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Community Member

3750G-24TS interface drops

Hi experts,

I'm troubleshooting interface drops. However the output of the following show commands don't match number of drops. Based on the output, can you find out what is causing the drops? the G1/0/28 is the uplink. Is that just the port got overrun by the traffic? Any advice what I should do for the troubleshooting? Thanks!

#show int g1/0/28

GigabitEthernet1/0/28 is up, line protocol is up (connected)

  Hardware is Gigabit Ethernet, address is 0019.5667.191c (bia 0019.5667.191c)

  Description: Trunk to fmcceg18b

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

     reliability 255/255, txload 61/255, rxload 134/255

  Encapsulation ARPA, loopback not set

  Keepalive not set

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

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

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

  Last input 00:00:30, output 00:00:56, output hang never

  Last clearing of "show interface" counters 38w6d

  Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 514275

  Queueing strategy: fifo

  Output queue: 0/40 (size/max)

  5 minute input rate 526884000 bits/sec, 55855 packets/sec

  5 minute output rate 240349000 bits/sec, 44401 packets/sec

     707509920053 packets input, 661664102224812 bytes, 0 no buffer

     Received 694842094 broadcasts (559813073 multicasts)

     0 runts, 0 giants, 0 throttles

     1 input errors, 1 CRC, 0 frame, 0 overrun, 0 ignored

     0 watchdog, 559813073 multicast, 0 pause input

     0 input packets with dribble condition detected

     709036140028 packets output, 646024058356725 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

#sh mls qos int g1/0/28 statistics | be dropped

  output queues dropped:

queue:    threshold1   threshold2   threshold3


queue 0:           0           0           0

queue 1:   100516793        6492           1

queue 2:           0           0           0

queue 3:           0           0           0

Policer: Inprofile:            0 OutofProfile:            0

#sh platform port-asic stats drop g1/0/28

Switch : 1 :


  Interface Gi1/0/28 TxQueue Drop Statistics

    Queue 0

      Weight 0 Frames 0

      Weight 1 Frames 0

      Weight 2 Frames 0

    Queue 1

      Weight 0 Frames 100516793

      Weight 1 Frames 6492

      Weight 2 Frames 1

    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 0

Community Member

3750G-24TS interface drops

Without seeing your QOS policy, I am going to treat this like a physical problem. 

To rule out other issues, I would try swapping out to a new network cable.  I have been that fix other problems that couldnt be explained.  The port might be having a problem, although I dont see anything in what you post that would suggest that.  At a minimum, I would suggest moving to another port on the switch or better yet, a port controlled by a different ASIC.  Since you are on Gi1/0/28, I would move to the other end of the switch i.e. Gi1/0/10 or somewhere around there.  This will help eliminate or identify if the problem is with a particular port and/or ASIC.

Didnt initially catch you were on a port with an SFP.  Do you have a spare SFP that you can swap out to see if the SFP might be a problem ?  Something else worth trying is the hard code the port speed to 1000/Full. I have had a couple of times where hard coding the port (even on an SFP) made a different.  There is no explanation why it should but it has for me.  Do you have an open port where you can move the SFP to on that switch ?  Also, reseating the SFP might help resolve the problem.

If the ASIC is hung in a weird state, unplugging power to the switch, letting it sit for about 30 seconds to a minute and then plugging power might in might fix it.  Not trying to lead you down the wrong path, just trying to help.

Community Member

3750G-24TS interface drops

Hey Thanks Ronald. I will try what you suggested.

I just really don't understand why the two commands show different drop numbers. In the "show interface" output it shows the total number of drops but the sub-categories for the output errors are all 0. Is the number of drops relate to the "show mls qos interface xxx stats" in any way?


Community Member

3750G-24TS interface drops

Hi Ronald, another question, is there a command to show the input queue drops? The "show mls qos interface stats" doesn't show it... Thanks!

Community Member

3750G-24TS interface drops

Here is the command I use -

sh mls qos int int_name (i.e. gi1/0/1) statistics

As to why the two commands show different drop numbers, dont have an answer for you on that.  That is on my list to look at. Will probably take a call to TAC to get some info on that.  Havent found anything in the searching I have done.


Community Member

3750G-24TS interface drops

Thanks Ron. I will call Cisco TAC.

Community Member

3750G-24TS interface drops

You can use the option of  turning this thread into a TAC case.  From what I understand, we all can see the info on what the TAC engineers comes back with.  Also tells them that there are others interested in this same info.


Community Member

3750G-24TS interface drops

That's good to know Ron. However it might not be the case. We have the contract with IBM but not Cisco. We always contact IBM first for our problems. They only engage Cisco if they don't have the answer. Thanks for the advice though.

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