Question

You are bundling two links between SW1 and SW2 into a Layer 2 EtherChannel. On SW1 both interfaces are configured with 'channel-group 1 mode on'. On SW2 both interfaces are configured with 'channel-group 1 mode active'. After the configuration, the port-channel does not come up and the individual interfaces show as err-disabled or independent. What is the cause of this problem?

Accepted Answer

One side uses static ('on') mode while the other uses LACP ('active'), so the channel cannot negotiate and fails to form

Answer

Both sides must use PAgP with 'desirable' mode for a Layer 2 EtherChannel to form

Answer

The port-channel interface number must be different on each switch for the bundle to negotiate

Answer

Layer 2 EtherChannels require the interfaces to be configured as trunk ports before the channel-group command is applied