3Com Switch 8800 Advanced Software V5 Configuration Guide

72 CHAPTER 8: LINK AGGREGATION OVERVIEW
interrupted. You need to avoid the situation however as the selected/unselected
state of a port may become different after a reboot.
n
Currently, the number of the selected ports in a manual aggregation group
created on a Switch 8800 can be up to eight.
Port Configuration Considerations in manual aggregation
As mentioned above, in a manual aggregation group, only ports with
configurations consistent with those of the master port can become selected.
These configurations include port rate, duplex mode, link state and other basic
configurations described in
“Consistency Considerations for Ports in an
Aggregation Group” on page 70.
You need to maintain the basic configurations of these ports manually to ensure
consistency. As one configuration change may involve multiple ports, this can
become troublesome if you need to do that port by port. As a solution, you may
add the ports into an aggregation port group where you can make configuration
for all member ports.
When the configuration of some port in a manual aggregation group changes, the
system does not remove the aggregation as it does in a dynamic aggregation
group; instead, it re-sets the selected/unselected state of the member ports and
re-selects a master port.
Static LACP link
aggregation
Overview
In the static aggregation approach, aggregation groups are created
administratively and the system cannot automatically add or remove ports.
On the ports in the group, LACP is enabled and cannot be administratively
disabled. After the group is removed, all the member ports in up state form one or
multiple dynamic aggregations with LACP enabled.
Port states in static aggregation
In a static aggregation group, ports can be selected or unselected, where both can
receive and transmit LACPDUs but only selected ports can receive and transmit
data frames. The selected port with the lowest port number is the master port and
all others are member ports.
All member ports that cannot aggregate with the master are placed in unselected
state. These ports include those using the basic configurations different from the
master port or those located on a module different from the master port because
of hardware restriction.
Member ports in up state can be selected if they have the configuration same as
that of the master port. The number of selected ports however, is limited in a static
aggregation group. When the limit is exceeded, the local and remote systems
negotiate the state of their ports as follows:
1 Compare the actor and partner system IDs that each comprises a system LACP
priority plus a system MAC address as follow:
■ First compare the system LACP priorities. The system with lower system LACP
priority wins out.