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Catalyst 3550 Multilayer Switch Software Configuration Guide
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Chapter21 Configuring EtherChannel Configuring EtherChannel
Note The Catalyst 3550 supports address learning only on aggregate ports even though the physical-port
keyword is provided in the CLI. The pagp learn-method command and the pagp port-priority
command have no effect on the switch hardware, but they are required for PAgP interop erability with
devices that only support address learning by physical ports, such a s t he Cata lyst 1 900 swi tch .
When the link partner to the Catalyst 3550 switch is a physical learner, we recommend that you
configure the switch as a physical-port learner by usin g th e pagp learn-method physical-port
interface configuration command and to set the load-distribution method based on the source MAC
address by using the port-channel load-balance src-mac global configuration command. Use the
pagp learn-method command only in this situation.
Beginning in privileged EXEC mode, follow these steps to configure your switch as a PAgP
physical-port learner and to adjust the priority so that the same port in the bundle is selected for sending
packets:
To return the priority to its default setting, use the no pagp port-priority interface configuration
command. To return the learning method to its default setting, use the no pagp learn-method interface
configuration command.
Command Purpose
Step1 configure terminal Enter global configuration mode.
Step2 interface interface-id Enter interface configuration mode, and specify the interf ace for
transmission.
Step3 pagp learn-method physical-port Select the PAgP learning method.
By default, aggregation-port learning is selected, which means
the switch sends packets to the source by using any of the
interfaces in the EtherChannel. With aggregate-port learning, it
is not important on which physical port the packet arrives.
Select physical-port to connect with another switch that is a
physical learner. Make sure to configure the port-channel
load-balance global configuration command to src-mac as
described in the “Configuring EtherChannel Load Balancing”
section on page 21-13.
The learning method must be configured the same at both ends
of the link.
Step4 pagp port-priority priority Assign a priority so that the selected interface is chosen for
packet transmission.
For priority, the range is 0 to 255. The default is 128. The higher
the priority, the more likely that the interface will be used for
PAgP transmission.
Step5 end Return to privileged EXEC mode.
Step6 show running-config
or
show pagp channel-group-number internal
Verify your entries.
Step7 copy running-config startup-config (Optional) Save your entries in the configuration file.