Port statistics in the show statistics command (Continued)TABLE 33
Parameter Description
InDiscards The total number of packets that were received and then dropped due to a lack of
receive buffers.
OutErrors The total number of packets with internal transmit errors such as TX underruns.
CRC The total number of packets received for which all of the following is true:
• The data length is between 64 bytes and the maximum allowable frame size.
• No Collision or Late Collision is detected.
• The CRC is invalid.
Collisions The total number of packets received in which a Collision event was detected.
InErrors The total number of packets received that had Alignment errors or PHY errors.
NOTE
Excessive errors for some counters usually indicate a problem. When you operate at
a half-duplex setting, some data link errors incrementing in Frame Check Sequence
(FCS), alignment, runts, and collision counters are normal. Generally, a one percent
ratio of errors to total traffic is acceptable for half-duplex connections. If the ratio of
errors to input packets is greater than two or three percent, performance degradation
could be noticed.
In half-duplex environments, it is possible for both the switch and the connected
device to sense the wire and transmit at exactly the same time and result in a
collision. Collisions may cause runts, errors in FCS, and alignment errors due to the
frame not being completely copied to the wire, resulting in fragmented frames. When
you operate at full-duplex, errors in FCS, Cyclic Redundancy Check (CRC),
alignment, and runt counters must be minimal.
LateCollisions The total number of packets received in which a Collision event was detected, but
for which a receive error (Rx Error) event was not detected.
InGiantPkts The total number of packets for which all of the following is true:
• The data length is longer than the maximum allowable frame size.
• No Rx Error is detected.
NOTE
Packets are counted for this statistic regardless of whether the CRC is valid or
invalid.
Network Monitoring
234 FastIron Ethernet Switch Administration Guide
53-1003625-01
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