OSPF Advertisement

[newnetman]

Hello All,

Can someone please help clarify the difference between:

network 0.0.0.0 0.0.0.0 area xx

network 0.0.0.0 255.255.255.255 area xx

When advertising networks in OSPF?

Many thanks in Advance

[Marwan ALshawi]

in the network field 0 mean any

in the wildcard field 255 means any

if helpful Rate

[newnetman]

Sir,

If in the wildcard field 255 means any, What would the following mean then?,

network 0.0.0.0 0.0.0.0 area xx

because i am still confused if 0.0.0.0 in the wildcard field means "specificity", what would it then care about in the network field with 0.0.0.0?.

Thanks

[Marwan ALshawi]

the mask in wild card 0.0.0.0 mean host

if u wanna advertise host u give it this wildcard

[ariesc_33]

this is actually confusing. i cant find any documentation so the best way to verify this is on a lab or actual scenario. if you encountered this on the actual network, then you definitely have a clue by using show ospf commands and see what is being advertise by the router.

[Danilo Dy]

I'm not sure about this, but I think if you type the following....

!

router ospf

network 0.0.0.0 0.0.0.0 area xx

....it will show in the "show run" as;

!

router ospf

network 0.0.0.0 255.255.255.255 area xx

[Edison Ortiz]

The IOS will change the command

network 0.0.0.0 0.0.0.0 area xx

to

network 0.0.0.0 255.255.255.255 area xx

As the first command isn't valid. The subnet portion will determine what to match from the network portion. If the network portion is all 0s, there is nothing to match so the correct subnet mask is 255 (don't care bits).

HTH,

__

Edison.

[Danilo Dy]

Thanks Ed, that confirms my theory :)

[bagvanliju]

HAi Edi,

That was really helpfull one ...

thanks ...

Lijesh.N.C