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Catalyst 3550 Multilayer Switch Software Configuration Guide
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Chapter 30 Configuring EtherChannels
Configuring EtherChannels
All ports default to the same port priority. You can change the port priority of LACP EtherChannel ports
to specify which hot standby links become active first by using the lacp port-priority interface
configuration command to set the port priority to a value lower than the default of 32768.
The hot standby ports that have lower port numbers become active in the channel first unless the port
priority is configured to be a lower number than the default value of 32768.
Note
If LACP is not able to aggregate all the ports that are compatible (for example, the remote system might
have more restrictive hardware limitations), all the ports that cannot be actively included in the
EtherChannel are put in hot standby state and are used only if one of the channeled ports fails.
Configuring the LACP System Priority
You can set the system priority for all of the EtherChannels that are configured for LACP by using the
lacp system-priority privileged EXEC command. The range is from 1 to 65535.
Note
The lacp system-priority command is global. You cannot set a system priority for each
LACP-configured channel separately.
We recommend using this command only when there are a combination of LACP-configured
EtherChannels that are in both active and standby modes.
Beginning in privileged EXEC mode, follow these steps to configure the LACP system priority:
Command
Purpose
Step 1
configure terminal
Enter global configuration mode.
Step 2
lacp system-priority priority-value
Select the LACP system priority value.
For priority-value, the range is 1 to 65535. By
default, the priority value is 32768. The lower the
range, the higher the system priority. The switch
with the lower system priority value determines
which links between LACP partner switches are
active and which are in standby for each LACP
EtherChannel.
Step 3
end
Return to privileged EXEC mode.
Step 4
show running-config
or
show lacp channel-group-number internal
Verify your entries.
Step 5
copy running-config startup-config
(Optional) Save your entries in the configuration
file.