Auto-negotiation is a mechanism that takes control of the

cable when a connection is established to a network device.

Auto-negotiation detects the various modes that exist in

the device on the other end of the wire, and advertises it

own abilities to automatically configure the highest

performance mode of interoperation.

Auto-negotiation automatically switches to the correct

technology, such as 10BASE-T, 100BASE-TX, or a

corresponding Full Duplex mode. Once the highest

performance common mode is determined, Auto-negotiation

passes control of the cable to the appropriate technology

and becomes transparent until the connection is broken.