Cisco Catalyst 3560X-24P Command Reference Manual page 114

channel-group
Defaults No channel groups are assigned.
No mode is configured.
Command Modes
Interface configuration
Command History Release
12.2(53)SE2
Usage Guidelines For Layer 2 EtherChannels, you do not have to create a port-channel interface first by using the interface
port-channel global configuration command before assigning a physical port to a channel group.
Instead, you can use the channel-group interface configuration command. It automatically creates the
port-channel interface when the channel group gets its first physical port if the logical interface is not
already created. If you create the port-channel interface first, the channel-group-number can be the same
as the port-channel-number, or you can use a new number. If you use a new number, the channel-group
command dynamically creates a new port channel.
You do not have to disable the IP address that is assigned to a physical port that is part of a channel group,
but we strongly recommend that you do so.
You create Layer 3 port channels by using the interface port-channel command followed by the no
switchport interface configuration command. You should manually configure the port-channel logical
interface before putting the interface into the channel group.
After you configure an EtherChannel, configuration changes that you make on the port-channel interface
apply to all the physical ports assigned to the port-channel interface. Configuration changes applied to
the physical port affect only the port where you apply the configuration. To change the parameters of all
ports in an EtherChannel, apply configuration commands to the port-channel interface, for example,
spanning-tree commands or commands to configure a Layer 2 EtherChannel as a trunk.
If you do not specify non-silent with the auto or desirable mode, silent is assumed. The silent mode is
used when the switch is connected to a device that is not PAgP-capable and seldom, if ever, sends
packets. A example of a silent partner is a file server or a packet analyzer that is not generating traffic.
In this case, running PAgP on a physical port prevents that port from ever becoming operational.
However, it allows PAgP to operate, to attach the port to a channel group, and to use the port for
transmission. Both ends of the link cannot be set to silent.
In the on mode, an EtherChannel exists only when a port group in the on mode is connected to another
port group in the on mode.
You should use care when using the on mode. This is a manual configuration, and ports on both ends of
Caution
the EtherChannel must have the same configuration. If the group is misconfigured, packet loss or
spanning-tree loops can occur.
Do not configure an EtherChannel in both the PAgP and LACP modes. EtherChannel groups running
PAgP and LACP can coexist on the same switch or on different switches in the stack (but not in a
cross-stack configuration). Individual EtherChannel groups can run either PAgP or LACP, but they
cannot interoperate.
If you set the protocol by using the channel-protocol interface configuration command, the setting is
not overridden by the channel-group interface configuration command.
Catalyst 3750-X and 3560-X Switch Command Reference
2-82
Chapter 2
Modification
This command was introduced.
Catalyst 3750-X and 3560-X Switch Cisco IOS Commands
OL-21522-02