Buffer Bloat Mitigation w/o speed impact?

  • Has anyone been able to successfully implement buffer bloat mitigation without it having a considerable impact on overall performance?

    I have a business-class cable connection that offers 400 down and 20 up. Without any Codel settings enabled, such as the tutorial on YouTube from Lawrence Systems, I get those speeds. But, if I implement codel settings, the buffer bloat grade from dslreports speedtest goes from a "C" to an "A" but my download speed drops from 400-450 to less than 100.

    I had a lengthy exchange with Netgate support (as I have a contract) and they could never help me tweak it to the point where it did not have a dramatic performance hit.

    Just curious if anyone else was successful in doing so, and if so, what settings did you use?



  • Hi @StarsAndBars - could you please post some screenshots of how you have your limiters configured? Also, what are the specifications of your pfSense box, including make and model of NIC(s) you are using?

    There is a lengthy thread in the Traffic Shaping forum on fq-codel which includes a lot of great information on configuration and tuning. Check out this post to get started:


    Hope this helps.

  • Make and model of modem as well please?

  • Also, checkout the Hangout from Aug 2018 and related slides (5-11)...

    I have the same ISP speeds, followed slides 5 - 11 and have zero problems.

  • LAYER 8 Netgate

    So you either get 400/20 with buffer bloat or you get 100Mbit/sec downloads?

    Buffer bloat is pretty much exclusively caused by uploading faster than the ISP can handle so they buffer.

    You should not be doing anything with your downloads that will affect buffer bloat.

    Buffer bloat is pretty much exclusively an ISP problem. Have you talked to them about why you can't get the 400/20 you are paying for without a "C" grade? Have they implemented CODEL in their infrastructure?

  • @tman222 Thank you for the info! I appreciate it.

    The pfSense box is generic, built off of a Supermicro E300 motherboard. It has 8 cores and 32GB of RAM (yes, I know... I went big). It is running off a pair of 16GB SSDs on ZFS in RAID.

    As far as the interfaces, it is using 2 of the provided SFP+ ports. They have 10GbE copper transceivers in them. Even though the ISP only offers 1GbE copper ports on the cable modem, I wanted to be ready for the future, and I have 10GbE switching on the LAN. The remainder of the (currently unused) ports are 1GbE copper from Intel.

    I will go review the thread you linked. Thank you again!

  • @chpalmer Thanks for your response. The Cable Modem provided by the ISP is a Hitronic CGNM-2250 and as it is a business-class account, I do not have the luxury of selecting my own.

  • @Derelict I understand what you are saying, but riddle me this:

    If I leave the default pfSense rules in place (or lack thereof) and make no changes whatsoever to the limiter/floating rules, I get the full speed available from the ISP, about 400 down, and 20 up. The speedtest from dslreports grades the buffer bloat at a "C" and I saw buffer bloat recorded as high as 243ms.

    If I enable the buffer bloat mitigation as supplied by Netgate support, the speed from the ISP falls to just under 100 down, the upload stays at about 20, but there is no real buffer bloat observed and dslreports gives it a grade of "A"

    So, it seems to me as if the parameters around buffer boat are somewhat within my control, it just depends on if I can tolerate the huge penalty in download speed encountered to eliminate buffer bloat.

    This leads me to believe that there are settings I can tweak, or even a different algo to use (cake, perhaps?) that would resolve this. Finding the right mix will be the challenge.

  • @StarsAndBars try enabling PowerD under System / Advanced / Miscellaneous and set it to maximum.

  • @StarsAndBars You never have said what your limiters are set to. Can you post screenshots of how you have it setup?

  • @StarsAndBars said in Buffer Bloat Mitigation w/o speed impact?:

    @chpalmer Thanks for your response. The Cable Modem provided by the ISP is a Hitronic CGNM-2250 and as it is a business-class account, I do not have the luxury of selecting my own.

    Since this is a Puma6 model modem keep in mind that it has some issues.. http://badmodems.com/

    Make sure you have no UDP traffic going on while you are testing.. Some modems have various patches in place but depending on the ISP some do not.. UDP traffic can be quite the problem for these modems to handle.. VOIP, video, gaming ect..

    If you are a Comcast customer then the only reason they will not let you use your own modem as a commercial customer is if you have purchased static IP's from them. Otherwise we do it all the time. I would bring up the Badmodems site to your ISP and see if they will give you another Broadcom based model..

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