Allied Telesis AT-S63 - Manual (Page 154)

Chapter 8: Static and LACP Port Trunks
154 Section I: Basic Features
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 restricted to a switch. Two aggregators on different
switches can have the same adminkey without generating a conflict.
LACP Port Priority Value
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.
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.
A port’s priority value is not adjustable.
Two conditions must be met in order for a port that is a member of an
aggregate trunk to function in the standby mode. First, the number of ports
in the trunk must exceed the highest allowed number of active ports and,
second, the port must be receiving LACPDU packets from the other
device. A port functioning in the standby mode does not forward network
traffic, but does continue to send LACPDU packets. If a port that is part of
an aggregator does not receive LACPDU packets, it functions as a normal
Ethernet port and forwards network packets along with LACPDU packets.