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Since I can remember I have upload bandwidth issues with only a spécific partner of our company and I'm still investigating why ...

I noticed some strange behaviour concerning the traffic control on the main network interface and asking myself if it should be the origin of my problem.

Here is the return of the "/sbin/tc -s -d class show dev eth0" command that show a huge number of dropped packet only on the 9th queue (no dropped packets for the other queues) :

class mq :9 root Sent 740545290948 bytes 870754148 pkt (dropped 35373, overlimits 0 requeues 30919) backlog 0b 0p requeues 30919

Could someone please explain to me precisely what It means and how I can correct this if It is a problem ?

Many Thanks !

  • Given you've sent over 870 million packets, 35000 dropped packets is a tiny, tiny fraction. Why is this even a concern? – Matthew Ife May 23 '17 at 9:42
  • The thing is I don't really know if this is a concern since I'm not a Linux Networking expert :) but as I have explained we have a bandwidth issue with only one server of our partner (TCP session limited to around 10Mb/s for upload) but no traffic control or iptable rules which can explain this limitation ... – Benj74 May 23 '17 at 9:53
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Packets drop can cause troubles like noticeable delays or low speed. This depends on the application and the drop percentage.

Traffic control is done usually by delaying packets when the allowed rate is exceeded. Delaying packets means to queue them. A queue has a limit of how many packets it can accommodate. When exceeding the rate for a long duration, a packet queue can get filled and start dropping packets.

To resolve this, you can try several options like:

  • Increase allowed rate for affected user(s).
  • Increase queue/buffer size.
  • Lower application/user traffic rate if applicable.

To confirm whether this is causing troubles to you or not, you can temporarily disable traffic shaping (if possible) and check the result.

  • Thank you for your answer, I'll try to disable the traffic shaping and see If the issue still occurs (I already increased the buffer size with no effect) – Benj74 May 23 '17 at 9:57

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