[ixp1200] IXP1200 sending out a flood of packets on port 3

After booting up embedded linux on the StrongARM, and assigning MAC addresses to ports 0 through 3, a flood of packets is being sent out of port 3 of the IXP1200. No microengines are doing any processing. I am wondering if anyone else had this problem, or an idea of what it might be. Thanks, Chris