To configure LACP on a Cisco switch

 To configure LACP on a Cisco switch, you need to first create a port-channel interface, then specify the LACP mode, and finally assign the physical interfaces to the port-channel. The main commands for LACP configuration are interface port-channel, channel-group, and lacp. You'll also need to ensure that the LACP rate and system priority are properly configured. 

1. Create a Port-Channel Interface: 

Code

   interface port-channel <channel-number>

(e.g., interface port-channel 1) 

2. Configure the Channel Group with LACP Mode: 

Code

   channel-group <channel-number> mode {active | passive}

(e.g., channel-group 1 mode active) 

• active: Initiates LACP negotiation.
• passive: Responds to LACP negotiation, but does not initiate it.

3. Configure LACP Parameters (Optional): 

• LACP Rate: Controls how often LACP control packets are sent. 

Code

      lacp rate {fast | normal}

(e.g., lacp rate fast) 

• LACP Port Priority: Sets the priority for individual ports within the LACP group.

Code

      lacp port-priority <priority>

(e.g., lacp port-priority 100) 

• LACP System Priority: Sets the system-wide priority for the switch.

Code

      lacp system-priority <priority>

(e.g., lacp system-priority 1) 

• LACP Maximum Bundle: Specifies the maximum number of active links in the LACP bundle.

Code

      lacp max-bundle <max-bundle-number>

(e.g., lacp max-bundle 3) 

4. Assign Physical Interfaces to the Port-Channel: 

• Go to the configuration of the physical interface (e.g., interface GigabitEthernet 0/1).
• Use the channel-group command to assign it to the port-channel.
• Exit the interface configuration mode to return to the global configuration. 

Example:

Code

Router# configure terminal
Enter configuration commands, ending with CTRL-Z or END
Router(config)# interface port-channel 1
Router(config-if)# no shutdown
Router(config-if)# channel-group 1 mode active
Router(config-if)# lacp rate fast
Router(config-if)# exit
Router(config)# interface GigabitEthernet 0/1
Router(config-if)# no shutdown
Router(config-if)# channel-group 1 mode active
Router(config-if)# exit
Router(config)# interface GigabitEthernet 0/2
Router(config-if)# no shutdown
Router(config-if)# channel-group 1 mode active
Router(config-if)# exit
Router(config)# end

Verification:

• show interfaces port-channel <channel-number>: Shows the status of the port-channel interface.
• show lacp : Shows the LACP configuration and status.
• show lacp summary: Shows a summary of LACP configurations on the switch.
• show lacp detail: Shows the LACP configuration and status for all the interfaces.