Interface Output Drops

[waelkuku1]

A large number of output drops seen on interface gi1/0/2 of a 3750 (12.2.52SE code). The output of show buffers show misses in the big buffers pool
more than others.

Additionally, the port-asic indicate the drops are seen on queue 3 weight 2.

C3750SW#show platform port-asic stats drop gi1/0/2
  Interface Gi1/0/2 TxQueue Drop Statistics
    Queue 0
      Weight 0 Frames 0
      Weight 1 Frames 0
      Weight 2 Frames 0
    Queue 1
      Weight 0 Frames 0
      Weight 1 Frames 0
      Weight 2 Frames 0
    Queue 2
      Weight 0 Frames 0
      Weight 1 Frames 0
      Weight 2 Frames 0
    Queue 3
      Weight 0 Frames 0
      Weight 1 Frames 0
      Weight 2 Frames 4890392278
    Queue 4
      Weight 0 Frames 0
      Weight 1 Frames 0
      Weight 2 Frames 0
    Queue 5
      Weight 0 Frames 0
      Weight 1 Frames 0
      Weight 2 Frames 0
    Queue 6
      Weight 0 Frames 0
      Weight 1 Frames 0
      Weight 2 Frames 0
    Queue 7
      Weight 0 Frames 0
      Weight 1 Frames 0
      Weight 2 Frames 0

The interface is configured as a simple trunk with no qos. Qos is disabled on the switch. Please advise.

[Leo Laohoo]

Post the outputs to the following commands:

1.  sh interface G1/0/2; and

2.  sh controll e G1/0/2

What is the downstream client connected to G1/0/2?

[waelkuku1]

This is connected to a 5540 firewall.

C3750SW#show interfaces gi1/0/2
GigabitEthernet1/0/2 is up, line protocol is up (connected)
 
  MTU 1500 bytes, BW 1000000 Kbit, DLY 10 usec,
     reliability 255/255, txload 3/255, rxload 2/255
  Encapsulation ARPA, loopback not set
  Keepalive set (10 sec)
  Full-duplex, 1000Mb/s, media type is 10/100/1000BaseTX
  Media-type configured as  connector
  input flow-control is off, 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 3w2d
  Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 1313535582
  Queueing strategy: fifo
  Output queue: 0/40 (size/max)
  5 minute input rate 9614000 bits/sec, 2383 packets/sec
  5 minute output rate 12497000 bits/sec, 2566 packets/sec
     6105336989 packets input, 1614083141590 bytes, 0 no buffer
     Received 244575 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
     7205145488 packets output, 7034809165681 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

C3750SW#show controllers ethernet-controller gi1/0/2

     Transmit GigabitEthernet1/0/2            Receive
   2664455946 Bytes                       2233866474 Bytes                   
   1723888415 Unicast frames               317141734 Unicast frames          
    489964070 Multicast frames                     0 Multicast frames        
   1101267501 Broadcast frames              12072954 Broadcast frames        
            0 Too old frames              1036440334 Unicast bytes           
            0 Deferred frames                      0 Multicast bytes         
            0 MTU exceeded frames          772681100 Broadcast bytes         
            0 1 collision frames                   0 Alignment errors        
            0 2 collision frames                   0 FCS errors              
            0 3 collision frames                   0 Oversize frames         
            0 4 collision frames                   0 Undersize frames        
            0 5 collision frames                   0 Collision fragments     
            0 6 collision frames      
            0 7 collision frames          2347401033 Minimum size frames     
            0 8 collision frames          2365748755 65 to 127 byte frames   
            0 9 collision frames          4233529917 128 to 255 byte frames  
            0 10 collision frames          381094442 256 to 511 byte frames  
            0 11 collision frames         3319510542 512 to 1023 byte frames 
            0 12 collision frames          566742965 1024 to 1518 byte frames
            0 13 collision frames                  0 Overrun frames          
            0 14 collision frames                  0 Pause frames            
            0 15 collision frames     
            0 Excessive collisions                 0 Symbol error frames     
            0 Late collisions                      0 Invalid frames, too large
            0 VLAN discard frames              88922 Valid frames, too large 
            0 Excess defer frames                  0 Invalid frames, too small
     11357188 64 byte frames                       0 Valid frames, too small 
   3789923036 127 byte frames         
    576873664 255 byte frames                      0 Too old frames          
    197688862 511 byte frames                      0 Valid oversize frames   
   3519012209 1023 byte frames                     0 System FCS error frames 
   3810199534 1518 byte frames                     0 RxPortFifoFull drop frame
           85 Too large frames        
            0 Good (1 coll) frames    
            0 Good (>1 coll) frames   

[Leo Laohoo]

I don't see any line issues.

Two potential things:

1.  IOS bug:  Possibly.  I wouldn't recommend anyone running the IOS your switch is currently using.  If you ask me, I'd recommend 12.2(55)SE8.

2.  Switch buffer overflow:  High possibility.  Catalyst switch are known to have very shallow memory buffer.  High speed servers, for example, if connected without any QoS will exhibit high output drops.  You could test this by downgrading the speed of the switchport to 100 Mbps, using the command "speed auto 100", and see if output drops increment.  If they don't then you'll need to enable QoS.  Don't forget to put the speed up to 1 Gbps when you're done testing.