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Would somebody do me a favour about my OSPF network design?

Thank you for checking out my question.

Please check the topo below.

******************A1 /[==]********************

*************Area 0 / [==]A2 *****************

************B1 [==]/ ***| ******* **************

***Area b**B2 [==]****| ******Area a*********

*******************C1[==] ********************

****************** C2 [==] ********************

Maybe you are not quite clear yet,let me explain in more detail.

A,B and C are three sites of my network, A1 and B1 are the

backbone routers,which belong to the area 0,and meanwhile

as A2 and B2,they belong to the area a and area b respectively.

C1 and C2 belong to the area a.

Now there is a link between A1 and B1,the interfaces of these two routers

connecting this circuit are configured into area 0. But the problem is that this

link is not very reliable, so I want to do a backup between these two sites, but adding another link between A1 and B1 is pretty expensive,so I consider if I can put a link between B2 and C2,then there will be a alternate path connecting A2 and B2 as well,and more important is that will be more affordable.

Do you think I could do it? and if yes,how to?


Re: Would somebody do me a favour about my OSPF network design?

Sounds like you are looking to set up a virtual link in OSPF. A quick search on for "ospf virtual link" will get you a number of references and design examples. There are many choices and tradeoffs involved, so make sure you understand what you are doing before putting it into production as an inappropriate design could degrade rather than enhance reliability.

Good luck and have fun!

Vincent C Jones


Re: Would somebody do me a favour about my OSPF network design?

This is an odd situation that someone else asked about no tvery long ago. He could not get it working and I'm not sure he ever did. Putting the backup link where you are suggesting would make the area directly connected to area0 through a2 and virtually connected through c2. I dont know if ospf can deal with that.

You'd be better off if you could somehow link c2's new interface into area 0 on b1, or b2 to a1. I dont know how that affects the cost but the idea is to link into area 0.

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