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In OSPF why we create Area 0 ? If i do not want to create can i start area 1

 

Please tell me if we are using OSPF protocol and i do not want to create area 0? is it possible ? can i start area1 so on.

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Rising star

Hello,See link below http:/

Hello,

See link below 

http://www.cisco.com/c/en/us/support/docs/ip/open-shortest-path-first-ospf/7039-1.html

Info below came from link above.

 

"Backbone and Area 0

OSPF has special restrictions when multiple areas are involved. If more than one area is configured, one of these areas has be to be area 0. This is called the backbone. When designing networks it is good practice to start with area 0 and then expand into other areas later on. 

The backbone has to be at the center of all other areas, i.e. all areas have to be physically connected to the backbone. The reasoning behind this is that OSPF expects all areas to inject routing information into the backbone and in turn the backbone will disseminate that information into other areas. The following diagram will illustrate the flow of information in an OSPF network:"

 

Hope this helps,

Please rate helpful posts 

Thanks

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Hi Junaid, Area 0 is must

Hi Junaid,

 

Area 0 is must require for ospf. So it is also known as “Backbone Area”.

As ospf rule, all other areas must have a connection with area 0.

 

Please find attached .docx file.

 

Regards,

Khaleelur Rahman

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Thank you

Thank you

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Cisco Employee

Junaid,Most of the people ask

Junaid,

Most of the people ask this question...and the answer is that "NO" . The OSPF is designed in such a way that it needs to have the area 0 to work followed by other areas. You might have heard or read that if any area wants to talk to other area you need to go through area 0 for this we have some workaround by using virtual links or gre tunnel.

But configuring OSPF without area 0 will not work at all.

 

HTH

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VIP Expert

DisclaimerThe Author of this

Disclaimer

The Author of this posting offers the information contained within this posting without consideration and with the reader's understanding that there's no implied or expressed suitability or fitness for any purpose. Information provided is for informational purposes only and should not be construed as rendering professional advice of any kind. Usage of this posting's information is solely at reader's own risk.

Liability Disclaimer

In no event shall Author be liable for any damages whatsoever (including, without limitation, damages for loss of use, data or profit) arising out of the use or inability to use the posting's information even if Author has been advised of the possibility of such damage.

Posting

"It depends".  As the other posters have already noted, OSPF area zero is required to allow multiple OSPF areas to normally intercommunicate (using the same OSPF process).  If you're going to just have a single OSPF area, it doesn't have to be area zero.  Whether to start with area zero, or not, depends on how you anticipate your topology growing.  (When you go to an OSPF multiple area topology, you'll likely need to migrate some routers into a new area number, ideally, you'll want to migrate as few routers as possible.)

One way to have different OSPF areas intercommunicate, without having an area zero, would be to have each OSPF area in its own OSPF process and redistribute between them.  Not something you would normally do unless you have some special needs for route filtering (which can also be done on ABRs, although ASBRs might be a little more flexible).

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