Troubleshooting guide

Troubleshooting Guide
178
RX Source Address Changes
This count indicates the number
of times that the source address
(SA) has changed on packets
received on this port.
A count greater than one
generally indicates that this port
is connected to an ethernet
repeater or hub.
This is normal behavior. Note that the
use of repeaters/hubs is not
recommended.
RX Oversize Frames
Oversize frames are packets with
lengths of more than 1518 bytes
that have good FCS
values
Oversized frames are usually
due to software bugs in
applications running on network
devices.
No action.
RX Undersize Frames (Runts)
Undersize frames are packets
with a length of less than 64 bytes
that have good FCS
values.
Collisions No action required. Runts are normal
when collisions occur.
Excessive noise on the LAN 1. Check for improper cabling— e.g.,
ethernet cables routed too close to
power lines or equipment.
2. Check cable terminations for faults.
3. Locate and replace defective network
device.
TX Collisions
This counter indicates the
number of transmit collisions.
Half Duplex Operation:
In a half-duplex environment
collisions are normal and the
rate of collisions will increase as
the network traffic increases.
There might be a problem in the
network if the rate of collisions
increases without a
corresponding increase in
network traffic.
Practical network bandwidth
utilization is about 70%. If the
network is experiencing
an excessive number of
collisions, it could be an
indication that the network is
becoming congested.
Full Duplex Operation:
Collisions should be minimal in a
full duplex network.
Collisions in half-duplex networks are
normal.
Collisions in full-duplex networks should
be minimal.
Multiple Collisions
This counter indicates the
number of times that a
transmitted packet encountered
more than one collision but fewer
than 16. This counter increments
only if the device is in half-duplex
mode.
See Excessive Collisions. See Excessive Collisions.
Table 60: Frame Length Errors
Counter Cause Corrective Action
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