Cisco Catalyst 3750 Metro - Page 59

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Catalyst 3750 Metro Switch Command Reference
OL-9645-10
Chapter 2 Catalyst 3750 Metro Switch Cisco IOS Commands
channel-group
Defaults No channel groups are assigned.
No mode is configured.
Command Modes Interface configuration
Command History
Usage Guidelines For Layer 2 EtherChannels, you do not have to create a port-channel 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 when the channel group gets its first physical port if the logical interface is not already
created. If you create the port-channel 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 apply to
all the physical ports assigned to the port-channel. 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, 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.
With the on mode, a usable EtherChannel exists only when a port group in the on mode is connected to
another port group in the on mode.
Caution You should use care when using the on mode. This is a manual configuration, and ports on both ends of
the EtherChannel must have the same configuration. If the group is misconfigured, packet loss or
spanning-tree loops can occur.
Note Enhanced-services (ES) port cannot be bundled with non ES ports.
Release Modification
12.1(14)AX This command was introduced.