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Total output drops


Hi @all 


6 Month ago we changed your switches from 2960 to 2960x. The 2960x are connected as a stack with max 6 switches and a uplink of 2*10GBit Etherchannel. Since we changed the hardware we have the issue that at the access ports have output drops. I have no idea why this happend and how i can fix this problem. Any idea ?


GigabitEthernet5/0/40 is up, line protocol is up (connected)
  Hardware is Gigabit Ethernet, address is 189c.5dd8.22a8 (bia 189c.5dd8.22a8)
  MTU 1500 bytes, BW 1000000 Kbit/sec, 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 00:00:03, output hang never
  Last clearing of "show interface" counters never
  Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 1988762
  Queueing strategy: fifo
  Output queue: 0/40 (size/max)
  5 minute input rate 202000 bits/sec, 61 packets/sec
  5 minute output rate 245000 bits/sec, 68 packets/sec
     500131403 packets input, 182892336075 bytes, 0 no buffer
     Received 424177 broadcasts (256028 multicasts)
     0 runts, 0 giants, 0 throttles
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
     0 watchdog, 256028 multicast, 0 pause input
     0 input packets with dribble condition detected
     593398679 packets output, 201759850373 bytes, 0 underruns
     0 output errors, 0 collisions, 1 interface resets
     0 unknown protocol drops
     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


Gi5/0/40                     connected    217        a-full a-1000 10/100/1000BaseTX


Switch Ports Model              SW Version            SW Image
------ ----- -----              ----------            ----------
     1 52    WS-C2960X-48TD-L   15.0(2)EX4            C2960X-UNIVERSALK9-M
     2 52    WS-C2960X-48TD-L   15.0(2)EX4            C2960X-UNIVERSALK9-M
     3 52    WS-C2960X-48TD-L   15.0(2)EX4            C2960X-UNIVERSALK9-M
     4 52    WS-C2960X-48TD-L   15.0(2)EX4            C2960X-UNIVERSALK9-M
     5 52    WS-C2960X-48TD-L   15.0(2)EX4            C2960X-UNIVERSALK9-M
*    6 52    WS-C2960X-48TD-L   15.0(2)EX4            C2960X-UNIVERSALK9-M

8 Replies 8

InayathUlla Sharieff
Cisco Employee
Cisco Employee

Hi Mario,

What is connected at the other end?

1-Can you clear the counters and check how often the drops are increasing?

2- Also check if there is any burst traffic happening which is causing the output drops to get increase?

3- Is QOS enabled on the box?

4- Can you try changing the port and put the port on different ASIC?




Hi insharie

The end device is a Windows 7 client HP 6000 Pro

1 I will monitor the counter and tell you when he will increase

2 We will analyze

3 QoS is not enabled

4 This behavior is on different Ports and Switches at the Stack


interface GigabitEthernet5/0/40
 description Test Gi5/0/40
 switchport mode access
 authentication host-mode multi-host
 authentication port-control auto
 authentication periodic
 authentication timer reauthenticate 7200
 authentication violation protect
 dot1x pae authenticator
 dot1x timeout quiet-period 1
 dot1x timeout tx-period 5
 dot1x max-reauth-req 3
 spanning-tree portfast