Cisco Catalyst 3550

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Catalyst 3550 Multilayer Switch Command Reference
OL-8566-02
Chapter 2 Catalyst 3550 Switch Cisco IOS Commands
channel-group
Defaults No channel groups are assigned.
No mode is configured.
Command Modes Interface configuration
Command History
Usage Guidelines 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, if it is not already created.
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.
For Layer 2 EtherChannels, you must configure the channel-group interface configuration command,
which automatically creates the port-channel logical interface. You cannot put Layer 2 interfaces into a
manually created port-channel interface.
You create Layer 3 port channels by using the interface port-channel command. You must manually
configure the port-channel logical interface before putting the interface into the channel group.
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).
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 interface to a channel group, and to use the interface
for transmission. Both ends of the link cannot be set to silent.
on Enable on mode.
In on mode, a usable EtherChannel exists only when both connected
port groups are in the on mode.
passive Enable LACP only if a LACP device is detected.
Passive mode places an interface into a negotiating state in which the
interface responds to LACP packets it receives but does not initiate
LACP packet negotiation. A channel is formed only with another port
group in active mode.
Release Modification
12.1(4)EA1 This command was introduced.
12.1(12c)EA1 The active and passive keywords were added.