Allied Telesis AT-S63 - Manual (Page 153)

AT-S63 Management Software Menus Interface User’s Guide
Section I: Basic Features 153
Here is how this example looks in table format.
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 saves 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 they form the 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 does occur, the two 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
take 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-9400 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-9400 Series switch, 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-9400 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-9400 Series
switch would try to use all six links as active, because 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 is avoided because the AT-9400 Series switch
would use only four active links, as directed by the other 802.3ad-
compliant device. The other ports remain in standby mode.
Aggregator
Description Aggregator
Ports Aggregate
Trunk Ports
Aggregator 1 1-3, 12-14 1-3
12-14