ospf passive interface

Unanswered Question
Apr 11th, 2007

Hi all,

From the book, Passive interface purpose is to stop individual interfaces from developing adjacencies in an OSPF network

I am not fully understand it, how about we can simply not advertise the directly network

(e.g. RouterA -<>-RouterB ) --we can simply not add under ospf 1 of RouterA or

add under ospf 1 of RouterB. Then result also can avoid two router become ospf neighbor

I have this problem too.
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rais Wed, 04/11/2007 - 10:17

Downside will be that the Routers connected to Router A (or B), if any, will have no knowledge of subnet then.


owaisberg Wed, 04/11/2007 - 10:33

In your specific scenario both methods of

using passive-interface or not advertising will have the same result

as inability to establish adjacency and no

LSA sent on that link. However, it can be a

scenario when let's say your router A

has multiple interfaces and use one network

statement to place them all into OSPF process, however one of the interfaces has

to be excluded from OSPF processing...then

passive-interface command comes very handy

as allows you to remove that specific interface without much modifications within

OSPF process.



balajitvk Wed, 04/11/2007 - 10:37

Dear Benny,

There is a difference,

To disable sending routing updates on an interface, use the passive-interface command. If you disable the sending of routing updates on an interface, the particular subnet will continue to be advertised to other interfaces since network command is there.

When you give no network command for that subnet, that link state info. won't be advertised to other ospf enabled routers too thro. other ospf enabled interfaces.

Hope it clears,

Rate if it does,


devang_etcom Wed, 04/11/2007 - 11:17


In OSPF when you configure any interface as a passive interface then it will stop sending the OSPF packet through that interface so if the neighboring router which is not receving update or any other packet from the locar router about the ospf then it will break the adjancency with it...

and not adding with network command it will avoid to send the update of those network...


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