From: Mark S. Detrick (mark@xxxxxxxxxxx)
Date: Sat Aug 14 1999 - 15:35:21 GMT-3
Folks,
Actually, inverse masks are not limited to the ones below. It is just that
the ones below are the most useful. For example, you could use 0.0.0.6,
which makes the last bit an "I care" bit. The value of that bit is dictated
by the IP you place before it in the statement. In the case of 10.0.0.0,
all IPs with EVEN numbers (even because the last bit of the last octet is a
0 which implys even numbers) in the range 10.0.0.0 to 10.0.0.7.
Indeed, not very useful but thought I would mention it just for the
understanding of how it works. Any bit you make 0 in the mask uses the
corresponding bit value from the IP octet to designate which IPs will be
used in OSFP, for example. Any bit you make 1 is a don't care.
My suggestion for the test is to use 0.0.0.0 and specify all the interfaces
you want specifically (there aren't that many). That way there is no
confusion.
Mark Detrick
----- Original Message -----
From: Jason Aarons <jaarons@hotmail.com>
To: <scotto@iworksys.com>
Cc: <ccielab@groupstudy.com>
Sent: Tuesday, August 10, 1999 5:29 PM
Subject: Re: OSPF network; inverse mask question....
> Actually I tried 0.0.0.252; it isn't a valid reverse valid wildcard mask.
>
> Remember that OSPF uses a wildcard mask so the valid masks are below
>
> 255
> 127
> 63
> 31
> 15
> 7
> 3
> 1
> 0
>
>
>
> ----Original Message Follows----
> From: "Scott O'Donnell" <scotto@iworksys.com>
>
>
> >
>
> Or the Network statement could look like this.
>
> network 172.16.254.1 0.0.0.252 area 0
>
> Although it doesn't lend itself to easy reading.
>
> Scott
>
>
>
> > Try a wildcard mask of 0.0.0.3
> >
> > Antonio
> > ---------------------- Forwarded by Antonio Sabella/USC/AXE on 08/10/99
> 10:36
> > AM ---------------------------
> >
> > nobody@groupstudy.com on 08/10/99 10:05:23 AM
> > To: jaarons@hotmail.com@internet@WTAXE,
> > ccielab@groupstudy.com@internet@WTAXE
> > cc:
> > Subject: Re: OSPF network; inverse mask question....
> >
> > Your wild card mask is not including s0..
> >
> > ----Original Message Follows----
> > From: "Jason Aarons" <jaarons@hotmail.com>
> > Reply-To: "Jason Aarons" <jaarons@hotmail.com>
> > To: ccielab@groupstudy.com
> > Subject: OSPF network; inverse mask question....
> > Date: Wed, 04 Aug 1999 18:14:37 EDT
> >
> > interface Serial0
> > ip address 172.16.254.1 255.255.255.252
> > encapsulation frame-relay
> > ip ospf network point-to-point
> > !
> > router ospf 1999
> > network 172.16.254.0 0.0.0.252 area 0
> > !
> > ip classless
> > ip subnet-zero
> >
> > 1#show ip ospf int s0
> > Serial0 is up, line protocol is up
> > OSPF not enabled on this interface
> >
> > if I change the router ospf 1999, network 172.16.254.0 0.0.0.255 it
> works.
> > What am I not seeing ?
> >
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