From: Stephen C. Feldberg (scfeldberg@xxxxxxxxxxx)
Date: Wed Jan 02 2002 - 12:09:48 GMT-3
The inverse mask defines the scope of the interfaces that you wish to
inculde in the ospf process. Your first example will only match a single
address: 137.20.20.1 . Lets say that you have created four subnets of the
137.20.20.0 network: 137.20.20.0/26, 137.20.20.64/26, 137.20.20.128/26, and
137.20.20.192/26 and have asigned the first address in each subnet to an
interface on your OSPF router. If you used the 0.0.0.0 mask you would need
to enter four network statements that were an exact match to the addresses
assigned to each interface. This has the benefit of allowing only the
interfaces you specifiy to run OSPF. Using the inverse mask from your second
example (0.0.0.255) would match the interfaces in all four subnets- a
shortcut that would allow you to activate OSPF on all four subnets with a
single statement.
Steve
----- Original Message -----
From: "Williams, Glenn" <WILLIAMSG@PANASONIC.COM>
To: <ccielab@groupstudy.com>
Sent: Wednesday, January 02, 2002 9:51 AM
Subject: Simple OSPF question
> Hi,
>
> Usually when I enable ospf on an interface, for example if the interface
is
> 137.20.20.1/24, I would say:
>
> net 137.20.20.1 0.0.0.0 area x
>
> I could say:
>
> net 137.20.20.0 0.0.0.255 area x
>
> but what would I gain?
>
> Just one of those questions I've been meaning to ask.
>
> GW
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