From: prashant shukla (shukla_cisco@yahoo.co.in)
Date: Sun Jan 07 2007 - 06:51:34 ART
Hey Ben,
In OSPF , its very imperative that we need to advertise only specific interface in specific areas.
By keeping the wildcard to be 0.0.0.0 we mean only that particular interface to be advertised in specific areas.
E.g i have 2 Serial interfaces with IPs,
S0----192.168.1.8 255.255.255.240
S1----192.168.1.16 255.255.255.240.
Now if we want serial 0 to be in Area 0 and serial 1 to be in Area 1, we need to configure:
router ospf 1
network 192.168.1.8 0.0.0.0 area 0
network 192.168.1.16 0.0.0.0 area 1
The Exact match wildcard shall place S0 and S1 in their respective areas.
But if we configure :
192.168.1.0 0.0.0.255 area 0 .
this means ALL 192.168.1.X will be in area 0 and not the way we want.
So its Always advisable to go for exact match than a class full match.
HTH :-)
Shukla.
Ben Holko <ben.holko@datacom.com.au> wrote: going through the solutions guide for v4 of the sample lab, I'm wondering why all the ospf/eigrp network statements have a wildcard mask of 0.0.0.0
For the loopbacks I can see this (because the question asks to advertise the loopback INTERFACE address not the NETWORK address), but for the physical interface subnets they are al /24, so why aren't we saying 0.0.0.255?
Ben Holko
CISSP (ISC)2
Networking Team Leader
Datacom Systems
Ph: +61 3 9626 9600
Fax: +61 3 9626 9699
ben.holko@datacom.com.au
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