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Catalyst 3750-E and 3560-E Switch Software Configuration Guide
OL-9775-02
Chapter11 Configuring Interface Characteristics
Configuring Ethernet Interfaces
Use the no speed and no duplex interface configuration commands to return the interface to the default
speed and duplex settings (autonegotiate). To return all interface settings to the defaults, use the default
interface interface-id interface configuration command.
This example shows how to set the interface speed to 100 Mb/s and the duplex mode to half on a
10/100/1000 Mb/s port:
Switch# configure terminal
Switch(config)# interface gigabitethernet1/0/3
Switch(config-if)# speed 10
Switch(config-if)# duplex half
This example shows how to set the interface speed to 100 Mb/s on a 10/100/1000 Mb/s port:
Switch# configure terminal
Switch(config)# interface gigabitethernet1/0/2
Switch(config-if)# speed 100
Configuring IEEE 802.3x Flow Control
Flow control enables connected Ethernet ports to control traffic rates during congestion by allowing
congested nodes to pause link operation at the other end. If one port experiences congestion and ca nnot
receive any more traffic, it notifies the other port by sending a pause frame to stop sending until the
condition clears. Upon receipt of a pause frame, the sending device stops sending any data packets,
which prevents any loss of data packets during the congestion period.
Note Catalyst 3750-E or 3560-E ports can receive, but not send, pause frames.
You use the flowcontrol interface configuration command to set the interface’s ability to receive pause
frames to on, off, or desired. The default state is off.
When set to desired, an interface can operate with an attached device that is required to send
flow-control packets or with an attached device that is not required to but can send flow-control packets.
These rules apply to flow control settings on the device:
•receive on (or desired): The port cannot send pause frames but can operate with an attached device
that is required to or can send pause frames; the port can receive pause frames.
•receive off: Flow control does not op erate in either direction. In case of congestion, no i ndication
is given to the link partner, and no pause frames are sent or received by either device.
Note For details on the command settings and the resulting flow control resolution on local and remote ports,
see the flowcontrol interface configuration command in the command reference for this release.
Beginning in privi leged EXEC mode , follow these ste ps to configure flow control on an interface:
Command Purpose
Step1 configure terminal Enter global configuration mode
Step2 interface interface-id Specify the physical interface to be configured, and enter
interface configuration mode.
Step3 flowcontrol {receive} {on | off | desired} Configure the flow control mode for the port.
Step4 end Return to privileged EXEC mode.