Just enrolled my 11 week old rottie in puppy school. The trainer uses positive rewards only and told me to give time outs for biting that gets too aggressive. In talking with other owners of large dogs they seem to think you need to punish so pups know boundries when it comes to biting. Is it playful or aggressive? And what is the right way to go about having a well trained large dog?

I don't think it is a good idea to allow any kind of play biting. When training a puppy during play periods whenever the puppy tries to mouth or bite it is best to offer a toy that can be bit and mouthed. I've found it to be safer that way the dog learns that it just doesn't feel normal to put its mouth and teeth on your flesh or anyone else's flesh.

I agree with sunflower... puppies naturally bite and chew but they shouldn't use your fingers as a chew toy.

A method that has worked well for me is when the puppy starts play biting you remove your hand straight away say "NO" and ignore the puppy.

Another way is to remove your hand straight away, give a firm "NO" and give the puppy an alternative thing to chew on like a kong or other toy.

It depends on how the dog reacts to the training as to what method to use :)

His bite is actually getting softer with the command EASY. And of course I am reardiung him every time he gums my hand. When he gives a hard bite he gets a time out... basically ignoring him and stop laying for about a minute. The trainer stresses this is important because a dog who doesn't learn the strength of his bite can then later in life bite out of fear and do a lot of damage. Still unsure because I am hearing a lot of " you need to assert dominance"... ADVISE PLEASE!

I've never hear of the saying that if you don't teach them how hard they are biting then they will end up fear biting.
Mine bite as hard as they want on toys (usually ripping them to pieces)
As puppies we just did exactly what you are doing and they stopped biting us and started playing with their toys.

I've never really consciously asserted dominance on my dogs, they get in trouble for doing something naughty like jumping up to steal something or during toilet training, I just tell them "no" and direct them in the right direction.

Dogs are pack animals, you do need to show that you are the pack leader but most dogs learn this through simple training... during any form of training (I'll use toilet as an example) You scold the puppy and say "no" for bad behaviour and physically move the puppy to the right location to do their business. Therefore they learn that what you say, they must do!

They learn from an early age who the boss is as long as you train them :)