3750 stack and etherchanneling doesn't work

[bbravo]

I was trying to enable port channeling on 2 ports on a 3-stack of 3750 switches uplinked to a cat 6509, everytime I added the second port to the port-channel group the switch was putting both ports into error disable mode, on the 6509 both uplinks are part on same channel group.

The ports on the 3750 were in g1/0/49 and g3/0/49. By the way, each port that was going to be added to the channel group was at a different physical 3750, I know the 3750 stack acts a single switch so I saw no problems doing port chaneling on ports located on different physical switches...Would anyone have an idea why this didn't work or had similar experience? Thanks!

[Pavel Bykov]

While C3750 platform supports cross-stack etherchannel, not all IOS support protocols. Only IOS 12.2(25)SEC and newer support a protocol on etherchannel. See:

http://www.cisco.com/en/US/customer/products/hw/switches/ps5023/products_configuration_example09186a00806cb982.shtml

Otherwise, you have to define it, and it will be in constant on mode. Were your interfaces clean when you created etherchannel (e.g. using "default interface gi X/X/X" command) ?

I'd try creating wtherchannel without protocol command, and than with protocol command, if the first one didn't work.

My cross-stack over 2 switches in 4-switch stack worked ok between c6506 and c3750.

[bbravo]

Thanks for your response, I'm running 12.2(35)SE and running MODE ON at both ends, not sure why this failed.

[bmath]

It works for me with crostacking I am using ver 12.2.25r. If the channel is going down make sure both ends are configures properly.

[w-sims]

Make sure you turn spanning-tree off on both the 6509 and the 3750 stack ports.