From: Swan, Jay (jswan@sugf.com)
Date: Mon Oct 29 2007 - 11:52:02 ART
In OSPF, only intra-area routing is link-state. Inter-area routing
actually uses distance-vector logic. As such, inter-area routing is
subject to the same potential problems with routing loops as other
distance-vector protocols. OSPF avoids these by mandating loop-free
inter-area routing design.
Jay
#17783
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
CCIEin2006
Sent: Monday, October 29, 2007 7:12 AM
To: Cisco certification
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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