AL2100-DS01-405-R datasheet(14/52 Pages) BOARDCOM

14 / 52 page

AL2100

Preliminary Data Sheet

11/11/02

Broa d c om Co rp o r a ti o n

Page 6

Fault Propagation

Document

AL2100-DS01-405-R

FAULT PROPAGATION

Three types of fault propagation are provided using the following logic:

TP_RCVR_ACTIVE = Wait_For_Link || TP_Link_Up;

TP_OUTPUT_EN = (FX_LINK_UP || FX2TP_DIS) && DATA_ENABLE;

FX_OUTPUT_EN = TP_RCVR_ACTIVE || TP2FX_DIS;

FIBER-TO-FIBER

This is the same as the remote fault function. When remote fault is disabled, the AL2100 disables the FX transmission if the

received SD fails.

FIBER-TO-TWISTED PAIR

This operation can be controlled via the FX2TP_DIS signal. This signal is only defined in AL2100 normal operation mode,

not in RMII testing mode. This is a reset read signal.

When this type of fault propagation is enabled, the failure of the FX link shuts down the twisted pair output.

TWISTED PAIR-TO-FIBER

This operation is controlled via the TP2FX_DIS signal. This signal is only defined in AL2100 normal operation mode. This is

a reset read signal. When this type of fault propagation is enabled, the absence of receiving energy shuts down the fiber

transmission to inform the fiber link partner about the link failure.

The AL2100 propagates idle signals from media-to-media. After reception of the idle signal (all ones), the device transmits

an idle signal to the opposite ports, i.e. TP-to-fiber or fiber-to-TP. There are two types of link failure—receive or remote

fault— also known as far-end fault.

TP Receive Link Failure

In the event of a TP-receive-link failure, the AL2100 ceases to transmit an idle signal to the fiber-optic driver. A valid TP link

signal can be either a 10BASE-T link pulse or a 100BASE-TX idle signal.

Fiber Receive Link Failure

In the event of a fiber-receive-link failure, the AL2100 ceases to transmit an idle signal to the TP driver, and puts the driver

into high-impedance mode. The device also sends a remote fault signal to the fiber-optic driver in addition to de-asserting

the DATA_OFF signal.

TP Transmit Link Failure

In the event of a TP transmit link failure, the TP far-end transceiver ceases to transmit an idle signal, and starts transmitting

FLP to the AL2100. Because the AL2100 does not understand FLP, it continues to transmit an idle signal to the fiber-optic

driver.

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