Re: [tsvwg] [Fwd: Re: Traffic protection as a hard requirement for NQB]

Jonathan Morton <chromatix99@gmail.com> Mon, 09 September 2019 20:29 UTC

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From: Jonathan Morton <chromatix99@gmail.com>
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Date: Mon, 9 Sep 2019 23:29:11 +0300
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To: Steven Blake <slblake@petri-meat.com>
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Subject: Re: [tsvwg] [Fwd: Re: Traffic protection as a hard requirement for NQB]
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> On 9 Sep, 2019, at 7:31 pm, Steven Blake <slblake@petri-meat.com> wrote:
> 
> How do you estimate how much NQB traffic there might be? How would you tune this? My assumption is that this whole scheme only survives if the amount of NQB traffic is always so small relative to any link's capacity (< 5%) that you just allocation a small fraction of link capacity to NQB and forget about it. In which case, WRR scheduling doesn't give you good latency because your HOL NQB packet might have to wait for >= 20 MTU/link rate to get serviced.

I think we are also dancing around a more general problem here.  If we are having to use straw-man implementations to argue about the merits of the PHB, that implies that we don't have a real implementation to experiment with.

I would advise the authors to come up with a real implementation that has the behaviour they want and adequate robustness, and then we can re-open the discussion with "running code" to work from.

 - Jonathan Morton