3Com 3C16630A, User Manual

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D-3
DUA1663-0BAA03
Multicast Frames This is the total number of multicast frames seen at
the repeater, hub or port. A multicast frame is one that is addressed to
a group of MAC addresses (that is, several devices) on the network. The
total number of multicast frames will normally be a small percentage of
the value seen for unicast frames.
A high level of multicast frames can adversely affect network
performance.
Runt Frames Runt frames are frames that are smaller than the
minimum frame size defined for 802.3 frames, but longer than Short
Events. Runt frames may occur as the result of collisions, and will be
propagated around the network. This is a normal part of CSMA/CD
operation and is not an error.
Short Events Short Events are smaller than runt frames and are errors.
They may indicate externally generated noise causing problems on the
network.
Check the cable routing and re-route any cabling which may be
affected by external noise sources.
Too Long Frames Too Long Frames are frames that exceed the
maximum size for 802.3 frames (1518 octets).
If you see a high number of such frames you will need to isolate the
source of these frames and examine the transceiver or adapter card at
the device. However, some network protocols cause these frames.
Total Collisions Collisions are a normal part of 802.3 operation and
occur if two devices attempt to transmit at the same time.
A sudden sustained increase in the number of collisions may indicate a
problem with a device or cabling on the network, particularly if this is
not accompanied by a general increase in traffic.
Total Errors This field should be a small proportion of the Good
Frames figure. It is the sum of the following errors seen in the unit:
FCS Errors, Alignment Errors, Short Events, Too Long Frames, Very Long
Events, Data Rate Mismatches, Late Events.
Transmit Collisions Transmit collisions are collisions that take place at
the stack, as opposed to those that take place on the network and are