I’ve already described the problems you’re facing when running IS-IS over partially meshed Frame Relay and provided sample working configurations. To conclude this topic, I’ve also written a “technical solution” document that describes the symptoms, verification steps and the necessary configuration changes.
Ivan Pepelnjak, CCIE#1354, is the chief technology advisor for NIL Data Communications. He has been designing and implementing large-scale data communications networks as well as teaching and writing books about advanced technologies since 1990. See his full profile, contact him or follow @ioshints on Twitter.