I think I know the answer to this, but I want to make sure. I'm configuring etherchannel between a 3550 and a Cat5K with an RSM. A layer 2 etherchannel works fine. I then went into the 3550 and set 'no switchport' on the physical interfaces and the port channel logical interface. I also put an IP on the port channel interface. I went into the RSM config on the Cat5K and found a port channel interface was available there. But, the etherchannel won't bundle with the 3550 set for a routed port etherchannel. I get 'incompatible' messages on the 3550. And the port channel interface on the 5K won't enable. I'm guessing that you can't have routed ports on a 5K.
Thanks in advance,
Mike