What is an Etherchannel?

SW1#conf tEnter configuration commands, one per line. End with CNTL/Z
.SW1(config)#interface fast 0/11
SW1(config-if)#channel-group 1 mode onCreating a port-channel interface Port-channel 1
SW1(config-if)#interface fast 0/12
SW1(config-if)#channel-group 1 mode on

SW2#conf tEnter configuration commands, one per line. End with CNTL/Z.
SW2(config)#int fast 0/11
SW2(config-if)#channel-group 1 mode on
SW2(config-if)#int fast 0/12
SW2(config-if)#channel-group 1 mode on

An Etherchannel is simply a logical bundling of 2 - 8 physical connections between two Cisco switches.