Users Guide

Layer 2 Switching Commands 679
Default Configuration
The default port priority value is 1.
Command Mode
Interface Configuration (Ethernet) mode
Interface Range mode
User Guidelines
Per IEEE 802.1AX-2008 Section 5.6, ports are selected for aggregation by each
switch based upon the port priority assigned by the switch with the higher
system priority, starting with the highest priority port of the switch with the
higher switch priority, and working downward through the ordered list of port
priority values for the ports.
The port priority of each port is a four octet binary number, formed by using
the configured port priority as the two most significant octets and the port
number as the two least significant octets. For any given set of ports, the port
with the numerically lower value of port priority has the higher priority.
The selection algorithm is reapplied upon changes in the membership of the
port channel (for example, if a link fails, or if a new link joins the group) and
any subsequent changes to the set of active links are made according to the
above algorithm.
Example
The following example configures the priority value for port 1/0/8 to 247.
console(config)#interface gigabitethernet 1/0/8
console(config-if-Gi1/0/8)#lacp port-priority 247
lacp system-priority
Use the lacp system-priority command in Global Configuration mode to
configure the Link Aggregation system priority. To reset to default, use the no
form of this command.
Syntax
lacp system-priority value