I have some odd trouble with GEtherchannels
The setup is like this:
C4006-c4003 is a 2port trunked GEC. Traffic of Hosts that are connected to those switches is fine.
C4003-Juniper(m320) is a 2port trunked GEC, too. Now, Traffic between the juniper and *some* hosts connected to the C4006 gets mulitiplicated randomly, reproducable, but not determinable. Its reproducable with ping, which then tells "DUP!".
Everytime the Channel is touched, the set of hosts on the C4006 which show the phenomen changes.
Disabling the Channel C4003-Juniper makes that problem disappear.