82551IT Datasheet, PDF (63/102 Pages) Intel Corporation – Fast Ethernet PCI Controller

Networking Silicon — 82551IT
8.2
Statistical Counters
The 82551IT provides information for network management statistics by providing on-chip
statistical counters that count a variety of events associated with both transmit and receive. The
counters are updated by the 82551IT when it completes the processing of a frame (that is, when it
has completed transmitting a frame on the link or when it has completed receiving a frame). The
Statistical Counters are reported to the software on demand by issuing the Dump Statistical
Counters command or Dump and Reset Statistical Counters command in the SCB Command Unit
Command (CUC) field.
Table 23. Statistical Counters
ID
Counter
Description
0 Transmit Good Frames
This counter contains the number of frames that were
transmitted properly on the link. It is updated only after the
actual transmission on the link is completed, not when the
frame was read from memory, as is done for the Transmit
Command Block status.
4
Transmit Maximum Collisions
(MAXCOL) Errors
This counter contains the number of frames that were not
transmitted because they encountered the configured
maximum number of collisions.
8
Transmit Late Collisions
(LATECOL) Errors
This counter contains the number of frames that were not
transmitted due to an encountered collision after the
configured slot time.
12 Transmit Underrun Errors
A transmit underrun occurs because the system bus cannot
keep up with the transmission. This counter contains the
number of frames that were either not transmitted or
retransmitted due to a transmit DMA underrun. If the 82551IT
is configured to retransmit on underrun, this counter may be
updated multiple times for a single frame.
This counter contains the number of frames that were
16 Transmit Lost Carrier Sense (CRS) transmitted by the 82551IT despite the fact that it detected the
de-assertion of CRS during the transmission.
20 Transmit Deferred
This counter contains the number of frames that were
deferred before transmission due to activity on the link.
24 Transmit Single Collisions
This counter contains the number of transmitted frames that
encountered one collision.
28 Transmit Multiple Collisions
This counter contains the number of transmitted frames that
encountered more than one collision.
32 Transmit Total Collisions
This counter contains the total number of collisions that were
encountered while attempting to transmit. This count includes
late collisions and frames that encountered MAXCOL.
36 Receive Good Frames
This counter contains the number of frames that were
received properly from the link. It is updated only after the
actual reception from the link is completed and all the data
bytes are stored in memory.
40 Receive CRC Errors
This counter contains the number of aligned frames discarded
because of a CRC error. This counter is updated, if needed,
regardless of the Receive Unit state. The Receive CRC Errors
counter is mutually exclusive of the Receive Alignment Errors
and Receive Short Frame Errors counters.
Datasheet
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