You can view the counters for a port on a Cisco switch using the
show interfaces command. E.g., if I want to check on whether
cyclic redundancy check (CRC) errors have been occurring on port fa0/16,
I can issue the command shown below:
Huron>show interfaces fa0/16
FastEthernet0/16 is up, line protocol is up (connected)
Hardware is Fast Ethernet, address is 0009.e897.d290 (bia 0009.e897.d290)
MTU 1500 bytes, BW 10000 Kbit, DLY 1000 usec,
reliability 255/255, txload 19/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Full-duplex, 10Mb/s, media type is 100BaseTX
input flow-control is unsupported output flow-control is unsupported
ARP type: ARPA, ARP Timeout 04:00:00
Last input never, output 00:00:00, output hang never
Last clearing of "show interface" counters 2d17h
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: fifo
Output queue: 0/40 (size/max)
5 minute input rate 24000 bits/sec, 40 packets/sec
5 minute output rate 756000 bits/sec, 64 packets/sec
46168 packets input, 4608074 bytes, 0 no buffer
Received 1250 broadcasts (1161 multicast)
0 runts, 0 giants, 0 throttles
121 input errors, 16 CRC, 105 frame, 0 overrun, 0 ignored
0 watchdog, 1161 multicast, 0 pause input
0 input packets with dribble condition detected
255151 packets output, 119141892 bytes, 0 underruns
0 output errors, 0 collisions, 0 interface resets
0 babbles, 0 late collision, 0 deferred
0 lost carrier, 0 no carrier, 0 PAUSE output
0 output buffer failures, 0 output buffers swapped out
Huron>I can see that 16 CRC errors have occurred since the counters for this port were last reset 2 days and 17 hours ago. I can tell the counters for the port were reset that long ago from the line below that appears in the output of the "show interface" command.
Last clearing of "show interface" counters 2d17h
I can reset the counters by entering
privileged EXEC mode by isssuing the enable command. I can
then clear the counters for just the one particular port by the command
clear counters port_designator. When you enter the
command you will be prompted to confirm that you wish the counters
on the interface to be reset. You can enter y to confirm that
you wish that action taken. E.g.:
Huron>enable
Password:
Huron#clear counters fa0/16
Clear "show interface" counters on this interface [confirm]y
Huron#show interface fa0/16
FastEthernet0/16 is up, line protocol is up (connected)
Hardware is Fast Ethernet, address is 0009.e897.d290 (bia 0009.e897.d290)
MTU 1500 bytes, BW 10000 Kbit, DLY 1000 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Full-duplex, 10Mb/s, media type is 100BaseTX
input flow-control is unsupported output flow-control is unsupported
ARP type: ARPA, ARP Timeout 04:00:00
Last input never, output 00:00:01, output hang never
Last clearing of "show interface" counters 00:01:27
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: fifo
Output queue: 0/40 (size/max)
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
0 packets input, 0 bytes, 0 no buffer
Received 0 broadcasts (0 multicast)
0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
0 watchdog, 0 multicast, 0 pause input
0 input packets with dribble condition detected
80 packets output, 7161 bytes, 0 underruns
0 output errors, 0 collisions, 0 interface resets
0 babbles, 0 late collision, 0 deferred
0 lost carrier, 0 no carrier, 0 PAUSE output
0 output buffer failures, 0 output buffers swapped out
Huron#In addition to resetting the error counters, the clear counters
command also resets the input and output counters.
Huron>show interfaces fa0/16 counters Port InOctets InUcastPkts InMcastPkts InBcastPkts Fa0/16 386867 1624 294 21 Port OutOctets OutUcastPkts OutMcastPkts OutBcastPkts Fa0/16 2527937 2352 671 39 Huron>enable Password: Huron#clear counters fa0/16 Clear "show interface" counters on this interface [confirm]y Huron#show interfaces fa0/16 counters Port InOctets InUcastPkts InMcastPkts InBcastPkts Fa0/16 0 0 0 0 Port OutOctets OutUcastPkts OutMcastPkts OutBcastPkts Fa0/16 192 0 3 0 Huron#