From: Mark S. Detrick (mark@xxxxxxxxxxx)
Date: Sun Aug 15 1999 - 02:36:59 GMT-3
No, that is not correct.
The inverse mask is used only to tell the OSPF process which interfaces
belong in that process. That's it. Once an interface is in the OSPF
process adjacencies can be established and routes put in the routing table.
The routes put in the table are not effected by the inverse mask. Routes
put in the table are according to the IP/Mask set on the interface and/or
summaries.
0.0.0.0 can be used and still meet the requirements of the exam.
P.S. the interfaces mentioned above are only those that are on the same
router as the OSPF process. You don't need to specify interfaces of
connecting routers. For example, local router is .1 and remote router is
.2, just specify the local.
Mark Detrick
----- Original Message -----
From: Mark Mirrotto <mmirrott@stratos.net>
Cc: <ccielab@groupstudy.com>
Sent: Saturday, August 14, 1999 7:16 PM
Subject: Re: OSPF network; inverse mask question....
> If you use a 0.0.0.0 wildcard mask, won't that only advertise the
interface
> address by itself? And if so, does it truly meet the requirements of the
> question in the lab? I realize the interface will be reachable, but other
> address on the same subnet won't. Isn't that correct?
>
> Mark
> -----Original Message-----
> From: Mark S. Detrick <mark@detrick.com>
> To: Jason Aarons <jaarons@hotmail.com>; scotto@iworksys.com
> <scotto@iworksys.com>
> Cc: ccielab@groupstudy.com <ccielab@groupstudy.com>
> Date: Saturday, August 14, 1999 2:49 PM
> Subject: Re: OSPF network; inverse mask question....
>
>
> >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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