What is the algorithm used to distribute traffic between the ports of an etherchannel on the 3550? We are using the default distribution method of source-mac. Is there an IOS command I can use to see which port the traffic is using?

I am having a problem with spanning tree protocol. Our root bridge is a 6500 running IOS verison 12.1.The 6500 is running spanning tree mode PVST+. According to the doumentation I have found the switch should only send spanning tree BPDUs untagged ...