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Output drop on interface

rasmus.elmholt
Level 7
Level 7

Hi,

 

Our management station gives an notification about high output drops on interfaces.

After some debugging I have found the following information but am unsure what to make of it. And if this is an actual issue or just microbust drops.

This is on a Cat 9400 switch.

 

high amount of OQD on interface 1/0/22:

en02-abh022#show int summary 

 *: interface is up
 IHQ: pkts in input hold queue     IQD: pkts dropped from input queue
 OHQ: pkts in output hold queue    OQD: pkts dropped from output queue
 RXBS: rx rate (bits/sec)          RXPS: rx rate (pkts/sec)
 TXBS: tx rate (bits/sec)          TXPS: tx rate (pkts/sec)
 TRTL: throttle count

  Interface                   IHQ       IQD       OHQ       OQD      RXBS      RXPS      TXBS      TXPS      TRTL
-----------------------------------------------------------------------------------------------------------------
  GigabitEthernet1/0/18         0         0         0         0         0         0         0         0         0
  GigabitEthernet1/0/19         0         0         0    184456         0         0         0         0         0
* GigabitEthernet1/0/20         0         0         0     77949    213000        46    154000        44         0
  GigabitEthernet1/0/21         0         0         0      2701         0         0         0         0         0
* GigabitEthernet1/0/22         0         0         0     86482     68000        13    313000        39         0

No output errors on the interface:

#show interface GigabitEthernet1/0/22
GigabitEthernet1/0/22 is up, line protocol is up (connected) 
  Hardware is Gigabit Ethernet, address is 5c71.0d16.97f5 (bia 5c71.0d16.97f5)
  MTU 9100 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 
  Auto-MDIX on (operational: on)
  ARP type: ARPA, ARP Timeout 04:00:00
  Last input 00:01:28, output 00:00:01, output hang never
  Last clearing of "show interface" counters 2w5d
  Input queue: 0/375/0/0 (size/max/drops/flushes); Total output drops: 86494
  Queueing strategy: Class-based queueing
  Output queue: 0/40 (size/max)
  5 minute input rate 93000 bits/sec, 33 packets/sec
  5 minute output rate 702000 bits/sec, 80 packets/sec
     7541536 packets input, 4175452690 bytes, 0 no buffer
     Received 13989 broadcasts (11168 multicasts)
     0 runts, 0 giants, 0 throttles 
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
     0 watchdog, 11168 multicast, 0 pause input
     0 input packets with dribble condition detected
     13028188 packets output, 10316245654 bytes, 0 underruns
     Output 434509 broadcasts (0 multicasts)
     0 output errors, 0 collisions, 2 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

The service policy outgoing is showing default class drops:

#show policy-map interface GigabitEthernet1/0/22
 GigabitEthernet1/0/22 
  Service-policy output: ACCESS_OUT

<output omitted>

    Class-map: BULK-DATA (match-any)  
      0 packets
      Match:  dscp af13 (14)
      Queueing
      
      (total drops) 0
      (bytes output) 0
      bandwidth remaining 5%

    Class-map: class-default (match-any)  
      0 packets
      Match: any 
      Queueing
      
      (total drops) 131929956
      (bytes output) 9918062185
      bandwidth remaining 20%

taildropping:

#show platform hard fed active qos queue stats interface GigabitEthernet1/0/22 
----------------------------------------------------------------------------------------------
AQM Global counters
GlobalHardLimit:  9500   |   GlobalHardBufCount: 0
GlobalSoftLimit: 35476   |   GlobalSoftBufCount: 0

----------------------------------------------------------------------------------------------
High Watermark Soft Buffers:  Port Monitor Disabled
----------------------------------------------------------------------------------------------
Asic:0 Core:0 DATA Port:42 Hardware Enqueue Counters
----------------------------------------------------------------------------------------------
 Q Buffers          Enqueue-TH0          Enqueue-TH1          Enqueue-TH2             Qpolicer
   (Count)              (Bytes)              (Bytes)              (Bytes)              (Bytes)
-- ------- -------------------- -------------------- -------------------- --------------------
 0       0                    0            316867966             12289408                    0
 1       0                    0                    0             14246585                    0
 2       0                    0                    0                13536                    0
 3       0                    0                    0              8001743                    0
 4       0                    0                    0                    0                    0
 5       0                    0                    0           6732895248                    0
 6       0                    0                    0                    0                    0
 7       0                    0                    0                    0                    0
Asic:0 Core:0 DATA Port:42 Hardware Drop Counters
--------------------------------------------------------------------------------------------------------------------------------
 Q             Drop-TH0             Drop-TH1             Drop-TH2             SBufDrop              QebDrop         QpolicerDrop
                (Bytes)              (Bytes)              (Bytes)              (Bytes)              (Bytes)              (Bytes)
-- -------------------- -------------------- -------------------- -------------------- -------------------- --------------------
 0                    0                    0                    0                    0                    0                    0
 1                    0                    0                    0                    0                    0                    0
 2                    0                    0                    0                    0                    0                    0
 3                    0                    0                    0                    0                    0                    0
 4                    0                    0                    0                    0                    0                    0
 5                    0                    0             84117614                    0                    0                    0
 6                    0                    0                    0                    0                    0                    0
 7                    0                    0                    0                    0                    0                    0

How do I proceed in the tshoot from here?

3 Replies 3

Hello,

 

your first action to take with output drops would be to configure:

 

qos queue-softmax-multiplier 1200

 

in global configuration mode. Clear the counters and check if the output drops decrease...

Squozen_EU
Level 1
Level 1

This is confusing me, you're saying your class-default is dropping but I'm seeing class 5 being dropped. Just commenting so I can keep an eye on the thread and learn something.

As far as I can see most traffic is added to queue 5:

#show platform hardware fed active qos queue label2qmap qmap-egress-data interface gi 1/0/22 

Egress DATA Queue Mapping  -  Asic/Core/Port: 0/0/42

===============================================================================
Label   Q Threshold  VQ  |  Label   Q Threshold  VQ  |  Label   Q Threshold  VQ
===== === ========= ===  |  ===== === ========= ===  |  ===== === ========= ===
    0   5         2   2         1   5         2   2         2   5         2   2     
    3   5         2   2         4   5         2   2         5   5         2   2     
    6   5         2   2         7   5         2   2         8   5         2   2     
    9   5         2   2        10   5         2   2        11   5         2   2     
   12   5         2   2        13   5         2   2        14   5         2   2     
   15   4         2   2        16   5         2   2        17   5         2   2     
   18   5         2   2        19   3         2   2        20   5         2   2     
   21   5         2   2        22   5         2   2        23   5         2   2     
   24   5         2   2        25   2         2   2        26   5         2   2     
   27   2         2   2        28   5         2   2        29   2         2   2     
   30   5         2   2        31   2         2   2        32   5         2   2     
   33   1         2   2        34   5         2   2        35   1         2   2     
   36   5         2   2        37   1         2   2        38   5         2   2     
   39   1         2   2        40   5         2   2        41   5         2   2     
   42   5         2   2        43   5         2   2        44   5         2   2     
   45   5         2   2        46   5         2   2        47   0         1   2     
   48   5         2   2        49   5         2   2        50   5         2   2     
   51   5         2   2        52   5         2   2        53   5         2   2     
   54   5         2   2        55   5         2   2        56   5         2   2     
   57   5         2   2        58   5         2   2        59   5         2   2     
   60   5         2   2        61   5         2   2        62   5         2   2     
   63   5         2   2        64   5         2   2        

https://people.ucsc.edu/~warner/Bufs/9000-QoS-and-Queuing.pdf

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