Ether Channel Configuration on Cisco Switches

EtherChannel is a port link aggregation technology or port-channel architecture used primarily on Cisco switches. It allows grouping of several physical Ethernet links to create one logical Ethernet link for the purpose of providing fault-tolerance and high-speed links between switches, routers and servers.

Let's assume we are going to create an ether channel using  fast ethernet 0/1 to 0/4

1. First Create a port channel interface with unique no
SW1(config)# interface port-channel 1

2. Select the group of intefaces or interface which need to add into port channel

SW1(config)#interface range f0/1-4 

or

SW1(config)#interface f0/1

3. Add interface to created port channel no and select the mode. auto is set as mode in given example 

active     -  The interface starts negotiations with other interfaces by sending LACP packets.

passive    - The interface responds to LACP packets that it receives, but does not start LACP packet negotiation. This setting minimizes the transmission of LACP packets.

desirable - The interface starts negotiations with other interfaces by sending PAgP packets.

auto        - The interface responds to PAgP packets it receives but does not start PAgP packet negotiation. This setting minimizes the transmission of PAgP packets. 

on           - Forces the interface into an EtherChannel without PAgP or LACP. With the on mode, a usable EtherChannel exists only when an interface group in the on mode is connected to another interface group in the on mode.

SW1(config-if-range)#channel-group 1 mode auto

4. end :)

SW1(config-if-range)#end