EtherChannel - LACP System ID
When using Link Aggregation Control Protocol (LACP) to create an EtherChannel, each switch obtains an LACP system ID. This ID is composed of the LACP system priority and the MAC address of the switch.
To view the LACP system ID, use the following command:
SW2#show lacp sys-id 32768, 5254.0018.8000
The switch with the lowest LACP System ID is responsible for making decisions about which ports actively participate in EtherChannel. This switch is often referred to as the "master" switch, although this is not an official term.
To determine which device has the lowest system priority when you have access to only one device, you can use the show lacp neighbor command. This command provides information about the remote device's priority. For example:
SW2#show lacp neighbor Flags: S - Device is requesting Slow LACPDUs F - Device is requesting Fast LACPDUs A - Device is in Active mode P - Device is in Passive mode Channel group 1 neighbors Partner's information: LACP port Admin Oper Port Port Port Flags Priority Dev ID Age key Key Number State Gi0/1 SA 32768 5254.0005.8000 23s 0x0 0x1 0x2 0x3D Gi0/2 SA 32768 5254.0005.8000 17s 0x0 0x1 0x3 0x3D
If the system priorities are the same, the device with the lowest MAC address will be the decision-maker for establishing the aggregation.
Links
https://forum.networklessons.com/t/troubleshooting-etherchannel/1186/28?u=lagapidis