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jpd
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Joined: Fri Oct 22, 2021 3:19 pm

CRS326-24G-2S+ - Incrementing tx-drop counter on Ethernet Interface

Sat Nov 20, 2021 3:45 pm

I notice the tx-drop counter slowly incrementing on the ethernet interface of my CRS326 running ROS/firmware 6.49.1.
To be clear, I am not experiencing any performance issues or packet loss.
I am trying to understand why I am seeing the tx-drop counter increment when I should be nowhere near exhausting the output queue on interfaces that show incrementing drops.

I am using the CRS326 as a pure switch with all interfaces bridged and HW offloaded. Flow control is disabled.
My configuration is near to default and I am not using VLANs or L3 features that would cause packets to be processed by the CPU.
I am not using any 10G --> 1G connections (or any 10G at all) where tx buffer exhaustion would make sense.
iperf testing shows ~942 Mbits/sec with 0 retries.
The interface statistics on other connected devices are not showing errors/drops or any signs of buffer exhaustion.

Again I realize these are minimal drops and they are not causing any noticeable impact but I can't help but wonder if anyone else is seeing the same behavior? The only other examples I've been able find involve 10G --> 1G connections.
Are these drops cosmetic or the result of receiving unknown frames? I am new to Mikrotik is this simply normal operation?
I would love to hear your thoughts.

ether1 and ether2 have 100M devices connected and show no drops.
ether 23 is an uplink to an AP that doesn't see anywhere near gigabit speeds.
ether 22 is an uplink to a HEX POE with 2 100M devices connected.
interface ethernet print stats where running 

                 name:      ether1     ether2         ether3        ether4         ether5        ether6     ether22        ether23        ether24
       driver-rx-byte:           0      9 118      1 299 564     1 026 820      2 533 185     1 472 903  57 886 412     19 888 680        388 600
     driver-rx-packet:           0         26          8 640         3 011         17 814         7 050     872 881         49 012          3 203
       driver-tx-byte:   5 283 480  5 283 822      5 283 480     5 288 280      5 283 420     5 561 939 236 710 706      5 283 480      5 314 190
     driver-tx-packet:      88 058     88 059         88 058        88 139         88 057        86 292   1 115 906         88 058         88 299
             rx-bytes:  17 830 748  1 058 635    155 493 398   849 493 753  5 461 479 885   598 833 315 292 399 862    655 984 315 57 955 664 678
         rx-too-short:           0          0              0             0              0             0           0              0              0
          rx-too-long:           0          0              0             0              0             0           0              0              0
           rx-unicast:     170 302      6 403      1 232 356     1 774 440      4 350 438     3 173 140   1 779 585      2 861 246     44 973 387
         rx-broadcast:           0         15            585            80            118           104         400         26 067          1 873
             rx-pause:           0          0              0             0              0             0           0              0              0
         rx-multicast:           0         29          7 997         2 978         17 700         6 434          15         22 961              0
      rx-error-events:           0          0              0             0              0             0           0              0              0
         rx-fcs-error:           0          0              0             0              0             0           0              0              0
          rx-fragment:           0          0              0             0              0             0           0              0              0
          rx-overflow:           0          0              0             0              0             0           0              0              0
            rx-jabber:           0          0              0             0              0             0           0              0              0
             tx-bytes:  47 761 263 32 265 440 25 157 341 203 3 433 928 019 14 216 255 134 9 131 701 327 368 331 713 11 659 578 008  2 346 667 495
           tx-unicast:     171 167      7 421     16 989 856     4 609 948     10 525 156     7 976 629   1 894 969     10 074 168      8 233 946
         tx-broadcast:      29 387     29 375         28 804        29 310         29 271        28 406      28 924          3 328         27 530
             tx-pause:           0          0              0             0              0             0           0              0              0
         tx-multicast:     143 174    143 161        135 177       143 100        125 480       133 149     143 089        120 220        143 173
          tx-underrun:           0          0              0             0              0             0           0              0              0
         tx-collision:           0          0              0             0              0             0           0              0              0
    tx-late-collision:           0          0              0             0              0             0           0              0              0
              tx-drop:           0          0             18             2             12             9           3             14             14
             tx-rx-64:      94 970    100 944        112 607       242 526        208 367       219 723     132 619        342 563        681 287
         tx-rx-65-127:     355 926     21 585      1 471 654     1 308 899      1 226 688     2 772 267   1 825 603      3 230 494      7 605 087
        tx-rx-128-255:      40 902     40 902        127 360     1 086 930        102 804     1 446 594     702 219        792 801      2 965 937
        tx-rx-256-511:       4 173      4 080         41 806       663 127         72 301       527 712   1 099 211        402 034      1 142 362
       tx-rx-512-1023:      17 981     18 391        101 856       975 377         79 884       155 888      65 969        268 448      1 410 272
       tx-rx-1024-max:          78        502     16 539 492     2 282 997     13 358 119     6 195 678      21 361      8 071 650     39 574 964
     tx-queue0-packet:     343 728    179 957     17 153 819     4 782 356     10 679 895     8 138 175   2 066 979     10 197 702      8 404 635
     tx-queue1-packet:           0          0              0             0              0             0           0              0              0
     tx-queue2-packet:           0          0              0             0              0             0           0              0              0
     tx-queue3-packet:           0          0              0             0              0             0           0              0              0
     tx-queue4-packet:           0          0              0             0              0             0           0              0              0
     tx-queue5-packet:           0          0              0             0              0             0           0              0              0
     tx-queue6-packet:           0          0              0             0              0             0           0              0              0
     tx-queue7-packet:           0          0              0             0              0             0           0              0              0
 
jpd
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Joined: Fri Oct 22, 2021 3:19 pm

Re: CRS326-24G-2S+ - Incrementing tx-drop counter on Ethernet Interface

Sat Nov 27, 2021 1:06 am

Anyone else seeing drops? Anyone care to share their stats? Thanks!
 
joshhboss
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Posts: 273
Joined: Thu Aug 01, 2019 2:13 pm

Re: CRS326-24G-2S+ - Incrementing tx-drop counter on Ethernet Interface

Sun Jan 14, 2024 4:32 am

Im seeing this and still dont understand why.
I think I found the same post on reddit that you posted.. I replied to that one as well

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