Software Features Explained 23Flow Control All the ports on your Switch support flow control, which is a congestioncontrol mechanism. Congestion is caused by one or more devices sendingtraffic to an already overloaded port on the Switch. Flow control preventspacket loss and inhibits the devices from generating more packets untilthe period of congestion ends.Flow control is implemented in two ways: IEEE 802.3x standard for ports operating in full duplex. Intelligent Flow Management (IFM), a 3Com proprietary method offlow control, for ports operating in half duplex. IFM should only beenabled if the port is connected to another switch, or an endstation. Ifthe port is connected to a repeated segment with local traffic, IFMshould be disabled.For information about enabling flow control on a port, see “Configuringa Port” on page 59.Traffic Prioritization Your Switch supports IEEE 802.1p traffic prioritization, which allows datathat has been assigned a high priority to be forwarded through theSwitch without being obstructed by other data. The system works byusing the multiple traffic queues that are present in the hardware of theSwitch — high priority traffic is forwarded on a different queue fromother traffic, and it is always given preference over the other traffic.Traffic prioritization can be useful for critical applications that require ahigh Class of Service (CoS) from the network. This could include: Financial applications — Accounts departments that needimmediate access to large files and spreadsheets at the end of themonth. CAD/CAM design applications — Design departments that needpriority connections to server farms and other devices for transferringlarge files. Converged network applications — Organizations with aconverged network (that is, a network that uses the sameinfrastructure for voice data and traditional data) that require highquality voice data transmission at all times.
