Ospf passive interface vlan

Unanswered Question
Jun 7th, 2012


Our network is a ring with fiber optic. We have one 3560X per branch, they are connected with OSPF and ip segment /30.

The problem is that we are going to add switch 3560X on the ring, and they are not stackable, there will be a trunk between the two swither... So I have two routers ospf (3560X) to distribute the same network.... I made a test with packet tracer, it seems I need to put "passive-interface vlan x (data) where there will be one 3560X, and have to disable this CLI on the two 3560X that are connected in trunk and distribute the same data networks...

Is this a good way ?

There is a map of part of the network in attached piece.

Thanks for your help !



I have this problem too.
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Reza Sharifi Thu, 06/07/2012 - 16:20


Since you are running OSPF on all your device, all you need to do is to create a /30 subnet between the top and the bottom 3560s (in the middle) and turn on OSPF.  Also, on the 3560 on the far left of your drawing, replace the 0.255.255 with specific subnet (SVI) example:

and so on


GERALD LECAILLIER Thu, 06/07/2012 - 20:40


Thank you for your reply,

If i create ospf between top and bottom switch, there wont be problems as they have same networks and trunks between them?

Users on top and bottoms are in the same data vlans.




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