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Re: [Spud] [tsvwg] One bit for latency bandwidth tradeoff

Michael Welzl <michawe@ifi.uio.no> Tue, 26 January 2016 09:59 UTC

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From: Michael Welzl <michawe@ifi.uio.no>
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Cc: Youjianjie <youjianjie@huawei.com>, "tsvwg@ietf.org" <tsvwg@ietf.org>, "spud@ietf.org" <spud@ietf.org>
Subject: Re: [Spud] [tsvwg] One bit for latency bandwidth tradeoff
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> On 26 Jan 2016, at 10:54, Brian Trammell <ietf@trammell.ch> wrote:
> 
> hi Jianjie,
> 
> Our thinking on this in the context of the prototype is either (a) that the latency tradeoff be bound to a tube (which would require (1) more than one bit to encode the tradeoff and (2) that the forwarding/queueing decision also always do a lookup on the tube ID, which is not optimal), or (b) that one of the reserved bits in cmd/flags be used for this.
> 
> It does not appear that the current definitions of the DSCP codepoints would allow compatible reuse of either a single bit or any of the codepoints as a signal for this tradeoff. One could perhaps go to the effort to allocate a new set of codepoints in Pool 3, say 0bx11101, for "DSCP Loss/Latency Tradeoff" -- I'd want to get the opinion of someone with some DSCP expertise to say how difficult this would be.

+1 - this is exactly Jianjie and I are asking about...  how difficult it would be, and if folks would consider this reasonable

Cheers,
Michael

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