"Normal" traffic is unique to every network. I would recommend doing some port monitoring, install a software such as wireshark, and then capture the data for a minute, stop it, then look at what type of traffic it is, where the source and destinations are etc.

If you just connect to a normal port, and turn on wireshark you will see all of the unknown unicast, multicast and braodcast traffic, if you span one of your trunks you will get a lot more information.

HTH,

Craig