fast link pulse (Ethernet) (FLP)

The autonegotiation procedure is used to detect the individual stations with regard to the Ethernet variant used and its speed. Before autonegotiation is applied, each 100Base-T station first sends the Fast Link Pulse (FLP). If a 10Base-T station receives such an FLP pulse, it interprets the bursty pulse as an ordinary link test and responds with Normal Link Pulses( NLP). If a 100Base-T station receives an NLP pulse, it automatically switches to the lower 10Base-T data rate.

The Fast Link Pulse is sent at a time interval of 16.8ms +/-8ms. It is a burst consisting of 17 clock pulses and 16 data pulses and has a total duration of 2 ms. The 17 clock pulses contain the link pulse and clock information. The 16 data pulses represent the link code word (LCW) and define the data information of the FLP pulse.