38-16
Cisco IE 3000 Switch Software Configuration Guide
OL-13018-03
Chapter 38 Configuring EtherChannels and Link-State Tracking
Configuring EtherChannels
In priority comparisons, numerically lower values have higher priority. The priority decides which ports
should be put in standby mode when there is a hardware limitation that prevents all compatible ports
from aggregating.
Determining which ports are active and which are hot standby is a two-step procedure. First the system
with a numerically lower system priority and system-id is placed in charge of the decision. Next, that
system decides which ports are active and which are hot standby, based on its values for port priority
and port number. The port-priority and port-number values for the other system are not used.
You can change the default values of the LACP system priority and the LACP port priority to affect how
the software selects active and standby links. For more information, see the
“Configuring the LACP
System Priority” section on page 38-16
and the
“Configuring the LACP Port Priority” section on
page 38-16
.
Configuring the LACP System Priority
You can configure the system priority for all the EtherChannels that are enabled for LACP by using the
lacp system-priority
global configuration command. You cannot configure a system priority for each
LACP-configured channel. By changing this value from the default, you can affect how the software
selects active and standby links.
You can use the
show etherchannel summary
privileged EXEC command to see which ports are in the
hot-standby mode (denoted with an H port-state flag).
Beginning in privileged EXEC mode, follow these steps to configure the LACP system priority. This
procedure is optional.
To return the LACP system priority to the default value, use the
no lacp system-priority
global
configuration command.
Configuring the LACP Port Priority
By default, all ports use the same port priority. If the local system has a lower value for the system
priority and the system ID than the remote system, you can
affect which of the hot-standby links become
active first by changing the port priority of LACP EtherChannel ports to a lower value than the default
.
The hot-standby ports that have lower port numbers become active in the channel first. You can use the
show etherchannel summary
privileged EXEC command to see which ports are in the hot-standby
mode (denoted with an
H
port-state flag).
Command
Purpose
Step 1
configure terminal
Enter global configuration mode.
Step 2
lacp system-priority
priority
Configure the LACP system priority.
For
priority
, the range is 1 to 65535. The default is 32768.
The lower the value, the higher the system priority.
Step 3
end
Return to privileged EXEC mode.
Step 4
show running-config
or
show lacp sys-id
Verify your entries.
Step 5
copy running-config startup-config
(Optional) Save your entries in the configuration file.
