routes in ospf not showing mask

Unanswered Question
Oct 2nd, 2008
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Hi all, I have the 10.116.1.0/24 network on one of my routers, on the other router usng ospf its showing the route to network 10.116.1.1,where as i thought is should be route to network 10.116.1.0/24


see below


10.116.1.1 [110/2] via 192.168.2.1, 00:06:34, FastEthernet0/0


why is this not showing me route to the /24


cheers

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John Blakley Thu, 10/02/2008 - 07:39
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What does your ospf statements look like on the other end?


--John

carl_townshend Thu, 10/02/2008 - 08:07
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Hi there


the interface ip is 10.116.1.1/24


the statement was

network 10.116.1.1 0.0.0.0


but have have tried 10.116.1.0 0.0.0.255


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
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It's showing just the host address because that's what you're telling it with the 0.0.0.0 mask. Try to change to:


network 10.116.1.0 0.0.0.255 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 10.116.1.1 0.0.0.0 area 0

network 192.168.0.0 0.0.0.255 area 0


Are your local ethernet interfaces in the 10.116.1.0/24 network?


--John

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


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.


HTH


Rick

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