routes in ospf not showing mask

Unanswered Question
Oct 2nd, 2008

Hi all, I have the network on one of my routers, on the other router usng ospf its showing the route to network,where as i thought is should be route to network

see below [110/2] via, 00:06:34, FastEthernet0/0

why is this not showing me route to the /24


I have this problem too.
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carl_townshend Thu, 10/02/2008 - 08:07

Hi there

the interface ip is

the statement was


but have have tried

I was told as long as you include the interface within the statement, the ip of the interface and mask get advertised.

why is the proper route not showing ?

It is on a loopback interface

John Blakley Thu, 10/02/2008 - 08:15

It's showing just the host address because that's what you're telling it with the mask. Try to change to:

network area 0 (or whatever area)

You mentioned that it's a loopback though. Others can chime in, but I think you would also want to advertise your normal network along with it.

network area 0

network area 0

Are your local ethernet interfaces in the network?


Richard Burts Thu, 10/02/2008 - 11:29


This issue has nothing to do with what mask is used in the network statement and changing the mask will have no effect on what is advertised.

The key to this issue is the mention that the interface is a loopback interface. OSPF will advertise a loopback interface as a /32 and consider it a stub host no matter what mask is configured on the interface and no matter what mask is used in the network statement. (check this with the output of show ip ospf interface) The solution to this is to configure on the loopback interface ip ospf network point-to-point. If you do this then OSPF will advertise the subnet with the configured mask.




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