Rx short errors
Function: Shows the number of frames received that were shorter than minimum collision
fragments.
Significance: Shorts can be caused by noisy connections, cable faults and faults in
network hardware. If they occur often, remedial action should be taken.
Rx CRC errors
Function: Shows the number of frames received on the port that have been corrupted during
transmission. A CRC error is registered when the 4-byte checksum is invalid, that is the
CRC information in the frame does not match the CRC computed by the receiving station.
Significance: The frame will be discarded. Re-transmission by a higher-level protocol is
required. CRC errors are usually caused by cable faults and faults in network hardware.
Rx alignment errors
Function: Shows the number of frames received that have an alignment error. Alignment
errors are frames that are longer than 64 bytes, have a bad CRC and are not an integral
number of bytes in length;-that is; the number of bits in the frame is not divisible by 8.
Significance: Frames with alignment errors are discarded. Too high a proportion of
alignment errors will severely affect performance because the dropped frames have to be
retransmitted by higher-level protocols. Alignment errors are usually caused by cable or
transceiver faults.
Rx long errors
Function: Shows the number of frames that are longer than the legal maximum length of 1518
bytes but shorter than 6000 bytes.
Significance: Longs can affect general performance and may result in users being
disconnected. The station transmitting the oversized frames has a hardware or software
error. It should be found and removed from the network.
Rx very long errors
Function: Shows the number of times that a frame longer than 6000 bytes (also called
"giants") has been received.
Significance: See "Rx long errors" above.
Rx jabber errors
Function: A jabber is a long frame with a CRC or alignment error.
Significance: See "Rx long errors" above.
Rx code violation errors
Function: Shows the number of illegal codes received by the port.
Significance: When using 100 Mbps links, each 4-bit code is transferred on the wire as a
5-bit code. This creates some illegal codes that should never be sent; if they are sent,
they are received and discarded as Code violations.
Rx overrun drops
Function: Shows there are more packets received than can be buffered.
Significance: The packet is then discarded.
Rx out of pools
Function: Shows there are no memory pools left because there are so many frames stored.
Significance: The port tries to cause collisions to increase the number of frames
rejected; this gives the pools time to empty.
Rx 2nd port drops
Function: Shows the number of packets discarded due to a MAC address moving to a new port
before its old filter entry has aged out.
Significance: The packet is discarded and the new position of the MAC address is learned.
Rx illegal MAC address drops
Function: Detects illegal source MAC addresses and discard them and count them.
Significance: IP multicast sources and 0.0.0.0 values are not allowed on the network. They
are not forwarded and are dropped.
Rx unsupported MAC frames
Function: Number of unsupported MAC control frames.
Significance:
Tx deferreds
Function: Shows the number of times the transmission of a frame is postponed due to
another frame already being transmitted on the Ethernet network.
Significance: This is a normal event on an Ethernet network. A high number of deferred
transmissions usually indicates good use of the bandwidth for the network segment.
Tx packets without link
Function: Shows the number of packets that have been sent without a link.
Significance: If a cable is removed from a port, some packets are lost before the port is
shut down (by the software). If a very large number of packets is measured, this may
indicate a problem with the software in the switch.
Link down events
Function: Shows the number of times that link pulses have failed to be detected.
Significance: Usually, this means that there are faults on the cable or that the cable has
been removed.
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