How should I discipline my 13 mth old DS

[spangles]

My DS2 is 13 months old and has started to hit my 4.5 yr old DS1. DS1 is being very good about this and even laughs when this happens. Should I ask DS1 to say "no smacking" and to try not to laugh or should I ignore this behaviour or should I just distract DS2 when he does this.
DS2 laughs when I tell him "no smacking" and thinks its all a game.
DS1 was always "heavy handed" with other children and I really want to avoid this sort of behaviour with DS2. any advice?

Probably wise to explain to DS1 not to laugh, so that DS2 learns its not a game.

I would be inclined to say a firm no to DS2 and then give DS1 some attention for a minute, ignoring DS2.

I absolutely sympathise.
I think that Fran is right - you have to explain to DS1 that you need to work together to stop DS2 from hitting, or he is going to start hurting people when he gets a bit bigger. So no laughing, and move out of the way so he can't be reached.
I suspect though that saying no is a complete waste of your breath, and could indeed be the attention that he is after. i would be tempted to ignore, and make sure that DS1 is working with you to try to make it less of an attractive option.
I have had similar probs with my lot and still can't work out the best way to deal with it. DS2 is now 3 so def big enough to be disciplined but at 13mths so much of what they do is just experimenting and they are seeing what their boundaries are. If he stops getting satisfaction from it then chances are he'll quit.?>