Manual EtherChannel Configuration in Cisco Switches Using Channel mode on

EtherChannel is a port link aggregation technology developed by Cisco, which provides fault-tolerant high-speed links between Switches, Routers, and Servers.

EtherChannel technology allows multiple physical Ethernet links (Fast EtherNet or Gigabit Ethernet) to combine into one logical channel.

There are two protocols used for negotiating EtherChannel and Link Aggregation. We can configure EtherChannel in three ways in Cisco Switches.

1. Port Aggregation Protocol (PAgP) - Cisco Proprietary protocol
2. IEEE Link Aggregation Control Protocol (LACP) - Industry Standard
3. Manual Etherchannel Configuration - Without using any negotiation protocol listed above

EtherChannel configured manually using "on" does not exchange any EtherChannel negotiation frames. If not configured properly, more chances of forming loops are there this mode, compared with using EtherChannel negotiation protocols like Port Aggregation Protocol (PAgP) and IEEE Link Aggregation Control Protocol (LACP).

Follow these steps to configure EtherChannel manually using "on" in Cisco Switches. The ports which are going to be in EtherChannel must be in the shutdown state while configuring the EtherChannel to prevent loops and other related problems.

Switch omnisecu.com.SW1

omnisecu.com.SW1>
omnisecu.com.SW1>enable
omnisecu.com.SW1#configure terminal 
Enter configuration commands, one per line.  End with CNTL/Z.
omnisecu.com.SW1(config)#interface range gigabitEthernet 0/1 - 2
omnisecu.com.SW1(config-if-range)#channel-group 1 mode on 
omnisecu.com.SW1(config-if-range)#exit
omnisecu.com.SW1(config)#exit
omnisecu.com.SW1#

Switch omnisecu.com.SW2

omnisecu.com.SW2>enable 
omnisecu.com.SW2#configure terminal
Enter configuration commands, one per line.  End with CNTL/Z.
omnisecu.com.SW2(config)#interface range gigabitEthernet 0/1 - 2
omnisecu.com.SW2(config-if-range)#channel-group 1 mode on
omnisecu.com.SW2(config-if-range)#exit
omnisecu.com.SW2(config)#exit
omnisecu.com.SW2#