Allied Telesis AT-S62 - Manual (Page 141)

AT-S62 Management Software Menus Interface User’s Guide
Section I: Basic Operations 141
Here is how this example looks in table format for the ports on the
AT-8500 Series switch.
You could, if you wanted, create separate aggregators for the different
aggregate trunks in the example above. But letting the switch make the
determination for you whenever possible can save you time later if you
physically reassign ports to a different trunk connected to another device.
LACP System Priority
It is possible for two devices interconnected by an aggregate trunk to
encounter a conflict when forming a trunk. For example, the two devices
might not support the same number of active ports in an aggregate trunk
or might not agree on which ports are to be active and which are to be in
standby.
If a conflict occurs, the devices need a mechanism for resolving the
problem, a means by which they can decide whose LACP settings are to
take precedence. That is the function of the system LACP priority value. A
hexadecimal value of from 1 to FFFF, this parameter is used whenever the
devices encounter a conflict creating a trunk. The lower the number, the
higher the priority. The settings on the device with the higher priority takes
precedence over the settings on the other device. If both devices have the
same system LACP priority value, the settings on the switch with the
lowest MAC address take precedence.
This parameter can prove useful when connecting an aggregate trunk
between an AT-8500 Series switch and another 802.3ad-compliant device
that does not have the same LACP trunking capabilities. If the other
device’s capability is less than that of the AT-8500 Series’, you should give
that device the higher priority so that its settings are used by both devices
when forming the trunk.
For example, an aggregate trunk of six links between an AT-8500 Series
switch and an 802.3ad-compliant device that supported up to four active
links at one time could possibly result in a conflict. The AT-8500 Series
switch would try to use all six links as active, since it can handle up to eight
active links in a trunk at one time, while the other device would want to use
only four ports as active. By giving the other 802.3ad device the higher
priority, the conflict would be avoided. The AT-8500 Series switch would
use only four active links because the settings on the other device would
take precedence. The other ports would be in standby mode.
Aggregator
Description Aggregator
Ports Aggregate
Trunk Ports
Aggregator 1 1-3, 12-14 1-3
12-14