OSPF Null Routes

[cafnetmatt]

I've deployed a mix of 7005 & 7010 controllers.  4 locations using IPSec to connect them and L3 GRE tunnels to be able to do OSPF.  The configuration is a full mesh.

I have it working but it's been having issues routing traffic.  I have a ticket open with TAC who is still trying to figure out what is wrong.

Anyway, my question.  In the configuration guide, there are these null routes that are put in.  Why do they do this?  I've never used something like this and the guide provides no explanation for them.

This is the URL:  http://www.arubanetworks.com/techdocs/ArubaOS_60/UserGuide/OSPF.php#XREF_44064_Sample_Topology

I've reviewing my config just in case I missed something causing these intermittent routing issues and always wondered why the null routes?

Thanks

[msabin]

I often use null routes to force a router to install a route which matches a summary or aggregate statement, I don't have Aruba OSPF experience so I can't speak to why they're using the class B summary routes, but I suspect it has something to do with managing link advertisements or summarization.