[c-nsp] How to effect a totally stubby area in IS-IS

[Jared Gillis]

Hi all,

I run an IS-IS network, and need to convert it such that it can support something akin to an OSPF totally stubby area.
In a nutshell, we have backbone routers that redundantly serve POP routers. We need the POP routers to be able to advertise local routes (loopbacks, etc), and only want them to receive defaults from the backbone. The main concern is that we don't want POP router A to learn POP router B's routes, just to follow their default to the backbone which has that information.

Our current config is that the backbone routers are L2-only, and the POP routers are L1/L2, and the result is that all routes are propagated across the entire network. In the lab, I've tried switching backbone to L1/L2 and POP routers to L1, with the same effect.

I thought I may have found the solution in IS-IS multi-area (multiple IS-IS instances on the backbone routers), and moving each POP into it's own sub-connection. This accomplishes stopping other network routes from going down to the POP router, however, routes from the POP router stay local to the directly-connected backbone router no matter what I do. There is a command for redistributing routes from one IS-IS instance to another, but it doesn't seem to work.

Does anyone have any suggestions on how to accomplish this?
Thanks!

-Jared