Cisco WS-C6506 Software Manual page 134

Understanding How the Link Aggregation Control Protocol Works
You must assign a port priority that can be specified automatically or through the CLI (see the
"Specifying the Port Priority" section on page
used with the port number to form the port identifier. The port priority is used to decide which ports
should be put in standby mode when there is a hardware limitation that prevents all compatible ports
from aggregating.
Administrative key
•
You must assign an administrative key value that can be specified automatically or through the CLI
to each port in the switch (see the
The ability of a port to aggregate with other ports is defined with the administrative key. A port's
ability to aggregate with other ports is determined by these factors:
When enabled, LACP always tries to configure the maximum number of compatible ports in a channel,
up to the maximum that is allowed by the hardware (eight ports). If LACP is not able to aggregate all the
ports that are compatible (for example, the remote system might have more restrictive hardware
limitations), then all the ports that cannot be actively included in the channel are put in hot standby state
and are used only if one of the channeled ports fails.
You can configure different channels with ports that have been assigned the same administrative key. For
example, if eight ports are assigned the same administrative key, you may configure four ports in a
channel using LACP active mode and the remaining four ports in a manually configured channel using
the on mode. An administrative key is meaningful only in the context of the switch that allocates it; there
is no global significance to administrative key values.
Catalyst 6500 Series Switch Software Configuration Guide—Release 8.7
6-14
– Port physical characteristics, such as data rate, duplex capability, and point-to-point or shared
medium
Configuration constraints that you establish
–
6-16) to each port in the switch. The port priority is
"Specifying an Administrative Key Value" section on page
Chapter 6 Configuring EtherChannel
OL-8978-04
6-16).