How dynamic link aggregation groups are built

Choosing a reference port

The system chooses a reference port from the member ports in up state. A selected port must have the same operational key and attribute configurations as the reference port.

The process by which the local system (the actor) and the peer system (the partner) negotiate a reference port occurs as follows:

  1. The two systems determine the system with the smaller system ID.

    A system ID contains the system LACP priority and the system MAC address.

    1. The two systems compare their LACP priority values.

      The lower the LACP priority, the smaller the system ID. If the LACP priority values are the same, the two systems proceed to step b.

    2. The two systems compare their MAC addresses.

      The lower the MAC address, the smaller the system ID.

  2. The system with the smaller system ID chooses the first operationally up port as the reference port.

    A port ID contains a port priority and a port number. The lower the port priority, the smaller the port ID.

Setting the aggregation state of each member port

After the reference port is chosen, the system with the smaller system ID sets the state of each member port on its side.

The system with the greater system ID can detect the aggregation state changes on the peer system. The system with the greater system ID sets the aggregation state of local member ports the same as their peer ports.

When you aggregate interfaces in dynamic mode, follow these guidelines:

  • A dynamic link aggregation group chooses only full-duplex ports as the selected ports.

  • For stable aggregation and service continuity, do not change the operational key or attribute configurations on any member port.