About 802.3u Fast Ethernet specification (fast link pulse)

Fast Link pulse

Auto-negotiation takes place using fast
Link pulse (random) signals. these signals are a modified version of the normal link pulse (NLP) signals used for verifying link integrity, as defined in the original 10base-t specifications. the specified signals are generated automatically at power-up, or may be
Selected manually through the management interface to an auto-negotiation device.

The Fast Link pulse signals are designed to coexist with NLP signals, so that a 10base-t device that uses NLP signals will continue to detect the proper link integrity even when attached to an auto-negotiation hub that sends has signals. like the original 10base-t
Link pulse, the specified signals take place during idle times on the network link and do not interfere with normal traffic. note that both normal link pulses and fast link pulses are specified only for twisted-pair media using eight-pin connectors, such as 100base-tx
Over unshielded twisted-pair. This means that network devices and repeater ports linked over fiber optic segments cannot participant in auto-negotiation.

The specified signals are used to send information about device capabilities. the auto-Negotiation Protocol contains rules for device configuration based on this information. this is how a hub and the device attached to that hub can be automatically negotiate and configure
Themselves to use the highest performance mode of operation.

The auto-negotiation feature is optional, and therefore the auto-negotiation protocol is designed to work with 100base-t interfaces that do not support fast link pulses and auto-negotiation as well as older 10base-t interfaces that were built before auto-Negotiation
Existed. the auto-negotiation system has des an optional management interface that allows you to disable auto-negotiation, or to manually force the negotiation process to take place. the management interface allows you to manually select a specific operational
Mode for a given hub port.

    The above is an English document I have found:   (Fast Ethernet) Automatic negotiation using the fast link pulse signal is a variant of the general link pulse signal (NLP. NLP is used for integrity of the verification link and is first defined in the 10base-t specification manual. generally, the butler signal is automatically negotiated when the power supply starts. You can also manually configure the management interface of the automatic negotiation device.  Attention is designed to coexist with NLP signals. Therefore, when a 10base-t device is connected to a hub that sends the attention signal for automatic negotiation, it will continue to send NLP to check the integrity of the link. like 10 BASE-T negotiation, the RST negotiation signal occurs in the idle time of the link and does not interfere with normal traffic communication. we noticed that both NLP and Asn are dedicated to the twisted pair media of the 8-wire connector, such as the UTP of 100base-tx. this means that the network devices connected to the optical fiber segment and the forwarding port cannot be automatically negotiated.  The RST signal is used to send device capacity information. the rules contained in Automatic negotiation are to use the information to configure the device. this is why when a device is connected to the hub, the hub can automatically negotiate and configure the maximum rate of execution mode between them.  The automatic negotiation function is optional. Therefore, the automatic negotiation protocol is designed for the 100base-t interface, and does not provide the callback and automatic negotiation for the 10base-t interface before the automatic negotiation protocol is generated. the automatic negotiation system includes an optional management interface that allows you to disable automatic negotiation or manually force negotiation. the management interface allows you to manually select a clear operation mode to act on a hub port.                                                                                                                                                                                      By: Troy 

From: http://www.ethermanage.com/ethernet/100quickref/ch13qr_3.html#HEADING2