Ref: 03250405
Title: Explanation of Netstatistics on IB Products
Date: 12/87

Copyright 3Com Corporation, 1991.  All rights reserved.

IECM:  LANCE Chip (AM7990 - Advanced Micro Devices)

IBCM:  Intel 82586

CRC:  Cyclic Redundancy Error - computed as the bits are sent
and is appended at the end of the out-going frame.  On reception,
the CRC computation should give a known result; other-wise an
error is indicated.

Frame:  The LANCE chip can handle up to 7 dribbling bits when a
received packet terminates.  During the reception, the CRC is
generated on every serial bit (including the dribbling bits)
coming from the cable, and it gets stored internally.  The
framing error is reported to the user as follows:  (1) If the
number of the dribbling bits are 1 to 7 bits and there is no CRC
error, then there is no framing error.  (2) If the number of the
dribbling bits are less than 8 and there is a CRC error, then
there is also a Framing error.  (3) If the number of the
dribbling bits = 0, then there is no framing error.  There may or
may not be a CRC error.  (This applies to 82586 chip also.)

Long:  Illegal length.  Packet is rejected for being over 1518
bytes.  Packets under 64 bytes are also rejected but are not
counted.

1Coll:  A collision that occurs within 6 byte times (4.8ms) will
result in the packet being rejected because of an address
mismatch.  This counts the number of frames which required one
retry.

MColl:  Multiple collision.  With a collision that occurs within
a 64 byte time (51.2ms), the controller will attempt to retrieve
it 15 more times.  This counts the number of frames which
required between two and fifteen retries.

LColl:  Late collision.  Collision that occurs after 64 byte
times resulting in a truncated packet.

EColl:  Excessive collision.  If all 16 attempts at transmission
fail, the chip gives up ownership for this packet and processes
the next packet.

NetErr:  IECM (LANCE):  Loss of carrier bit set after the packet
has been transmitted.  IBCM (82586):  Loss of CTS during packet
transmission.

Defer:  NOT AN ERROR  Deferred because of traffic on the link.

Lost:  Records the number of correct incoming frames discarded
due to lack of memory resources (buffer space or received frame
descriptors) or because the memory bus was not available in time
to transfer them.

                TRANSMIT ERRORS                 RECEIVE ERRORS
                ---------------                 --------------
                1Coll                           CRC
                MColl                           Frame
                LColl                           Long
                EColl                           Lost
                NetErr
                Defer
