Cisco Catalyst 3750 Command Reference Manual page 64

channel-group
Command History Release
12.1(11)AX
12.1(14)EA1
12.2(25)SE
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.
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. The on keyword is the only setting that is supported when the
EtherChannel members are from different switches in the switch stack (cross-stack EtherChannel).
Caution You should exercise care when setting the mode to on (manual configuration). All ports configured in
the on mode are bundled in the same group and are forced to have similar characteristics. If the group is
misconfigured, packet loss or spanning-tree loops might occur.
A cross-stack EtherChannel supports up to two 10-Gigabit Ethernet interfaces.
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.
Do not configure a port that is an active or a not-yet-active member of an EtherChannel as an 802.1x
port. If you try to enable 802.1x on an EtherChannel port, an error message appears, and 802.1x is not
enabled.
Catalyst 3750 Switch Command Reference
2-36
Modification
This command was introduced.
The active and passive keywords were added.
The channel-group-number range was changed from 1 to 12 to 1 to 48.
Chapter 2 Catalyst 3750 Switch Cisco IOS Commands
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