D-Link DFE-650TX Product Manual - Page 5

DFE-650 Series Fast Ethernet PC Card User's Guide also offers 10Mbps Ethernet operation, in full-duplex and halfduplex modes. Selection of the best operation mode in any given installation is automatically governed by autonegotiation. About Autonegotiation The basic idea of autonegotiation can be understood by reflecting for a moment on the familiar process of making a dialup connection between two modems. You have probably heard some gravelly−sounding exchanges between your local modem and a modem at the other end of a telephone line. (These exchanges are ordinarily played out through a speaker in your local modem). As irritating as those few seconds of noise may be, they do let you know that your modem and the remote modem are on the job, preparing for your intended communication with the remote computer. The preparatory work of the two modems during those few seconds before you see the " connect" message is to negotiate the best data communication scheme which is supported by both modems, and which is suitable for the quality of the telephone-line connection between them. The parameters to be settled between the two modems include best baud rate, compression method, and error correction method. When the two modems have tested the phoneline quality and have switched to the combination of parameters which will provide the best data communication, then you are given the " connect" message which signals the end of the inter-modem negotiation and the beginning of your intended communication with the remote computer. Autonegotiation between devices within an Ethernet LAN is similar in concept, but much briefer. The two devices involved in the autonegotiation will be your DFE-650 Series PC Card and the hub or switch through which it is connected into the LAN. (Switches ordinarily provide autonegotiation functionality; hubs usually do Introduction 3