Cisco port-channel settings (link aggregation)

The main function of Port-channel in practical work is to bundle two or more ports into a virtual channel.

Interface Port-channel1
Description Port (1/0/5-6)
Switchport Trunk Encapsulation dot1q
Switchport Trunk allowed VLAN 10
Switchport mode Trunk
!
Interface Port-channel2
Description Port (1/0/7-8)
Switchport Trunk Encapsulation dot1q
Switchport Trunk allowed VLAN 10
Switchport mode Trunk
!
Interface Port-channel3
Description Port (1/0/9-10)
Switchport Trunk Encapsulation dot1q
Switchport Trunk allowed VLAN 10
Switchport mode Trunk
!
Interface Port-channel4
Description Port (1/0/11-12)
Shutdown

These are the configurations I made on the Cisco 3750, where:

Description Port (1/0/5-6) is a description of this virtual channel that tells the virtual channel to use port 1/0/5 and 6 ports

Switchport Trunk Encapsulation dot1q is a forced virtual channel using dot 1q to encapsulate packets

Switchport trunk allowed VLAN 10 is a VLAN that forces virtual channels to pass through, in this case only VLAN10 can pass through this channel

Switchport mode trunk is mandatory for triuk modes

The specific commands are as follows:

3750-route#configure Terminal

3750-route (config) #interface Port-channel 1
3750-route (config-if) #switchport mode trunk
3750-route (config-if) #switchport trunk Encapsulation dot1q
3750-route (config-if) #switchport trunk allowed VLAN 10
3750-route (config-if) #description xxxxxx

After you create Port-channel 1, you also need to configure it on the appropriate port

Interface GIGABITETHERNET1/0/5
Description Port-channel-1
Switchport Trunk Encapsulation dot1q
Switchport mode Trunk
Channel-group 1 mode on
!
Interface GIGABITETHERNET1/0/6
Description Port-channel-1
Switchport Trunk Encapsulation dot1q
Switchport mode Trunk
Channel-group 1 mode on

The last command is especially important here.

Channel-group 1 mode on is Port-channel 1 can call this port, in other words: This port belongs to Port-channel 1

The specific commands are as follows:

3750-route#configure Terminal

3750-route (config) #interface range gigabitethernet 1/0/5-6
3750-route (config-if) #switchport mode trunk
3750-route (config-if) #switchport trunk Encapsulation dot1q
3750-route (config-if) #description xxxxxx
3750-route (config-if) #channel-group 1 mode on

Cisco port-channel settings (link aggregation)