3com WX3000 User Manual

 

1-5 

Changing the system priority of a device may change the preferred device between the two parties, and 

may further change the states (selected or unselected) of the member ports of dynamic aggregation 

groups. 

 

LACP determines the selected and unselected states of the dynamic aggregation group members 

according to the port IDs on the device with the preferred device ID. When the number of members in an 

aggregation group exceeds the number of selected ports supported by the device in each group, LACP 

determines the selected and unselected states of the ports according to the port IDs. The ports with 

superior port IDs will be set to selected state and the ports with inferior port IDs will be set to unselected 

state.  

The port ID consists of two-byte port priority and two-byte port number, that is, port ID = port priority + 

port number. When two port IDs are compared, the port priorities are compared first, and the port 

numbers are compared if the port priorities are the same.  

Depending on whether or not load sharing is implemented, aggregation groups can be load-sharing or 

non-load-sharing aggregation groups. When load sharing is implemented, 

z 

For IP packets, the system will implement load-sharing based on source IP address and 

destination IP address; 

z 

For non-IP packets, the system will implement load-sharing based on source MAC address and 

destination MAC address. 

In general, the system only provides limited load-sharing aggregation resources, so the system needs 

to reasonably allocate the resources among different aggregation groups. 

The system always allocates hardware aggregation resources to the aggregation groups with higher 

priorities. When load-sharing aggregation resources are used up by existing aggregation groups, 

newly-created aggregation groups will be non-load-sharing ones. 

Load-sharing aggregation resources are allocated to aggregation groups in the following order: 

z 

An aggregation group containing special ports (such as 10GE port) which require hardware 

aggregation resources has higher priority than any aggregation group containing no special port. 

z 

A manual or static aggregation group has higher priority than a dynamic aggregation group (unless 

the latter contains special ports while the former does not). 

z 

For aggregation groups, the one that might gain higher speed if resources were allocated to it has 

higher priority than others. If the groups can gain the same speed, the one with smallest master 

port number has higher priority than other groups. 

When an aggregation group of higher priority appears, the aggregation groups of lower priorities 

release their hardware resources. For single-port aggregation groups, they can transceive packets 

normally without occupying aggregation resources