Ospf default route.

Unanswered Question
Aug 4th, 2008

Hi All,

A very basic question.I know ospf dont generate a defualt route unless we specify the deault information originate command. I would like to know the reason behind such behaviour. Though I have a default route and redistribute static routes to ospf process the default route doesn't appear in routing table without default originate command. Any specific reason for such behaviour?

I have this problem too.
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shrikar.dange Tue, 08/05/2008 - 00:58

Hi,

Thanks for reply. I know how to inject the default route in an ospf area. I need the explanation for this behaviour of an ospf router:

The OSPF router does not, by default, (even after redistributing static routes)generate a default route into the OSPF domain.

My question is if I am using a staically configured default route and redistributing the static routes in an ospf process, the default route will not be advertised to other ospf neighbors untill and unless I use the default information originate command. Why is it so?

regards,

shri :)

Joseph W. Doherty Tue, 08/05/2008 - 03:13

The simple reason is to allow you to determine whether you want the default route to be advertised to your routers or not. If you had a network that all destinations were known, not advertising a default would allow the gateway router to drop traffic with an unknown address without forwarding it. If you had an Internet connection, now you'll likely want your internal routers to forward traffic with unknown addresses toward it.

shrikar.dange Tue, 08/05/2008 - 21:58

Hi Joseph,

Thanks for the reply.

Ohhh....Is it that simple? :) :)

I was looking for some complicated/technical reason :)

regards,

shri

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