D-Link DGE-560T - Gigabit PCI-Express SNMP VLAN Flow Control Network Adapter User Manual page 44

Auto-negotiation between devices within an Ethernet LAN is similar in concept, but much briefer. The two devices involved in the auto-
negotiation will be your DGE-560T and the switch or hub through which it is connected into the LAN. (Switches ordinarily provide for auto-
negotiation; traditional hubs do not.) The parameters to be negotiated between the DGE-560T and its supporting switch or hub include
speed (1000Mbps = Gigabit Ethernet, or 100Mbps = Fast 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 DGE-560T and its supporting device begins and proceeds automatically.
If the supporting switch or hub has auto-negotiation functionality, then it and the DGE-560T 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 auto-negotiation functionality, then its monotone (single capability) message will be recognized by
the DGE-560T's auto-negotiation facility, and the DGE-560T will simply switch to the one of its own capabilities that matches that of the
supporting device.
Once the auto-negotiation is completed, the line is ready, and it will provide an optimal data channel between the DGE-560T and the
supporting device. The line will remain ready without further auto-negotiation action until the link is broken. Auto-negotiation then reoccurs
at any time that the link is restored, again making the line ready for optimal data communications.
D-Link DGE-560T User Manual