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OSPF Route Summerization

Why do we advertise interface IP address when we are configuring OSPF route summerization.

Thanks in advance

Chandra

1 ACCEPTED SOLUTION

Accepted Solutions

Re: OSPF Route Summerization

In fact, you could do either. The network command looks for all interfaces that have addresses falling inside the specified range, and enables OSPF on them.

So, if you have an interface that has the address 192.168.42.1/28, you could do network 192.168.42.1 0.0.0.0, or you could do network 192.168.42.0 0.0.0.15. Either would work. So would network 192.168.42.0 0.0.0.255, because the single address on the interface falls within the specified range.

Now, supoose you have two interfaces, on 192.168.42.1/28 and 192.168.42.17/28. You could enable both of these at the same time with network 192.168.42.0 0.0.0.31. Or you could have two separate network commands, one to pull in each interface.

If you have two network commands, and an interface that is covered by both, then the first one takes precedence.

Does that help?

Kevin Dorrell

Luxembourg

6 REPLIES

Re: OSPF Route Summerization

HI

Do u mean how to do summarization in ospf ?

if u then u have to use the area range command under ur ospf process like this

router ospf 2

network

area range summarized address>

Thanks

Mahmood

New Member

Re: OSPF Route Summerization

Thanks for the reply, But I meant to say when we are configuring OSPF route summerization

network

is it network address or interface address?

thanks in advance

Re: OSPF Route Summerization

HI

For summarization u need not use wildcard mask.

Wildcard mask is used when u r advertising a particular network in the OSPF process.

Its the network address which u have calculated doing summarization and the mask is also the summarized mask.

Thanks

Mahmood

Re: OSPF Route Summerization

In fact, you could do either. The network command looks for all interfaces that have addresses falling inside the specified range, and enables OSPF on them.

So, if you have an interface that has the address 192.168.42.1/28, you could do network 192.168.42.1 0.0.0.0, or you could do network 192.168.42.0 0.0.0.15. Either would work. So would network 192.168.42.0 0.0.0.255, because the single address on the interface falls within the specified range.

Now, supoose you have two interfaces, on 192.168.42.1/28 and 192.168.42.17/28. You could enable both of these at the same time with network 192.168.42.0 0.0.0.31. Or you could have two separate network commands, one to pull in each interface.

If you have two network commands, and an interface that is covered by both, then the first one takes precedence.

Does that help?

Kevin Dorrell

Luxembourg

New Member

Re: OSPF Route Summerization

Yes, Thanks

New Member

Re: OSPF Route Summerization

So, if you have an interface that has the address 192.168.42.1/28, you could do network 192.168.42.0 0.0.0.15. and ios automatically put corrrect wildcard mask in configuration in above case it will be

netork 192.168.42.0 0.0.0.15 area x

HTH

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