Interesting indeed , ODR is often overlooked as a simple way of stub routing. Anyway, about your question; my test scenario did have R5 connected as OSPF nssa. With regards to ODR this doesn’t change a thing as ODR is not dependant upon OSPF, it just advertises a default route to the (ODR) stub router even if itself doesn’t have a default route. The curious thing to me was whether ODR was capable of advertising anything other than a default-route, as shown it can’t; there’s no need for more than the default for a stub router.

Which in turn bring me to the most likely reason that ODR isn’t normally used: If the stub router only has one route out (default-route) then why use ODR when you can use a static route and be independent from CDP. The answer I suppose would be that the stub router does advertise it’s routes and as such negates the need for a fully fledged routing protocol like RIP/EIGRP/OSPF or BGP.

I’m just thinking back to the ISP CPE considerations I had to make when at Easynet. Most prominently preventing us from using ODR was the lack of support of CDP over ATM. Though I seem to recall something about Cisco supporting that now, not sure if the non-cisco dslams etc. in the path would have. Pondering this a little longer I’m curious how to limit ODR route advertisement from the stub router, the CPE in case of (single homed) ISP terminology. I suppose this would be completely up to the PE, would this be controllable via Radius via av-pairs? Hmmm, will have to see if I can test that sometime somewhere…

Thank you for your post, admittedly I’ve not been very active here lately. Which will change soon as I really should get back to my studies soon… The matter of fact is that life has kinda claimed back most of my non work time after moving to the UK in January. Good to know the info here is still read and appreciated.

Djerk

Thnx