Ethernet Troubleshooting Guide - Siemens Advance Network Gateway User Manual

Ethernet Troubleshooting Guide

Description
52 Troubleshooting
The most common problems associated with the Ethernet and how to
correct them are given in the table below.
Fault
Collisions
Late Collisions
FCS Error
Probable Cause
Excessive collisions are most often caused by a
physical media problem such as:
1. missing or incorrect terminators (10Base2)
2. impedance discontinuities (such as defec-
tive connectors, cable stubs, crushed ca-
bles, incorrect cable types)
3. defective network interface cards (NIC)
4. too many network devices on a single colli-
sion domain
Causes of Late Collisions are faulty NIC card or
a network that is physically too long. A network
is physically too long, if the end-to-end signal
propagation time is greater than the minimum
legal sized frame (about 57.6 microseconds or
~58 bit times)
1. cable lengths in excess of the maximum
permitted for the cable type
2. faulty connectors or improper cabling
3. excessive numbers of repeaters between
network devices
4. defective Ethernet transceivers or defective
network interface cards (NIC)
A FCS error can be caused by a faulty NIC or
driver, cabling, hub or induced noise. A Late
Collision can result in a FCS error. Possible
causes (listed by highest probability):
1. Late Collision
2. Faulty Cable/Connectors
3. Induced noise
4. Faulty NIC or HUB
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