How Dynamic Link Aggregation Works - H3C S7500E-X Configuration Manual

How dynamic link aggregation works

Choosing a reference port
The system chooses a reference port from the member ports that are in up state and have the same
attribute configurations as the aggregate interface. A Selected port must have the same operational
key and attribute configurations as the reference port.
The local system (the actor) and the peer system (the partner) negotiate a reference port by using
the following workflow:
The two systems compare their system IDs to determine the system with the smaller system ID.
1.
A system ID contains the system LACP priority and the system MAC address.
a. The two systems compare their LACP priority values.
The lower the LACP priority, the smaller the system ID. If LACP priority values are the same,
the two systems proceed to step b.
b. The two systems compare their MAC addresses.
The lower the MAC address, the smaller the system ID.
The system with the smaller system ID chooses the port with the smallest port ID as the
2.
reference port.
A port ID contains a port priority and a port number. The lower the port priority, the smaller the
port ID.
a. The system chooses the port with the lowest priority value as the reference port.
If ports have the same priority, the system proceeds to step b.
b. The system compares their port numbers.
The smaller the port number, the smaller the port ID.
The port with the smallest port number and the same attribute configurations as the
aggregate interface is chosen as the reference port.
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.
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