Configure EtherChannel

In this post I will configure 2 ports on 2 switches to be an EtherChannel. This effectively bundles the lines to increase bandwidth and allows any link in the bundle to fail without affecting service.

The diagram below shows the layout of the switches.




Before starting I make sure all interfaces that I will be configuring for EtherChannel have no configuration and are in the same VLAN.

I use the following commands to configure EtherChannel on the switches.

switch1#conf t
Enter configuration commands, one per line. End with CNTL/Z.
switch1(config)#interface fastEthernet 0/1 
switch1(config-if)#channel-group 5 mode desirable 
Creating a port-channel interface Port-channel 5 
switch1(config-if)#exit
switch1(config)#interface fastEthernet 0/24 
switch1(config-if)#channel-group 5 mode desirable 
Creating a port-channel interface Port-channel 5 
switch1(config-if)#end


switch2#conf t
Enter configuration commands, one per line. End with CNTL/Z.
switch2(config)#interface fastEthernet 0/1 
switch2(config-if)#channel-group 5 mode desirable 
Creating a port-channel interface Port-channel 5 
switch2(config-if)#exit
switch2(config)#interface fastEthernet 0/24 
switch2(config-if)#channel-group 5 mode desirable 
Creating a port-channel interface Port-channel 5 
switch2(config-if)#end






I verify the configuration by checking the running config.

switch2#sh run
Building configuration...

Current configuration : 2447 bytes
!
------cut------
!
interface Port-channel5
no ip address
flowcontrol send off
!
interface FastEthernet0/1
no ip address
channel-group 5 mode desirable
!
-----cut--------
!
interface FastEthernet0/24
no ip address
channel-group 5 mode desirable


When I ping the remote switch and disconnect a cable I have no packet loss.

I also use the following useful show command to view EtherChannel information.

switch1#sh etherchannel summary 
Flags: D - down P - in port-channel
I - stand-alone s - suspended
H - Hot-standby (LACP only)
R - Layer3 S - Layer2
u - unsuitable for bundling
U - in use f - failed to allocate aggregator

d - default port
Number of channel-groups in use: 1
Number of aggregators: 1

Group Port-channel Protocol Ports
------+-------------+-----------+-----------------------------------------------
5 Po5(SU) PAgP Fa0/1(Pd) Fa0/24(P)