how can we define area 30.0.0.0 in place of area AreaID in below command

[mirzaakberali]

router ospf 1

router-id 155.145.10.185

log-adjacency-changes

network 155.145.0.0 0.0.255.255 area 30.0.0.0

distance ospf external 130

[mheusinger]

What is the problem? The config looks fine.

[mirzaakberali]

Hello,

I was not aware that instead of area 30 we can use area 30.0.0.0 .

[mirzaakberali]

Hello All,

I am able to got he Answer....here is the answer...........

Cisco IOS? software supports area IDs expressed in IP address format or decimal format, for example, area 0.0.0.0 is equal to area 0. So the 30.0.0.0 is area 30.

[pkhatri]

Strictly speaking, that is not quite correct. The area 30 (which is in decimal) is actually 0.0.0.30 when translated to dotted octet notation. Which means that area 30.0.0.0 is actually 256*256*256*30 = area 503316480 in decimal.

Hope that helps...

Paresh

PS> Pls do rate helpful posts...

[mirzaakberali]

Hello,

Can you tell me what is the meaning of area 30.0.0.0 in below command.

network 155.145.0.0 0.0.255.255 area 30.0.0.0

Can you plz explain your above statement.

[pkhatri]

Firstly, you should not read too much into the actual number that an OSPF area is given - the only important thing that the identifier does it to distinguish one area from another (the actual numbers are really quite meaningless and you may as well give them names for the function they serve).

Having said that, your network statement will effectively enable OSPF operation over all interfaces with an IP address that falls within 155.145.0.0 and 155.145.255.255. In addition, it will place these interfaces in OSPF area 30.0.0.0.

Pls do remember to rate posts.

Paresh

[mirzaakberali]

I know how ospf network command works in ospf ,as I seen Do you mean area 30.0.0.0 is = area 30 ?

Regards,

Akber.

[pkhatri]

Not quite, if you look back at my first post, you'll see that 30.0.0.0 is not area 30.

Area 30 in dotted octet notation is actually 0.0.0.30.

Paresh

PS> Pls rate all posts..

[mirzaakberali]

Paresh,

can u tell me what is this command meaning

network 155.145.0.0 0.0.255.255 area 30.0.0.0,

specifically wht is the meaning of area 30.0.0.0?

[pkhatri]

I'm obviously not answering your question correctly :-), but it's probably because I can't quite say what your actual question is...

The 'area 30.0.0.0' bit simply means that the network statement refers to OSPF area 30.0.0.0, which in decimal is area 503316480.

Paresh

[mirzaakberali]

Dear Paresh,

Let me explain you my question --

why we are using 30.0.0.0 below inplace of some number

network 155.145.0.0 0.0.255.255 area 30.0.0.0

Ex:-

Normally the command would be

network 155.145.0.0 0.0.255.255 area 1

[pkhatri]

Alright, that's a lot clearer...

There is no particular technical reason why one would use the first format in place of the other. Both are equally valid and in fact, they both end up being stored internally as a 32-bit number. It is merely a matter of convention as to which format you use. The bottom line is that either form is valid and there are no real reasons why one would use one format instead of another.

Hope that helps.

Paresh

PS. Pls do rate posts

[mirzaakberali]

hi,can any one tell me how do we calculate cost on a serial interface in ospf routing.