Hi, I think I'm still missing something basic about the feedback loop caused by rip not installing a route to Null0. I understand how the route to Null0 stops the loop, but I'm not really sure why there should be one in the first place. In the example when R4 sends out it's summary route it lists a metric of 2. When it gets the summary back from the frame relay link to R5 it sees a metric of 3. Even if it gets into the RIP database, shouldn't the higher metric prevent it from being installed into routing table?
Also, while the loop is occuring, I keep seeing debuging messages saying "network 30.0.0.0 is now variably masked" after it recieves the route from R5. Why is this when the route it recieves is a /14 which is the same as the route it already has in its routing table?
Thanks for this new version! If the Beta is giving me such headaches, I can't wait to see what the full release is going to be like! 
Dave