3Com Switch 7757, Configuration Manual

Page: 185 / 940

Overview 185
port, you cannot remove the port unless you remove the whole aggregation
group.
LACP is enabled on the member ports of static aggregation groups, and disabling
LACP on such a port will not take effect. When you remove a static aggregation
group, the system will remain the member ports of the group in LACP-enabled
state and re-aggregate the ports to form one or more dynamic LACP aggregation
groups.
Port status of static aggregation group
A port in a static aggregation group can be in one of the two states: selected or
standby. Both the selected and the standby ports can transceive LACPDUs
however, the standby ports cannot forward user packets.
n
In an aggregation group, the selected port with the minimum port number serves
as the master port of the group, and other selected ports serve as member ports
of the group.
In a static aggregation group, the system sets the ports to selected or standby
state according to the following rules:
■
The system sets the “most preferred” ports (that is, the ports take most
precedence over other ports) to selected state, and others to standby state.
Port precedence descends in the following order: full duplex/high speed, full
duplex/low speed, half duplex/high speed, half duplex/low speed.
■
The system sets the following ports to standby state: ports that are not
connected to the same peer device as the master port (selected port with the
minimum port number), and ports that are connected to the same peer device
as the master port but not in the same aggregation group as the master port.
■
The system sets the ports unable to aggregate with the master port (due to
some hardware limit, for example, cross-board aggregation unavailability) to
standby state.
■
The system sets the ports with basic port configuration different from that of
the master port to standby state.
There is a limit on the number of selected ports in an aggregation group.
Therefore, if the number of the member ports that can be set as selected ports in
an aggregation group exceeds the maximum number supported by the device, the
system will choose the ports with lower port numbers as the selected ports, and
set others as standby ports.
n
For the restriction of I/O Module types on link aggregation, refer to Table 120 and
Table 121.
Dynamic LACP
Aggregation Group
Introduction to dynamic LACP aggregation group
A dynamic LACP aggregation group is automatically created and removed by the
system. Users cannot add/remove ports to/from it. Ports can be aggregated into a
dynamic aggregation group only when they are connected to the same peer
device and have the same basic configuration (such as rate and duplex mode).