AM79C987 AMD [Advanced Micro Devices], AM79C987 Datasheet - Page 18

• Manufacturer Part Number: AM79C987
• Description: Hardware Implemented Management Information Base (HIMIB) Device
• Manufacturer: AMD [Advanced Micro Devices]

Frames Too Long
P[4:0] = 16–23, 31, R[4:0] = 4
Byte 0
Byte 1
Byte 2
Byte 3
“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.
Short Events
P[4:0] = 16–23, 31, R[4:0] = 5
Byte 0
Byte 1
Byte 2
Byte 3
“Short Events” is a read-only attribute that counts the
number of instances where activity is detected with a du-
ration less than the “ShortEventMaxTime” (74–82-bit
times). This attribute is a 32-bit counter with a minimum
rollover time of 16 hours.
Runts
P[4:0] = 16–23, 31, R[4:0] = 6
Byte 0
Byte 1
Byte 2
Byte 3
“Runts” is a read-only attribute that counts the number of
instances where activity is detected with a duration
greater than the “ShortEventMaxTime” (74–82-bit
times), but less than the minimum valid frame time
(512-bit times, or 64 bytes). This attribute is a 32-bit
counter with a minimum rollover time of 16 hours.
Note: Runts usually indicate collision fragments, a nor-
mal network event. In certain situation associated with
large diameter networks a percentage of runts may ex-
ceed ValidPacketMinTime.
18
D Port Read
D Port Read
D Port Read
bit 31
bit 31
bit 31
MSB
MSB
MSB
bit 7
bit 7
bit 7
P R E L I M I N A R Y
bit 24
bit 24
bit 24
bit 0
bit 0
LSB
bit 0
LSB
LSB
Am79C987
Collisions
P[4:0] = 16–23, 31, R[4:0] = 7
Byte 0
Byte 1
Byte 2
Byte 3
“Collisions” is a read-only attribute that counts the num-
ber of instances where a carrier is detected on the port,
and a collision is detected. This attribute is a 32-bit
counter with a minimum rollover time of 16 hours.
Late Events
P[4:0] = 16–23, 31, R[4:0] = 8
Byte 0
Byte 1
Byte 2
Byte 3
“Late Events” is a read-only attribute that counts the
number of instances where a collision is detected after
the LateEventThreshold (480–565-bit times) in the
frame. This event will be counted both by the “Late
Events” attribute, as well as the “Collisions” attribute.
This attribute is a 32-bit counter with a minimum rollover
time of 81 hours.
Very Long Events
P[4:0] = 16–23, 31, R[4:0] = 9
Byte 0
Byte 1
Byte 2
Byte 3
“Very Long Events” is a read-only attribute that counts
the number of times the transmitter is active in excess of
the MAU Jabber Lockup Protection (MJLP) Timer (4 ms
– 7.5 ms). This attribute is a 32-bit counter with a mini-
mum rollover time of 198 days.
D Port Read
D Port Read
D Port Read
bit 31
bit 31
bit 31
MSB
MSB
MSB
bit 7
bit 7
bit 7
AMD
bit 24
bit 24
bit 24
bit 0
bit 0
LSB
LSB
bit 0
LSB