Hi,
I'm configuring a pair of 6509 switches in VSS mode, and there are a number of dual homed etherchannel links (MEC) connecting to different routers, switches and servers. I plan to use a single GigabitEthernet link directly connected to both switches for fast-hello dual active detection.
I have been using "mode on" in the etherchannel configuration for all links. Are there any disadvantages to "mode on" comparing with LACP or PAgP in VSS mode?