From: Adam Crisp (adam.crisp@totalise.co.uk)
Date: Thu Sep 12 2002 - 07:27:41 GMT-3
Imagine you have a NSSA/STUB area, with 2 ABR's, routerA and routerB that
advertise a default route.....
Also imagine that Router A and RouterB have loopback addresses in area X
(not backbone)
If for any reason RouterA looses it's connection to the backbone, then it
will stop advertising it's default route, and RouterB will carry on working.
and visa vera. If RouterA has it's loopback ion Area 0, then it will always
be connected to the backbone, and will therefore carry on advertising the
default route and the network will break.
I think therefore that it is best if loopback addresses are not in the
backbone for ABR's.
You need to be carefull if the ABR's are summerising an address range in
area. Ensure that the Loopback addresses in use are "out of band" and do not
fall inside the summary route, othewise the example above will break in
reverse if RouterA (orB) looses it's connection to area X.
Hope this helps
Adam
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
Paul Grey
Sent: 12 September 2002 10:49
To: ccielab@groupstudy.com
Subject: OSPF Area Allocation for Loopbacks
Can anyone cast some light on good/bad practices for allocating OSPF
loopbacks in to areas?
Eg. Pros/cons of placing loopback into backbone (Area 0) or non-backbone
areas, etc.
TIA
Paul
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