From: George Cassels (glcassels3@nc.rr.com)
Date: Wed Jun 22 2005 - 08:28:29 GMT-3
I would say only if the requirements tell you that all IPs must be sent
with their configured subnet mask would you need to worry about doing
the ip ospf network point-to-point command. Also I may be off but you
seem to be saying that the subnet mask in the network command under OSPF
has to match up with the configured network mask on the interface. If
that is the case of what you are saying it is not correct. You could
match 1.X.X.X networks on your router with 1.0.0.0 0.255.255.255. So
for instance if I have 1.1.1.1/24, 1.2.2.x/24, and 1.3.3.0/24 I could
match them all with 1.0.0.0 0.255.255.255 area 0. You can also use the
network command 0.0.0.0 255.255.255.255 which will match every
configured IP on your router. If I remember right sequence does matter
so you need to be careful on how exactly you enter the network
statements. This is because a more general statement like 0.0.0.0
255.255.255.255 first will cause the router to never reach the more
specific statement if they are in different areas.
I did run into a do it lab that had isis running between like R1 and R2
and ospf running between R2 and R3. What network command you put into
the ospf network statement would dictate whether R3 had to go through R2
(the redistributing router) or straight to R1 since they are all on the
same subnet. I don't remember the exact IPs, but by using the network
command 172.16.1.0 0.0.0.255 area 0 it allowed R3 to go straight to R1.
Where as if you use the network command of say 172.16.1.2 0.0.0.0 area 0
on R2 it would make the next hop IP on R3 R2's address.
Way too much info for your question...Sorry,
George
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
yesar1@yahoo.com
Sent: Wednesday, June 22, 2005 12:08 AM
To: ccielab@groupstudy.com
Subject: /32 vs /24 for loopback and OSPF
Greetings,
When asked to configure loopback interface as part of OSPF area, when
should I be
-using /32 mask for the IP address and subsequently 0.0.0.0 in the ospf
network statement
(e.g.
int lo0
ip add 1.1.1.1 255.255.255.255
router ospf 0
network 1.1.1.1 0.0.0.0 area 0.0.0.0)
vs
-using /24 mask and 0.0.0.255 in the ospf network statement
(e.g.
int lo0
ip add 1.1.1.1 255.255.255.0
ip ospf network point-to-point
router ospf 0
network 1.1.1.1 0.0.0.255 area 0.0.0.0)
Thanks in advance for your help,
Mark
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