From: Bob Reed (bobr@xxxxxxxxxxx)
Date: Sat Apr 29 2000 - 19:57:12 GMT-3
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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