From: William Nellis (nellis_iv@yahoo.com)
Date: Mon Oct 29 2007 - 21:39:48 ART
Inter area ospf is not completely link state because they do not all have the same view of the topology to compute SPF from and could be vulnerable to routing loops as such.
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r/s
William Nellis IV
nellis_iv@yahoo.com
----- Original Message ----
From: CCIEin2006 <ciscocciein2006@gmail.com>
To: Cisco certification <ccielab@groupstudy.com>
Sent: Monday, October 29, 2007 6:12:10 AM
Subject: Why must all areas connect to Area 0?
Hi folks,
I was reading over Jeff Doyle's blog and came across his favorite interview
question:
Why does OSPF require all traffic between non-backbone areas to pass through
a backbone area (area 0)?
Answer:
Because inter-area OSPF is distance vector, it is vulnerable to routing
loops. It avoids loops by mandating a loop-free inter-area topology, in
which traffic from one area can only reach another area through area 0.
Can someone elaborate on that answer a little bit? Exactly how does having a
connection to Area0 prevent routing loops? Is it similar to spanning tree in
the area 0 is the root of the spanning tree?
Also this answer does not take into consideration redistribution from
another routing protocol right?
Thank You
Here is the article:
http://www.networkworld.com/community/node/19293
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