I wouldn't suggest advising you child to tell a teacher, because if it comes to blows, the school, in their infinite wisdom, may look at the situation and determine that you child was "plotting" to injure another student and that's not good these days....yeah, this really happened, thank God it wasn't my kid on this one.
BTW, some schools don't suspend for just 3 days, a lot of schools have a 10 day minimum suspension.
I disagree with the not telling authorities. I would prefer my kids tell the teacher and principal once or twice, that way when SHTF i can rub the teacher's noses in the fact that my child was being bullied and systematically denied protection when he went about it the "right" way. If its a push then my kid better just sit tight but if its a full out punch or something of that nature then they will have full authorization to unleash a can of whoop ass. And i prefer for there to witnesses as well like in this situation to back my kids story and spread the word so it could be the first and last time.