H3C Technologies H3C WX3000E Series Wireless Switches - Manual (Page 242)

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• Static aggregation limits the number of Selected ports in an aggregation group. When the upper
limit is not reached, all the candidate selected ports become Selected ports. When the upper limit
is exceeded, the system sets the candidate selected ports with larger port numbers to Unselected
state to keep the number of Selected ports in the correct range.
• If all member ports are down, the system sets their states to Unselected.
• The system sets the ports that cannot aggregate with the reference port due to hardware constraints
to the Unselected state. An example of hardware constraints is inter-board aggregation restriction.
When the number of Selected ports reaches the upper limit, a port joining the aggregation group will not
be placed in Selected state. This can prevent the ongoing traffic on the current Selected ports from being
interrupted. However, you should avoid the situation because this might cause the Selected/Unselected
state of a port to change after a reboot.
Dynamic aggregation mode
LACP is enabled on member ports in a dynamic aggregation group.
In a dynamic aggregation group, member ports process LACPDUs depending on their states:
• A Selected port can receive and transmit LACPDUs.
• An Unselected port can receive and send LACPDUs only when it is up and has the same
configurations as the aggregate interface.
In a dynamic aggregation group, the port state is set by the following rules:
• The local system (the actor) negotiates with the remote system (the partner) based on port IDs on the
end that has the preferred system ID to determine the port state:
a. The system compares the system ID (containing the system LACP priority and the system MAC
address) of the actor with that of the partner. The system with the lower LACP priority wins. If
they are the same, the system with the smaller MAC address wins.
b. The system compares the port IDs of the ports on the system with the smaller system ID. A port
ID contains a port LACP priority and a port number. The port with the lower LACP priority wins.
If two ports have the same LACP priority, the port with the smaller port number is selected as the
reference port.
c. A port is set as a candidate selected port when it meets the following conditions. Otherwise,
the system sets the port to the Unselected state.
− The port is up and has the same port attributes and class-two configuration as the reference
port.
− The peer port has the same port attributes and class-two configurations as the peer port of
the reference port.
• Dynamic aggregation limits the number of Selected ports in an aggregation group. When the
upper limit is not reached, all the candidate selected ports are set to Selected state. When the upper
limit is exceeded, the system sets the candidate selected ports with larger port numbers to
Unselected state to keep the number of Selected ports in the correct range. At the same time, the
peer device, being aware of the changes, also changes the state of its ports.
• The system sets the ports that cannot aggregate with the reference port due to hardware constraints
to the Unselected state. An example of hardware constraints is inter-board aggregation restriction.
Guidelines
The following guidelines apply to static and dynamic aggregation modes:
• The maximum number of Selected ports allowed in an aggregation group depends on the device
model.