From: Bob Reed (bobr@xxxxxxxxxxx)
Date: Sat Apr 29 2000 - 22:08:24 GMT-3
The gross example would be if you had a router in which you wanted all
interfaces in the same area. You could do
network 0.0.0.0 255.255.255.255 area x
it would then match all the interfaces. Everything else is inbetween and
could be used to just match a few interfaces or just one.
Bob
----- Original Message -----
From: Kinton Connelly <kinton@oldmedia.com>
To: Bob Reed ; <bobr@mmcable.com>; <ccielab@groupstudy.com>
Sent: Saturday, April 29, 2000 6:43 PM
Subject: Re: OSPF and wild card bits confusion
> Thanks for the explanation, Bob. Just to check my own sanity, I went back
> to the routers and changed the wildcard bits on that ospf config entry to
> see if anything would change. Here's what I found:
>
> "network 137.20.25.0 0.0.0.255 area 2" gave me this in another router's
> route table:
> O IA 137.20.25.0/24 [110/128] via 137.20.100.34, 00:33:12, Serial0
>
> and
>
> "network 137.20.25.2 0.0.0.0 area 2" gave me this in another router's
route
> table:
> O IA 137.20.25.0/24 [110/128] via 137.20.100.34, 00:00:05, Serial0
>
> I can see how that works now - the route goes in the table based on the
> subnet mask of the interface - not based on your ospf config entry.
>
> But now I have to ask - why would you ever specify anything but 0.0.0.0
for
> wildcard bits? In the same example I mentioned previously, why didn't they
> just use 0.0.0.0 for all the following entries?:
>
> > > router ospf 1
> > > network 137.20.25.2 0.0.0.0 area 2
> > > network 137.20.64.0 0.0.15.255 area 0
> > > network 137.20.100.32 0.0.0.31 area 1
> > > network 137.20.224.5 0.0.0.0 area 0
> > > network 137.20.240.1 0.0.0.0 area 0
>
> Ok, I just finished reading a little in Doyle's TCP/IP book and he cleared
> it up for me some more. But I still have the question: what's the best
> practice to use - when I'm in the lab, should I just use 0.0.0.0 for
> everything?
>
> Thanks,
>
> Kinton
>
>
> At 4/29/00, you wrote:
> >The format "network ip-address wildmask" is used to specify which
interfaces
> >are in which areas. This is different from RIP, IGRP, EIGRP which use the
> >network statement to say which addresses they are routing.
> >
> >By using the /32 format, there is no question of which interface you
> >specify. Remember that the order of the network statements can affect
the
> >outcome when you are using the masks as other than /32. This is because
for
> >each interface, the network statements are scanned until a match is
found,
> >or there are no more.
> >
> >If you had an interface address of 132.10.100.1 and used the following,
> >
> >network 132.10.100.0 0.0.0.255 area 3
> >network 132.10.100.1 0.0.0.0 area 0
> >
> >the interface would be in area 3, not 0.
> >
> >Bob Reed
> >
> >
> >----- Original Message -----
> >From: Kinton Connelly <kinton@oldmedia.com>
> >To: <ccielab@groupstudy.com>
> >Sent: Saturday, April 29, 2000 5:23 PM
> >Subject: OSPF and wild card bits confusion
> >
> >
> > > I've been going through the CCIE Boot Camp practice labs and just ran
into
> > > something that has me confused. On lab 8a, I don't understand where
> >they're
> > > getting the wild card bits for the OSPF areas. I've included a bit of
> > > sample code from router 5 below.
> > >
> > > Here's what I don't understand: normally, if you give me an interface
like
> > > Serial1 below and tell me to put it in OSPF Area 2, I'll take the
> >interface
> > > address:
> > >
> > > 137.20.25.2/24
> > >
> > > and turn it into this OSPF statement:
> > >
> > > network 137.20.25.0 0.0.0.255 area 2
> > >
> > > But as you can see below, sometimes they do it this way and sometimes
they
> > > don't. Why? Why put it in there as "network 137.20.25.2 0.0.0.0 area
2" -
> > > that would be the entry for a /32 network.
> > >
> > > Thanks for any help,
> > >
> > > Kinton
> > >
> > >
> > > R5
> > > --
> > > interface Loopback0
> > > ip address 137.20.240.1 255.255.240.0
> > > !
> > > interface Ethernet0
> > > ip address 137.20.64.5 255.255.240.0
> > > !
> > > interface Serial0.1 multipoint
> > > ip address 137.20.100.34 255.255.255.224
> > > !
> > > interface Serial0.2 point-to-point
> > > ip address 137.20.200.17 255.255.255.240
> > > !
> > > interface Serial1
> > > ip address 137.20.25.2 255.255.255.0
> > > !
> > > interface BRI0
> > > ip address 137.20.224.5 255.255.240.0
> > > !
> > > router ospf 1
> > > network 137.20.25.2 0.0.0.0 area 2
> > > network 137.20.64.0 0.0.15.255 area 0
> > > network 137.20.100.32 0.0.0.31 area 1
> > > network 137.20.224.5 0.0.0.0 area 0
> > > network 137.20.240.1 0.0.0.0 area 0
> > >
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