Subject: OSPF Virtual link question

From: abc xyz <[email-masked]>
Date: Mon, 27 Oct 2003 16:10:12 +0000

Hi All,

I had a question regarding OSPF Virtual links, consider the following
network diagram:

      192.168.1.1_______area0______192.168.1.10
               ____|____                ____|____
              |   RUT    |              |    TR1      |
              |_______|              |_________|
          |                 |
           172.20.5.1_____area1_____172.20.5.1

A virtual link is configured across area 1 between the RUT & TR1.  When I
run my code I end up adding the route to TR1 via area 0 since it's the same
cost as across area 1.  As a result of this my virtual link never comes up
because it does not know how to get to TR1 from area 1.  Could you please
point me to the section in RFC 2328 that deals with this case?

Thanks for your time.

Regards,
Archana

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From: Acee Lindem <[email-masked]>
Date: Mon, 27 Oct 2003 12:21:43 -0500

Hi Archana,

>      192.168.1.1_______area0______192.168.1.10

While it may not be obvious, the first paragraph on page 109 covers this
case:

    The set of paths to use for a destination may vary base on the OSPF
     area to which the paths belong. This means that there may be multiple
     routing table entries for the same destination, depending on the values
     of the next field.

As far as implementation, I recommend you maintain a separate per-area
routing table for routers.