We in the final steps of a fork-lift upgrade going from sup2 catos to sup720 IOS. Here's the issue we have been working under every tight outage windows, so we swung half the links over onto to the new pair of 6k, but left one of the links shutdown just in case we needed to fall back to the old system. In our new design the ports are trunked links to the core. I assumed that when we plugged in the second link and turned up the interface that it would act similarly to etherchannel and that the port would come up without causing STP convergence, thus not "needing" an outage window. Well we tried it last night and that wasn't the case, plugged the second link in and sure enough, convergence. Could some one explain why with trunked links it did this?