From: Price, Jamie (jprice@xxxxxxxxxxx)
Date: Sun Mar 05 2000 - 20:08:13 GMT-3
Title: RE: Virtual Links ?
Here's what I think, although I dont know how valid it is and would
appreciate any comments.
I think the diagram is lacking. Call the top router A, the bottom one
B. I'm assuming that there are more routers in both areas 0 and 1 and
routers A and B are NOT directly connected.
If packet enters RA (possibly as a default route from a stub) destined
for one of the subnets in Area 0 that swings off of (and is relatively
close to) RB then normally that packet would have to traverse the 56k
net to get to it. For RA to recognize RB as the optimal route for
such a packet would mean it would have to traverse Area 1 and would
then be considered an IA route (if such a thing was even
possible????????). I think that RA, seeing that it belongs to Area 0,
will push the packet into area 0 through its own interface because to
RA that is THE link to Area 0.
However, adding a virtual link to Area 0 from Area 1, between RA and
RB would enable the OSPF on RA to choose a route to the subnet off of
RB that would be more desirable to the routing process which is also
over the 10/100 Ethernet network.
Just some thoughts - if anyone who really knows wants to jump in I'd
appreciate the confirmation/contradiction.
You may also want to post the question to cisco-cert@cciecert.com. I
think that is the more "Caslow" oriented list. You never know - you
might get the man himself!!!!
Jamie
-----Original Message-----
From: Kevin Gannon
To: ccielab@groupstudy.com
Sent: 3/5/00 12:53 PM
Subject: Virtual Links ?
I am reading Caslows book at the moment and he has an example (p393)
of
two area with two routers each sitting on
both a 10Mb ethernet and also a 56k Wan media the 56k wan side is area
0
the otherside is area 1.
My question is, how is it supposed to improves routing behavior ?
Regards,
Kevin
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