output drops dilemma on cisco 2960

[Gsiaw]

I'm having out put drops on ths interface which is an access port connected to a server.

I  removed the server and connected it directly to the host using a crossover cable and there was no packet drops, can anyone explain to me why that is the case? Evry interface in my network is 1G/full duplex

GigabitEthernet1/0/37 is up, line protocol is up

  Hardware is Gigabit Ethernet, address is b4a4.e323.b325 (bia b4a4.e323.b325)

  MTU 1500 bytes, BW 1000000 Kbit, DLY 10 usec,

     reliability 255/255, txload 1/255, rxload 1/255

  Encapsulation ARPA, loopback not set

  Keepalive set (10 sec)

  Full-duplex, 1000Mb/s, media type is 10/100/1000BaseTX

  input flow-control is off, output flow-control is unsupported

  ARP type: ARPA, ARP Timeout 04:00:00

  Last input never, output 00:38:23, output hang never

  Last clearing of "show interface" counters 01:42:55

  Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 3515

  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

     208452 packets input, 193401616 bytes, 0 no buffer

     Received 20767 broadcasts (20765 multicasts)

     0 runts, 0 giants, 0 throttles

     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored

     0 watchdog, 20765 multicast, 0 pause input

     0 input packets with dribble condition detected

     8428681 packets output, 11181884258 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

[paolo bevilacqua]

They are not enough to worry about.

Anyway, if you have any QoS configuration, try removing it.

[Joseph W. Doherty]

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Posting

Most likely you have transient congestion.  Consider if more than one gig ports sends to the same destination gig port, the latter will queue the excess.  If there's enough excess it will overflow the queue and be counted as drops.

If the congestion is transient, which would seem to be the case since your dropped packets percentage is about .04% (which is why Paolo is telling you not to worry about them), increasing your queue buffer should reduce or eliminate the few drops you're seeing.

Oh, and why one host on the connection has drops versus a different host, because usually different hosts make different traffic demands.  If you just move you server to another port on the same switch, assuming the port is configured the same as the original port, you'll likely get the same results.