AM79C983A Advanced Micro Devices, AM79C983A Datasheet - Page 42

• Manufacturer Part Number: AM79C983A
• Description: Integrated Multiport Repeater 2 (IMR2)
• Manufacturer: Advanced Micro Devices

The contents of all attribute registers are maintained
during hardware or software reset.
These attributes and their definitions comply with the
IEEE 802.3 Repeater Management standard,
Section19 ( Layer Management for 10 Mb/s Baseband
Repeaters) . A brief description of attributes is included
here for reference only. For more details refer to the
IEEE document. An IMR2-based hub can be designed
that will comply with IETF RFC 1515 and RFC 1516.
The Port Attribute Registers can be written into if one of
two conditions are met. The first is when either the M bit
or the R bit on the Device Configuration Register is set.
The second is when the corresponding port is disabled.
Readable Frames
Address:
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 roll-
over time of 80 hours.
Readable Octets
Address:
Readable Octets is a read-only attribute that counts the
number of octets received on each port. This number is
determined by adding the frame length to this register at
the completion of every valid frame. This attribute is a 32-
bit counter with a minimum rollover time of 58 minutes.
42
Byte 0
Byte 1
Byte 2
Byte 3
Byte 0
Byte 1
Byte 2
Byte 3
bit 31
bit
D Port Read
bit 7
MSB
D Port Read
bit 7
MSB
31
1110 0000
1110 0001
P R E L I M I N A R Y
bit 0
bit 24
bit 0
bit
LSB
LSB
Am79C983A
24
Frame Check Sequence (FCS) Errors
Address:
FrameCheckSequence (FCS) 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 incremented 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
Address:
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.
Frames Too Long
Address:
Frames Too Long is a read-only attribute that counts
the number of frames that exceed the maximum valid
packet length of 1518 bytes. This attribute is a 32-bit
counter with a minimum rollover time of 61 days.
Byte 0
Byte 1
Byte 2
Byte 3
Byte 0
Byte 1
Byte 2
Byte 3
Byte 0
Byte 1
Byte 2
Byte 3
MSB
MSB
D Port Read
bit 7
bit
MSB
D Port Read
bit 7
bit 31
D Port Read
bit 7
bit 31
31
1110 0010
1110 0011
1110 0100
bit 0
bit
bit 0
bit 24
bit 0
bit 24
LSB
LSB
LSB
24