3Com 4200G 12-Port, Configuration Manual

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15
L
INK
A
GGREGATION
C
ONFIGURATION
Overview
Introduction to Link
Aggregation
Link aggregation means aggregating several ports together to form an aggregation
group, so as to implement outgoing/incoming load sharing among the member ports
in the group and to enhance the connection reliability.
Depending on different aggregation modes, aggregation groups fall into three types:
manual, static LACP, and dynamic LACP. Depending on whether or not load sharing is
implemented, aggregation groups can be load-sharing or non-load-sharing
aggregation groups.
For the member ports in an aggregation group, their basic configuration must be the
same. The basic configuration includes STP, QoS, VLAN, port attributes and other
associated settings.
■
STP configuration, including STP status (enabled or disabled), link attribute
(point-to-point or not), STP priority, maximum transmission speed, loop prevention
status, root protection status, edge port or not.
■
QoS configuration, including traffic limiting, priority marking, default 802.1p
priority, bandwidth assurance, congestion avoidance, traffic redirection, traffic
statistics, and so on.
■
VLAN configuration, including permitted VLANs, and default VLAN ID.
■
Port attribute configuration, including port rate, duplex mode, and link type
(Trunk, Hybrid or Access).
Introduction to LACP The purpose of link aggregation control protocol (LACP) is to implement dynamic link
aggregation and deaggregation. This protocol is based on IEEE802.3ad and uses
LACPDUs (link aggregation control protocol data units) to interact with its peer.
After LACP is enabled on a port, LACP notifies the following information of the port
to its peer by sending LACPDUs: priority and MAC address of this system, priority,
number and operation key of the port. Upon receiving the information, the peer
compares the information with the information of other ports on the peer device to
determine the ports that can be aggregated with the receiving port. In this way, the
two parties can reach an agreement in adding/removing the port to/from a dynamic
aggregation group.
Operation Key An operation key of an aggregation port is a configuration combination generated by
system depending on the configurations of the port (rate, duplex mode, other basic
configuration, and management key) when the port is aggregated.
1 The selected ports in a manual/static aggregation group must have the same
operation key.
2 The management key of an LACP-enable static aggregation port is equal to its
aggregation group ID.
3 The management key of an LACP-enable dynamic aggregation port is zero by default.