Link Aggregation Modes - H3C S5120-SI Series Operation Manual

Some configurations are called class-one configurations. Such configurations, for example, MSTP,
can be configured on aggregate interfaces and member ports but will not affect the select state of
link aggregation member ports.
The change of a class-two configuration setting may affect the select state of link aggregation
member ports and thus the ongoing service. To prevent unconsidered change, a message warning
of the hazard will be displayed when you attempt to change a class-two setting, upon which you
can decide whether to continue your change operation.

Link Aggregation Modes

Depending on the link aggregation procedure, link aggregation operates in one of the following two
modes:
Static aggregation mode
Dynamic aggregation mode
Static aggregation mode
LACP is disabled on the member ports in a static aggregation group. In a static aggregation group, the
system sets a port to selected or unselected state by the following rules:
Select a port as the reference port from the ports that are in up state and with the same class-two
configurations as the corresponding aggregate interface. These ports are selected in the order of
full duplex/high speed, full duplex/low speed, half duplex/high speed, and half duplex/low speed,
with full duplex/high speed being the most preferred. If two ports with the same duplex mode/speed
pair are present, the one with the lower port number wins out.
Consider the ports in up state with the same port attributes and class-two configurations as the
reference port as candidate selected ports, and set all others in the unselected state.
Static aggregation limits the number of selected ports in an aggregation group. When the number
of the candidate selected ports is under the limit, all the candidate selected ports become selected
ports. When the limit is exceeded, set the candidate selected ports with smaller port numbers in the
selected state and those with greater port numbers in the unselected state.
If all the member ports are down, set their states to unselected.
Set the ports that cannot aggregate with the reference port to the unselected state.
A port that joins the aggregation group after the limit on the number of selected ports has been reached
will not be placed in the selected state even if it should be in normal cases. This can prevent the ongoing
traffic on the current selected ports from being interrupted. You should avoid the situation however, as
this may cause the selected/unselected state of a port to change after a reboot.
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