D-Link DFE-680TXD manual

best baud rate, compression method, and error correction method. When the two modems have tested the phone-line 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-680TXD and the switch or hub through which it is connected into the LAN. (Switches ordinarily provide for autonegotiation; traditional hubs do not.) The parameters to be negotiated between the DFE-680TXD and its supporting switch or hub include speed (100Mbps = Fast Ethernet, or 10Mbps = traditional Ethernet) and duplex mode (half-duplex or full- duplex).

Startup communication between the two devices occurs when both devices are operating, the cable connection between them is good, and the connected notebook PC's network software is loaded. As soon as those conditions are satisfied, the preparatory process of auto-negotiation between the DFE-680TXD and its supporting device begins and proceeds automatically.

If the supporting switch or hub has autonegotiation functionality, then it and the DFE- 680TXD exchange a series of messages in which each device signals its capabilities and listens for corresponding information about the other. The auto- negotiation process requires only a few milliseconds, and the two devices select the best communication parameters supported by both devices.

If the supporting device does not have autonegotiation functionality, then its monotone (single capability) message will be recognized by the DFE-680TXD’s autonegotiation facility, and the DFE-680TXD will simply switch to the one of its own capabilities which matches that of the supporting device.

Once the auto- negotiation is completed, then the line is ready, and it will provide an optimal data channel between the DFE-680TXD and the supporting device. The line will remain ready without further auto-negotiation action until the linkage is broken. Auto- negotiation then reoccurs at any time that the linkage is restored, again making the line ready for optimal data communications.

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