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6-6 C
HAPTER
6: S
TATUS
M
ONITORING
AND
S
TATISTICS
Port Error Analysis
With the Port Statistics screen displayed, select the
ERROR ANALYSIS button. The Port Error Analysis
screen is displayed, as shown in Figure 6-4
.
The Port Error Analysis screen shows the following:
Port ID
The ID of the port you are currently manag-
ing.
CRC Align Errors
This counter is incremented by
one for each frame with a CRC (Cyclic Redundancy
Check) error or an alignment error. A CRC error
occurs if a frame of valid length has an invalid CRC
but does not have a framing error. It is likely that a
bit has been corrupted in transmission. An align-
ment error occurs if a frame has a CRC error and
the frame does not have an integral number of
octets. Alignment errors may be caused by a fault at
the transmitting device.
Check cables and connections for damage. If this
does not solve the problem, try changing the trans-
ceiver or adapter card of the device connected to
the port at the source of the problem.
Short Events
This counter is incremented by one
for each carrier event whose duration is less than
the short event maximum time. Short events are
error frames smaller than the minimum size defined
for Ethernet frames. They may indicate externally
generated noise causing problems on the network.
Check the cabling routing and re-route any cabling
which may be affected by external noise sources.
Figure 6-4
Port Error Analysis screen
Late Events
This counter is incremented by one
each time a collision occurs after the valid packet
minimum time. A late event is an out-of-window
collision that may occur if your Ethernet LAN
exceeds the maximum size as defined in the IEEE
standard. A late event is also counted as a collision.
Long Frames
This counter is incremented by one
each time a frame is received whose octet count is
greater than the maximum frame size but less than
Jabber frame size. Long Frames are frames that
exceed the maximum size defined for Ethernet
frames (1518 octets). If you see a high number of
long frames on your network, you should isolate the
source of these frames and examine the transceiver
or adapter card at the device. Some protocols may
generate these frames.