Cisco Catalyst 2950 Command Reference Manual page 34

channel-group
You do not have to create a port-channel interface before assigning a physical interface to a channel
group. A port-channel interface is created automatically when the channel group gets its first physical
interface.
You do not have to disable the IP address that is assigned to a physical interface that is part of a channel
group, but we highly recommend that you do so.
You can create port channels by entering the interface port-channel global configuration command or
when the channel group gets its first physical interface assignment. The port channels are not created at
runtime or dynamically.
Any configuration or attribute changes you make to the port-channel interface are propagated to all
interfaces within the same channel group as the port channel (for example, configuration changes are
also propagated to the physical interfaces that are not part of the port channel, but are part of the channel
group).
With the on mode, a usable EtherChannel exists only when a port group in on mode is connected to
another port group in on mode.
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, transmits
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 interface to a channel group, and to use the interface
for transmission. Both ends of the link cannot be set to silent.
You should exercise care when setting the mode to on (manual configuration). All ports configured in
Caution
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 Protocol (STP) loops might occur.
Examples
This example shows how to add an interface to the EtherChannel group specified as channel group 1:
Switch(config)# interface gigabitethernet0/1
Switch(config-if)# channel-group 1 mode on
You can verify your settings by entering the show etherchannel or show running-config privileged
EXEC command.
Related Commands Command
interface port-channel
port-channel
load-balance
show etherchannel
show running-config
Catalyst 2950 Desktop Switch Command Reference
2-10
Description
Accesses or creates the port channel.
Sets the load distribution method among the ports in the EtherChannel.
Displays EtherChannel information for a channel.
Displays the configuration information running on the switch. For syntax
information, select Cisco IOS Configuration Fundamentals Command
Reference for Release 12.1 > Cisco IOS File Management Commands >
Configuration File Commands.
Chapter 2 Cisco IOS Commands
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