I was recently preparing for a ccnp-switch exam.
I came on the topic etherchannel and wanted to document the steps for a layer 2 and layer 3 etherchannel.
The steps which need to be taken are based on the LACP(open standard) protocol.
Layer 2 Etherchannel
1. Go to configure mode and select the interfaces to configure.
example: int range fa 0/1 – 2
Make sure that the interfaces are configured as a trunk or an access interface.
switchport trunk encapsulation dot1q (*optional. Only recommended when the swouter supports isl and dot1q.)
switchport mode trunk
switchport mode access
switchport access vlan *
2. Prepare the interfaces to make an etherchannel
example: channel-protocol Lacp
3. Create the Port-channel (aka etherchannel)
example: channel-group 1 mode active
While executing the last command a virtual interface will be created.
Verify it the interfaces or not administratively shutdown. otherwise go to the pfysical interfaces and type no shut.
Create the same config on the other switch. The interfaces may be changed. It depends on how the switches are linked together.
when the configuration is done the config can be verified with:
sh eth sum
S stands for layer 2
U stands for in use
Layer 3 Etherchannel
1. Before a layer 3 etherchannel can be created it is important to enable ip routing in the global configuration mode (conf t). (layer 3 swouter is required )
2. disable switching functionality on the interface
int range fa 0/1 – 2
3. Prepare the L3 etherchannel.
Channel-Group 1 mode active
The interface Po1 is created..
4. Give the interface a IP address
ip address 10.0.1.1 255.255.255.0
Description L3 Eth to DLS2 Po1
5. Verify the etherchannel
sh eth sum
if it shows RU = good
otherwise not good
R = L3
U = in use.