I think it originally was loop prevention in that in order to get to any other area you had to go through area 0. Since all paths lead through area 0 and area 0 has a complete view of it's own topology then no loops. The other areas may not know all the summarized topology beyond their boundary so they can not be trusted to make end to end decisions.
Now I believe this has changed some because not all traffic is required to traverse area 0 these days, just all routes. On Tue, Jan 4, 2011 at 4:52 PM, Sanjay Singh <[email protected]>wrote: > Hello ! > > Why area 0 is required in OSPF? > I have read multiple blogs but didn't find any satisfactory answer, some > says- > > + Area 0 implemented for loop prevention. if yes.. then a big HOW ?? > + Area 0 is implemented to allow a level of hierarchy and to allow OSPF > and > to provide summarisation/filtering across area boundaries.. if yes.. then > Cann't we implement hierarchy or summarization without area 0 ??? > + Design constraint.. if yes.. then WHAT is the design constraint.. there > must be some logical reason behind it ???? > -- > Regards, > *Sanjay Singh* > Mob-9717775461 > _______________________________________________ > For more information regarding industry leading CCIE Lab training, please > visit www.ipexpert.com > _______________________________________________ For more information regarding industry leading CCIE Lab training, please visit www.ipexpert.com
