Like has been said, what has been advised will work if you be consistant and give it time. My pup is 12 weeks old today and he still bites and nips when he gets exctied as does at least one of his litter mates! On the other hand the other pup has never ever biten or nipped.

Some dogs will take longer to learn than others, in the wild they would get away with this behaviour until they are upto 16 weeks old before the adults would start putting them in their place.

Rottweilers are no more likely to be aggressive than any other breed.