Troubleshooting Guide

Table 4—Explanation of CatOS show mac Command Counters
2
In-Discard and Lrn-Discard do not exist on all Catalyst platforms.
Table 5—Possible Causes for Incrementing CatOS Counters
Collisions configuration.
Late
Collisions
This is an indication of faulty hardware (NIC,
cable, or switch port) or a duplex mismatch.
Excessive
Collisions
This is an indication of overutilization of the
switch port at half-duplex or duplex mismatch.
Carrier
Sense
This is an indication of faulty hardware (NIC,
cable, or switch port).
Runts
This is an indication of the result of collisions,
duplex mismatch, IEEE 802.1Q (dot1q), or an
Inter-Switch Link Protocol (ISL) configuration
issue.
Giants
This is an indication of faulty hardware, dot1q, or
an ISL configuration issue.
Counter Description
Rcv-Unicast
This is an indication of the number of unicast
packets received.
Rcv-
Multicast
This is an indication of the number of multicast
packets received.
Rcv-
Broadcast
This is an indication of the number of broadcast
packets received.
Xmit-
Unicast
This is an indication of the number of unicast
packets transmitted.
Xmit-
Multicast
This is an indication of the number of multicast
packets transmitted.
Xmit-
Broadcast
This is an indication of the number of broadcast
packets transmitted.
Delay
Exceeded
This is an indication of the number of frames
discarded because of excessive delay in the
switching process.
MTU-Exced
This is an indication that one of the devices on
the port or segment transmits more than the
allowed frame size.
In-Discard
2
Count of valid frames received which were
discarded or filtered by the forwarding process.
Lrn-Discard
2
Packets which are forwarded and must not be
forwarded.
In-Lost
Packets which can not be received because the
input buffers are full.
Out-Lost
Packets which can not be transmitted because
the output buffers are full.
Counter Possible Cause
Delay
Exced
Severe problem with the switch. Create a service
request with Cisco
Technical Support.
MTU-
Exced
Verify ISL and dot1q configurations. Verify
another switch or router does not inject frame over
maximum transmission unit (MTU) into the switch
network.
Lrn-
Discard
2
Increments when the switch receives traffic on a
trunk for a specific VLAN while the switch does
not have any other ports on that VLAN. Counter
also increments when the destination address of
the packet is learned on the port on which the
packet is received.
Lrn-
Discard
2
This counter must remain at zero. If counter
increments, create a service request with Cisco