BusWorks
®
900EN-S005 Ethernet Switch User’s Manual Ethernet I/O
__________________________________________________________________
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Acromag, Inc. Tel:248-624-1541 Fax:248-624-9234 Email:
http://www.acromag.com
14
STATISTIC
INTERPRETATION/ACTION
TxTotalCollision
TxExcessiveCollision
TxSingleCollision
TxMultipleCollision
These count the
number of times
packets have
collided on the
network (i.e. the
number of messages
retransmitted
because of a
collision).
Collisions are detected by the transmitting station
and indicate that two devices happened to detect
that the network is idle and tried to transmit at the
same time. Since only one device may transmit at
a time, both devices must stop sending and attempt
to retransmit. The retransmission algorithm
attempts to prevent the packets from transmitting at
the same time again, but collisions may still occur
and this process will repeat itself until the packets
finally pass onto the network, or the packets may
be discarded after 16 consecutive collisions.
Note that only transmitting hosts can be aware of
collisions and that collisions cannot occur for full-
duplex communication (one device connected to a
switch port).
Collisions also result from an over-extended LAN
where the cable is too long or where more than two
repeaters are used between stations.
A high number of collisions is also indicative of a
congested network and some nodes may need to
be relocated to another segment.
A node on the segment may also have a faulty
adapter that is not listening before broadcasting
and you may have to isolate each network adapter
to see if the problem disappears.
Guidelines for collision rates are as follows:
●
10% is a normal rate for shared segments.
●
30% is a rate where collisions begin to interfere
with performance.
●
70% is judged to be a practical limit where below
this the network is considered functional.
TROUBLE
-
SHOOTING
Useful Statistics
