ? is there any limitation in ospf virtual link ? I searched in google but did not find any answer can someone let me know ASAP . 

[Mark Malone]

Limitation would be it cant be connected across multiple transit areas

regarding max virtual links I would have thought that really depended on the topology in place , its just a logical neighbour, they say no more than 100 neighbours per area but that can depend on your routers too what there spec is

[shelkey007]

Just want to understand by an example , as per below setup can we have a virtual link between area0 and area3 ? if yes then how ? and if no then why ? 

R1<---area0-->R2<---area1--->R3<---area2-->R4<---area3-->R5 

[Mark Malone]

No you can't it's a limitation of the feature , 1 area equals a transit area , A virtual link can only be created across 1 transit area not 2 or more

If you had to have that design you could use gre tunnels to connect back to area 0

[shelkey007]

Thanks Mark ... 

[Julio E. Moisa]

Hi

Actually OSPF Virtual link is not part of a good design, Now how many?, it basically depends of your topology, but As I mentioned previously Virtual links are not part of a good design it is used as a temp solution.

In order to create virtual links remember to use the OSPF router-id  to establish the adjacency.

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