ospf default-information originate

[cliff.bowles]

Greetings. I have a quick question that I haven't been able to answer in a CCO article:

When you have an OSPF ABR, and you configure it with the default-information originate command (without the "always" option) will that ABR stop injecting the default route if its own default route dies? In other words, router-A is an ABR and it has a static default to an ISP. The ABR injects a default via the default-information originate command. Let's say that the link between router-A and the ISP breaks... does router-A stop injecting the default route?

Thanks in advance!

CWB

[vladrac-ccna]

I would say yes.

You need a default route on the ABR in order to this command work without the option always

from cisco:

"Whenever you use the redistribute or the default-information router configuration command to

redistribute routes into an OSPF routing domain, the Cisco IOS software automatically becomes an

Autonomous System Boundary Router (ASBR). However, an ASBR does not, by default, generate a

default route into the OSPF routing domain. The software still must have a default route for itself before

it generates one, except when you have specified the always keyword."

HTH,

please rate all posts.

vlad

[Richard Burts]

CWB

First a clarification: as Vlad correctly points out an OSPF router with default-information originate is an ASBR not an ABR.

Then the substantive answer to your question: an OSPF router configured with default-information originate (but without the always keyword) will only advertise a default route as long as it has a valid default route. And that router will stop advertising a default route is its default route becomes invalid.

HTH

Rick

[cliff.bowles]

Thank you both for the response. That makes sense. The documentation implied but did not specifically state that the removal of the default route (by link drop or whatever means) would in turn cause the ASBR to cease injecting the default.

Thanks again!

CWB