3Com Baseline 2928 PWR Plus User Manual page 239

The rate of an aggregate interface is the sum of the selected member ports' rates. The duplex mode of
an aggregate interface is consistent with that of the selected member ports. Note that all selected
member ports use the same duplex mode.
For how the state of a member port is determined, refer to
aggregation mode.
LACP protocol
The Link Aggregation Control Protocol (LACP) is defined in IEEE 802.3ad. It uses link aggregation
control protocol data units (LACPDUs) for information exchange between LACP-enabled devices.
LACP is automatically enabled on interfaces in a dynamic aggregation group. For information about
dynamic aggregation groups, refer to
LACPDUs to notify the remote system (the partner) of its system LACP priority, system MAC address,
LACP port priority, port number, and operational key. Upon receiving an LACPDU, the partner
compares the received information with the information received on other interfaces to determine the
interfaces that can operate as selected interfaces. This allows the two systems to reach an agreement
on which link aggregation member ports should be placed in selected state.
Operational key
When aggregating ports, link aggregation control automatically assigns each port an operational key
based on port attributes, including the port rate, duplex mode and link state configuration.
In an aggregation group, all selected ports are assigned the same operational key.
Class-two configurations
The contents of class-two configurations are listed in
different from the aggregate interface in the class-two configurations cannot be a selected port.
Table 1-1 Class-two configurations
Type
Port isolation
VLAN
Some configurations are called class-one configurations. Such configurations, for example, MSTP,
can be configured on aggregate interfaces and member ports but are not considered during
operational key calculation. For details of MSTP configuration on member ports of link aggregation
groups or aggregate interfaces, see related sections in MSTP Configuration.
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. For details of port isolation configuration
and VLAN configuration on member ports of link aggregation groups or aggregate interfaces, see
related sections in Port Isolation Configuration and VLAN Configuration.
Dynamic aggregation
Table
Whether a port has joined an isolation group
Permitted VLAN IDs, default VLAN, link type (trunk, hybrid, or
access), ,tag mode
1-2
Static aggregation mode
mode. An LACP-enabled interface sends
1-1. In an aggregation group, a member port
Considerations
and Dynamic