[Bloat] [bbr-dev] Re: Are we heading towards a BBR-dominant Internet?

[Bob McMahon]

Hi Neal,

These look like steady-state bulk flow tests unless I'm missing something.

Bob

On Sun, Aug 28, 2022 at 11:43 AM Neal Cardwell <ncardwell at google.com> wrote:

> Sure. For testing these kinds of properties of the BBR algorithm we use
> various transperf test cases. The transperf tool is something Soheil Hassas
> Yeganeh and our team cooked up and open-sourced here:
>
>   https://github.com/google/transperf
>
> Best regards,
> neal
>
> On Sat, Aug 27, 2022, 4:43 PM Bob McMahon <bob.mcmahon at broadcom.com>
> wrote:
>
>> Curious to what you're doing during development, if you can share?
>>
>> Thanks,
>> Bob
>>
>> On Sat, Aug 27, 2022 at 7:44 AM Neal Cardwell <ncardwell at google.com>
>> wrote:
>>
>>> Hi Bob,
>>>
>>> Good question. I can imagine a number of different techniques to
>>> generate and measure the traffic flows for this kind of study, and don't
>>> have any particular suggestions.
>>>
>>> neal
>>>
>>>
>>> On Fri, Aug 26, 2022 at 4:54 PM Bob McMahon <bob.mcmahon at broadcom.com>
>>> wrote:
>>>
>>>> Hi Neal,
>>>>
>>>> Any thoughts on tooling to generate and measure the traffic flows BBR
>>>> is designed to optimize? I've been adding some low duty cycle support in iperf
>>>> 2 <https://sourceforge.net/projects/iperf2/> with things like --bounceback
>>>> and --burst-period and --burst-period
>>>> <https://iperf2.sourceforge.io/iperf-manpage.html>. We could pull the
>>>> size and period from a known distribution or distributions though not sure
>>>> what to pick.
>>>>
>>>> Thanks,
>>>> Bob
>>>>
>>>> Bob
>>>>
>>>> On Fri, Aug 26, 2022 at 6:36 AM 'Neal Cardwell' via BBR Development <
>>>> bbr-dev at googlegroups.com> wrote:
>>>>
>>>>> Yes, I agree the assumptions are key here. One key aspect of this
>>>>> paper is that it focuses on the steady-state behavior of bulk flows.
>>>>>
>>>>> Once you allow for short flows (like web pages, RPCs, etc) to
>>>>> dynamically enter and leave a bottleneck, the considerations become
>>>>> different. As is well-known, Reno/CUBIC will starve themselves if new flows
>>>>> enter and cause loss too frequently. For CUBIC, for a somewhat typical 30ms
>>>>> broadband path with a flow fair share of 25 Mbit/sec, if new flows enter
>>>>> and cause loss more frequently than roughly every 2 seconds then CUBIC will
>>>>> not be able to utilize its fair share. For a high-speed WAN path, with
>>>>> 100ms RTT and fair share of 10 Gbit/sec,  if new flows enter and cause loss
>>>>> more frequently than roughly every 40 seconds then CUBIC will not be able
>>>>> to utilize its fair share. Basically, loss-based CC can starve itself in
>>>>> some very typical kinds of dynamic scenarios that happen in the real world.
>>>>>
>>>>> BBR is not trying to maintain a higher throughput than CUBIC in these
>>>>> kinds of scenarios with steady-state bulk flows. BBR is trying to be robust
>>>>> to the kinds of random packet loss that happen in the real world when there
>>>>> are flows dynamically entering/leaving a bottleneck.
>>>>>
>>>>> cheers,
>>>>> neal
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> On Thu, Aug 25, 2022 at 8:01 PM Dave Taht via Bloat <
>>>>> bloat at lists.bufferbloat.net> wrote:
>>>>>
>>>>>> I rather enjoyed this one. I can't help but wonder what would happen
>>>>>> if we plugged some different assumptions into their model.
>>>>>>
>>>>>> https://www.comp.nus.edu.sg/~bleong/publications/imc2022-nash.pdf
>>>>>>
>>>>>> --
>>>>>> FQ World Domination pending:
>>>>>> https://blog.cerowrt.org/post/state_of_fq_codel/
>>>>>> Dave Täht CEO, TekLibre, LLC
>>>>>> _______________________________________________
>>>>>> Bloat mailing list
>>>>>> Bloat at lists.bufferbloat.net
>>>>>> https://lists.bufferbloat.net/listinfo/bloat
>>>>>>
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>>>>>
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