3Com Switch 8800 Advanced Software V5 Configuration Guide

Approaches to Link Aggregation 71
Approaches to Link
Aggregation
The options available for implementing link aggregation are described in the
sections entitled
“Manual Link Aggregation” on page 71 and “Static LACP link
aggregation” on page 72.
Manual Link
Aggregation
Overview
In the manual aggregation approach, aggregation groups are created
administratively and automatic port adding/removal is not available.
On the ports in a manual aggregation, LACP is disabled and cannot be
administratively enabled.
Port states in a manual aggregation
In a manual aggregation group, ports are either selected or unselected. Selected
ports can receive and transmit data frames whereas unselected ones cannot.
Among all selected ports, the one with the lowest port number is the master port
and others are member ports.
When setting the state of ports in a manual aggregation group, the system
considers the following:
■ Select a port from the ports in up state, if any, in the order of full duplex/high
speed, full duplex/low speed, half duplex/high speed, and half duplex/low
speed, with the 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. Then, place those ports in up state with the same
speed/duplex pair, link state and basic configuration in selected state and all
others in unselected state.
■ When all ports in the group are down, select the port with the lowest port
number as the master port and set all ports (including the master) in unselected
state.
■ Place the ports that cannot aggregate with the master in unselected state, for
example, as the result of hardware restriction.
Manual aggregation limits the number of selected ports in an aggregation group.
When the limit is exceeded, the system changes the state of selected ports with
greater port numbers to unselected until the number of selected ports drops
under the limit.
In addition, unless the master port should be selected, a port that joins the group
after the limit is reached will not be placed in selected state even if it should be in
normal cases. This is to prevent the ongoing service on selected ports from being
MAC address learning ■ MAC address learning capability
■ Setting of maximum number of MAC
addresses that can be learned on the port
■ Forwarding of frames with unknown
destination MAC addresses after the upper
limit of the MAC address table is reached
Table 6 Consistency considerations for ports in an aggregation
Category Considerations