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

[Bob McMahon]

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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