Recently I went through troubleshooting of Site-to-Site Layer-2 link. One of the things we did during troubleshooting of that link was checking interface statistics for interfaces which were connecting two geographical sites together.
Below quick overview how ot check and reset port statistics if required during troubleshooting process.
Switch#sh int fa0/43
FastEthernet0/43 is up, line protocol is up (connected)
Hardware is Fast Ethernet, address is 001f.2702.9baf (bia 001f.2702.9baf)
Description: ### Layer-2 100Mb/s link between sites ###
MTU 1500 bytes, BW 100000 Kbit, DLY 100 usec,
reliability 255/255, txload 1/255, rxload 43/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Half-duplex, 100Mb/s, media type is 10/100BaseTX
input flow-control is off, output flow-control is unsupported
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:00:03, output 00:00:01, output hang never
Last clearing of "show interface" counters 00:38:50
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 17125000 bits/sec, 1437 packets/sec
5 minute output rate 766000 bits/sec, 1240 packets/sec
2664490 packets input, 3972786136 bytes, 0 no buffer
Received 376 broadcasts (343 multicasts)
0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
0 watchdog, 343 multicast, 0 pause input
0 input packets with dribble condition detected
2306375 packets output, 179418342 bytes, 0 underruns
0 output errors, 239619 collisions, 0 interface resets
0 babbles, 3292 late collision, 0 deferred
0 lost carrier, 0 no carrier, 0 PAUSE output
0 output buffer failures, 0 output buffers swapped out
Switch#clear counters fa0/43
Clear "show interface" counters on this interface [confirm]
Switch#sh int fa0/43
FastEthernet0/43 is up, line protocol is up (connected)
Hardware is Fast Ethernet, address is 001f.2702.9baf (bia 001f.2702.9baf)
Description: ### Layer-2 100Mb/s link between sites ###
MTU 1500 bytes, BW 100000 Kbit, DLY 100 usec,
reliability 255/255, txload 1/255, rxload 43/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Half-duplex, 100Mb/s, media type is 10/100BaseTX
input flow-control is off, output flow-control is unsupported
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:00:05, output 00:00:00, output hang never
Last clearing of "show interface" counters 00:00:04
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 17013000 bits/sec, 1426 packets/sec
5 minute output rate 770000 bits/sec, 1237 packets/sec
5907 packets input, 8813408 bytes, 0 no buffer
Received 0 broadcasts (0 multicasts)
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
4943 packets output, 381064 bytes, 0 underruns
0 output errors, 476 collisions, 0 interface resets
0 babbles, 5 late collision, 0 deferred
0 lost carrier, 0 no carrier, 0 PAUSE output
0 output buffer failures, 0 output buffers swapped out
Switch#