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Snika
Participant

OSPF area ID in IP address format ??

ospf-id-format.png

 

What is the difference between "area1" and "area 0.0.0.1"??

I'm not sure how to understand the IP address format of Area.

The device is Nexus.

4 ACCEPTED SOLUTIONS

Accepted Solutions
Martin L
VIP Advocate

there should not be any difference between 2 ways of doing same thing.

"area 0.0.0.1" means  "area 1"

 

Regards, ML
**Please Rate All Helpful Responses **

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Hello @Snika ,

the OSPF standard allows to write the OSPF area-id in dotted decimal format like an IP address.

And like an IP address in dotted decimal format you can have formulas for conversion.

So for example

area 1.0.0.0 is not area 1   but it is a huge number  1 * 2^24  = 16,777,216.

 

Area ids in dotted decimal format are used by other vendors and provide a way to document the address block that is within a non zero area.

For example if address block 172.17.0.0/16 is within an area instead of naming the area 3 we could name it

area 172.17.0.0 making the area id meaning the address block inside it.

 

Hope to help

Giuseppe

 

View solution in original post

balaji.bandi
VIP Expert

adding to @Giuseppe Larosa ,  there is a good tool I come across how you can calculate the area with dotted decimal to decimal

 

https://www.beyondcli.com/ospf-conversion/



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View solution in original post

KakaoTalk_20210302_155321868.png

 

im tested

solved

View solution in original post

5 REPLIES 5
Martin L
VIP Advocate

there should not be any difference between 2 ways of doing same thing.

"area 0.0.0.1" means  "area 1"

 

Regards, ML
**Please Rate All Helpful Responses **

View solution in original post

If so, for example, what is area, 1.0.0.0, 1.1.0.0, 1.1.1.1?

Hello @Snika ,

the OSPF standard allows to write the OSPF area-id in dotted decimal format like an IP address.

And like an IP address in dotted decimal format you can have formulas for conversion.

So for example

area 1.0.0.0 is not area 1   but it is a huge number  1 * 2^24  = 16,777,216.

 

Area ids in dotted decimal format are used by other vendors and provide a way to document the address block that is within a non zero area.

For example if address block 172.17.0.0/16 is within an area instead of naming the area 3 we could name it

area 172.17.0.0 making the area id meaning the address block inside it.

 

Hope to help

Giuseppe

 

View solution in original post

KakaoTalk_20210302_155321868.png

 

im tested

solved

View solution in original post

balaji.bandi
VIP Expert

adding to @Giuseppe Larosa ,  there is a good tool I come across how you can calculate the area with dotted decimal to decimal

 

https://www.beyondcli.com/ospf-conversion/



BB


*** Rate All Helpful Responses ***

View solution in original post