AM79C987JC datasheet(17/30 Pages) AMD

17 / 30 page

AMD

P R E L I M I N A R Y

Am79C987

Note that the contents of all attribute registers are main-

tained during an external reset.

These attributes and their definitions comply with the

IEEE 802.3k Layer Management for 10 Mbyte/s

Baseband Repeaters Repeater Management Standard.

A brief summary of attribute description is included here

for reference only. For detailed description, refer to the

IEEE 802.3k document.

Readable Frames

P[4:0] = 16–23, 31 , R[4:0] = 0

Byte 0

Byte 1

Byte 2

Byte 3

bit 7

bit 31

bit 0

bit 24

MSB

LSB

D Port Read

“Readable Frames” is a read-only attribute that counts

the number of valid frames detected by the port. Valid

frames are from 64 bytes to 1518 bytes in length, have a

valid frame CRC and are received without a collision.

This attribute is a 32-bit counter with a minimum rollover

time of 80 hours.

Readable Octets

P[4:0] = 16–23, 31, R[4:0] = 1

Byte 0

Byte 1

Byte 2

Byte 3

bit 7

bit 31

bit 0

bit 24

MSB

LSB

D Port Read

“Readable Octets” is a read-only attribute that counts

the number of octets received on each port. This num-

ber is determined by adding the frame length to this reg-

ister at the completion of every valid frame. This

attribute is a 32-bit counter with a minimum rollover time

of 58 minutes.

Frame Check Sequence (FCS) Errors

P[4:0] = 16–23, 31 , R[4:0] = 2

Byte 0

Byte 1

Byte 2

Byte 3

bit 7

bit 31

bit 0

bit 24

MSB

LSB

D Port Read

“Frame Check Sequence Errors” is a read-only attribute

that counts the number of frames detected on each port

with an invalid frame check sequence. This counter is in-

cremented on each frame of valid length (64 bytes to

1518 bytes) that does not suffer a collision during the

frame. This counter is incremented on each invalid

frame, however it is not incremented for frames with

both framing errors and frame check sequence errors.

This attribute is a 32-bit counter with a minimum rollover

time of 80 hours.

Alignment Errors

P[4:0] = 16–23, 31, R[4:0] = 3

Byte 0

Byte 1

Byte 2

Byte 3

bit 7

bit 31

bit 0

bit 24

MSB

LSB

D Port Read

“Alignment Errors” is a read-only attribute that counts

the number of frames detected on each port with an FCS

error and a framing error. This counter is incremented

on each frame of valid length (64 bytes to 1518 bytes)

that does not suffer a collision during the frame. Frames

that have both framing errors and FCS errors are

counted by this attribute, but not by the “Frame Check

Sequence Errors” attribute. This attribute is a 32-bit

counter with a minimum rollover time of 80 hours.

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