How static link aggregation works
Choosing a reference port
When setting the aggregation states of the ports in an aggregation group, the system automatically chooses a member port as the reference port. A Selected port must have the same operational key and attribute configurations as the reference port.
The system chooses a reference port from the member ports in up state.
The candidate reference ports are organized into different priority levels following these rules:
In descending order of port priority.
Full duplex.
In descending order of speed.
Half duplex.
In descending order of speed.
From the candidate ports with the same attribute configurations as the aggregate interface, the one with the highest priority level is chosen as the reference port.
If multiple ports have the same priority level, the port that has been Selected (if any) is chosen. If multiple ports with the same priority level have been Selected, the one with the smallest port number is chosen.
If multiple ports have the same priority level and none of them has been Selected, the port with the smallest port number is chosen.
Setting the aggregation state of each member port
After the reference port is chosen, the system sets the aggregation state of each member port in the static aggregation group.
Figure 3: Setting the aggregation state of a member port in a static aggregation group
After the limit on Selected ports is reached, the aggregation state of a new member port is set as follows:
The port is placed in Unselected state if the port has the same priority as all existing Selected ports. This mechanism prevents traffic interruption on the existing Selected ports. A device reboot can cause the device to recalculate the aggregation states of member ports.
The port is placed in Selected state if the following conditions are met:
The existing Selected ports have different port priorities, and the port has a higher port priority than a minimum of one Selected port.
The port has the same attribute configurations as the aggregate interface.
Any operational key or attribute configuration change might affect the aggregation states of link aggregation member ports.