Allied Telesis AT-S62 - Manual (Page 142)

Chapter 8: Static and LACP Port Trunks
142 Section I: Basic Operations
Adminkey Parameter
The adminkey is a hexadecimal value from 1 to FFFF that identifies an
aggregator. Each aggregator on a switch must have a unique adminkey.
The adminkey is limited to a switch. Two aggregators on different switches
can have the same adminkey without creating a conflict.
LACP Port Priority Parameter
The switch uses a port’s LACP priority to determine which ports are to be
active and which in the standby mode in situations where the number of
ports in the aggregate trunk exceeds the highest allowed number of active
ports. This parameter is a hexadecimal value in a range of 1 to FFFF,
based on the port number. For instance, the priority values for ports 2 and
11 are 0002 and 000B, respectively. The lower the number, the higher the
priority. Ports with the highest priorities are designated as the active ports
in an aggregate trunk.
For example, if both 802.3ad-compliant devices support up to eight active
ports and there are a total of ten ports in the trunk, the eight ports with the
highest priorities (lowest priority values) are designated as the active
ports, and the others are placed in standby mode. If an active link goes
down on a active port, the standby port with the next highest priority is
automatically activated to take its place.
A port’s priority value is not adjustable.
The selection of the active links in an aggregate trunk is dynamic. It
changes as links are added, removed, lost or reestablished. For example,
if an active port loses its link and is replaced by another port in the standby
mode, the reestablishment of the link on the originally active port causes it
to return to the active state by virtue of its having a higher priority, while
the port that replaced it is returned to the standby mode.
Two conditions must be met in order for a port of an aggregate trunk to
function in the standby mode. Firstly, the number of ports in the trunk must
exceed the highest allowed number of active ports and, secondly, the port
must be receiving LACPDU packets from the other device. A port
functioning in the standby mode does not forward network traffic, but it
does continue to send LACPDU packets. If a port in an aggregator does
not receive LACPDU packets, it functions as a normal Ethernet port and
forwards network packets along with LACPDU packets.
Load Distribution Methods
The load distribution method determines the manner in which the switch
distributes the traffic across the active ports of an aggregate trunk. The
method is assigned to an aggregator and applies to all aggregate trunks
within it. If you want to assign different load distribution methods to
different aggregate trunks, you must create a separate aggregator for