Cisco Systems 3750E Configuring Ieee 802.3x Flow Control, Flowcontrol receive on off desired

Chapter 11 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-idinterface 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 cannot 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 operate in either direction. In case of congestion, no indication 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 privileged EXEC mode, follow these steps to configure flow control on an interface:

	Command		Purpose
Step 1	configure terminal		Enter global configuration mode
Step 2	interface interface-id		Specify the physical interface to be configured, and enter
			interface configuration mode.
Step 3	flowcontrol {receive} {on off desired}		Configure the flow control mode for the port.
Step 4	end		Return to privileged EXEC mode.
		Catalyst 3750-E and 3560-E Switch Software Configuration Guide
11-24			OL-9775-02