Link Aggregation Modes - 3Com S7906E Configuration Manual

Link Aggregation Modes

Depending on the link aggregation procedure, link aggregation operates in one of the following two
modes:
Static aggregation mode.
configured, the selected state of the member ports will not be affected by their peers. But on the
other hand, because the selected state of the member ports cannot change according that of the
peers, static aggregation is not flexible.
Dynamic aggregation mode.
ports can adjust according to that of the peers. In other words, the selected state of the member
ports is easily affected by the network environment, which makes dynamic aggregation instable.
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 (port rate, duplex mode, and link state
configuration) 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.
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.
Dynamic aggregation mode
LACP is enabled on member ports in a dynamic aggregation group.
In a dynamic aggregation group,
A selected port can receive and transmit LACPDUs.
An unselected port can receive and send LACPDUs only if it is up and with the same configurations
as those on the aggregate interface.
In a dynamic aggregation group, the system sets the ports to selected or unselected state in the
following steps: The local system (the actor) negotiates with the remote system (the partner) to
Static aggregation is stable. After a static link aggregation group is
In a dynamic link aggregation group, the selected state of the member
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