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BusWorks
®
900EN-S005 Ethernet Switch User’s Manual Ethernet I/O
__________________________________________________________________
_______________________________________________________________________________________
Acromag, Inc. Tel:248-624-1541 Fax:248-624-9234 Email:
sales@acromag.com
http://www.acromag.com
12
STATISTIC
INTERPRETATION/ACTION
RxUndersizePkt
This counts packets that are less than the requisite
64 octets (including FCS octets), but are otherwise
well formed (good Frame Check Sequence).
This is usually the result of software errors.
Note that undersized and fragmented packets are
also referred to as “runts”.
RxOversize
This counts packets that are longer than 1522
bytes including the FCS octets (or 1536 depending
on Max Packet Size set), but are otherwise well
formed (valid CRC/FCS).
Oversized or “too long” packets are often caused
by a bad transceiver, a malfunction of the jabber
protection mechanism of the transceiver, or
excessive noise on the cable.
A transceiver on the network may be adding bits to
the packets transmitted. You can use a network
analyzer to identify the rogue transceiver and
replace it, the adapter, or the station.
A high number of these errors may also be
indicative of a speed mismatch between the switch
port and devices on this segment.
RxJabbers
Stop that incessant
jabbering, shut up
and listen!
This counts the number of frames larger than the
maximum packet size of 1522 bytes (or 1536 bytes,
depending on the maximum packet size), and that
include CRC, alignment, or symbol errors
.
Recall that Ethernet devices use electrical signaling
to determine whether or not they can transmit.
Jabbers indicate that one or more devices on the
network are sending improper electrical signals.
This is a critical failure because a jabber condition
can effectively halt all traffic on a segment, as all
other devices think the network is busy. Jabbering
is usually caused by a bad network adapter or NIC
card, and in rare cases, outside interference.
RxSymbolError
This tracks packets received with an invalid data
symbol but of legal packet size.
RxCRCerror
The CRC is a four byte value appended to a
packet. The criterion for CRC error rate is 1 CRC
error per 10^8 frames for 100base-T.
A high number of CRC errors may indicate poor
cable quality or operation in a noisy environment.
Use a cable tester, try a different cable, or try using
shielded cable.
RxAlignmentError
This is a count of the number of frames received
between 64 and 1522/1536 bytes long that do not
have an integral number of octets and include a
bad CRC (checksum).
Usually a product of collisions, duplex mismatch,
speed mismatch, or bad hardware (NIC, cable, or
switch port).
TROUBLE
-
SHOOTING
Useful Statistics