3Com 4200G 12-Port Configuration Manual page 90

76 C 15: L A
HAPTER INK
Manual Aggregation
Group
C
GGREGATION ONFIGURATION
4 The member ports in a dynamic aggregation group must have the same operation
key.
Introduction to manual aggregation group
A manual aggregation group is manually created. All its member ports are manually
added and can be manually removed (it inhibits the system from automatically
adding/removing ports to/from it). Each manual aggregation group must contain at
least one port. When a manual aggregation group contains only one port, you cannot
remove the port unless you remove the whole aggregation group.
LACP is disabled on the member ports of manual aggregation groups, and enabling
LACP on such a port will not take effect.
Port status in manual aggregation group
A port in a manual aggregation group can be in one of the two states: selected or
unselected. In a manual aggregation group, the selected ports can transceive user
service packets, but the unselected ports cannot.
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 manual aggregation group, the system sets the ports to selected or unselected
state by 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 unselected 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 ports unable to aggregate with the master port (due to some
■
hardware limit, for example, cross-board aggregation unavailability) to unselected
state.
The system sets the ports with port attribute configuration (rate, duplex mode,
■
and link type) different from that of the master port to unselected 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 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 unselected
ports.
Requirements on ports for manual aggregation
Generally, there is no limit on the rate and duplex mode of the port you want to add
to a manual aggregation group, even if it is an initially DOWN port.
In a manual aggregation group, the system never performs deaggregation and all the
ports in the group keep in their current working states, even when the rate and
duplex mode of a member port change. But, if the rate of the master port decreases
or the duplex mode of the master port changes, packets may be lost during packet
forwarding on the master port.