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jilahbg
Beginner

OSPF Area ID?

Hi

An OSPF area is generally defined as an integer, with the backbone area as "0". Some vendors uses dotted decimal (32 bit) instead, which means that the backbone area is named "0.0.0.0"

My question is: Is area "1" the same as "0.0.0.1" and how do I convert the Area ID:s between vendor equimpent that uses different syntax for the area ID?

Thanks for your help!

Regards, Jimmy Larsson

3 REPLIES 3
thisisshanky
Advisor

Hi,

OSPF area can be a decimal number or a a dotted number form (x.x.x.x).

Area 1 and Area 0.0.0.1 are totally different areas.

Sankar Nair
UC Solutions Architect
Pacific Northwest | CDW
CCIE Collaboration #17135 Emeritus

But area 0 and Area 0.0.0.0 are the same?

Hi, I'm afraid you are not correct.

Area 1 and Area 0.0.0.1 are the same.

See Routing TCP/IP, Volume I. by Jeff Doyle, page 458:

"Areas are identified by a 32-bit Area ID..... Area ID may be expressed either as a decimal number or in dotted decimal, and the two formats may be used together on Cisco routers.

....

For example, area 0 and area 0.0.0.0 are equivalent, as are area 16 and area 0.0.0.16, and area 271 and area 0.0.1.15. In each of this cases, the decimal format would probably be preferred. However, given the choice of area 32322243229 ans area 192.168.30.29, the latter would probably be chosen."

Regards,

Milan