Re: [aqm] [tcpm] TCP ACK Suppression

Joe Touch <touch@isi.edu> Fri, 09 October 2015 22:39 UTC

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To: David Lang <david@lang.hm>
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From: Joe Touch <touch@isi.edu>
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Date: Fri, 9 Oct 2015 15:39:10 -0700
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Cc: "tcpm@ietf.org" <tcpm@ietf.org>, touch@isi.edu, "mallman@icir.org" <mallman@icir.org>, "LAUTENSCHLAEGER, Wolfram \(Wolfram\)" <wolfram.lautenschlaeger@alcatel-lucent.com>, Greg White <g.white@CableLabs.com>, "aqm@ietf.org" <aqm@ietf.org>
Subject: Re: [aqm] [tcpm] TCP ACK Suppression
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On 10/9/2015 3:31 PM, David Lang wrote:
> On Fri, 9 Oct 2015, Joe Touch wrote:
> 
>> On 10/9/2015 3:16 PM, David Lang wrote:
>> ...
>>>> Wouldn't it have been cleaner with more appropriate network
>>>> provisioning?
>>>
>>> "more appropriate network provisioning" is not always going to result in
>>> more bandwidth the way you want it to.
>>>
>>> If there is established infrastructure that can handle X in one
>>> direction and 100X in the other direction, but "appropriate network
>>> provisioning" requires that the ratio never be more than 3x, it's not
>>> going to magically increase bandwidth in one direction, all it can do is
>>> cap bandwidth in the other direction (throwing away capacity)
>>
>> Sure, but we're dealing with a problem that arises when the ratio can't
>> support 40:1. That's quite an asymmetry except in extreme cases where we
>> already know extreme measures are required (e.g., satcom with telco
>> backchannels).
> 
> that's not the only situation we're talking about here.
> 
> Also, keep in mind that your 40:1 ratio assumes that there is no traffic
> going the other direction.

FWIW, I wasn't - I was assuming that 40:1 is fine if what you intend to
support is browsing only.

> If you have one person trying to watch streaming video while another
> person is uploading pictures to facebook, you can run into trouble at
> much more even ratios.

Restated, you run into trouble because you sold a service you didn't
provision for ;-)

(or, more to the point, you took a gamble that you could sell a useful
service with a particular assumption about traffic ratios, and that
assumption no longer holds)

Again, IMO TCP isn't to be tampered with merely to support a business
model, and that's all I see so far.

Joe