Hello
Try to log these packets onto a syslog and see the source IP addresses. These can be some kind of Dos attacks... you need to analyse this traffic using some kind of an intrusion detection box.
Best thing is to block all unnecessary traffic on the perimeter router using access control lists. After that , include an IPS appliance which will monitor and block all kinds of attacks and vulnarabilities. YOu can probably look for an IPS 4215 or 4240. Doing this , you will maximise the security on your network.
HOpe this helps.. rate replies if found useful..
Raj