[tsvwg] A word for "does not have a significantly negative impact on traffic using standard congestion control"?

Bob Briscoe <ietf@bobbriscoe.net> Tue, 09 March 2021 01:19 UTC

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From: Bob Briscoe <ietf@bobbriscoe.net>
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Date: Tue, 09 Mar 2021 01:19:12 +0000
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Subject: [tsvwg] A word for "does not have a significantly negative impact on traffic using standard congestion control"?
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In the survey of the L4S Prague Requirements, we got quite significant 
push-back from developers about our two requirements to fall back to 
Reno-Friendly (which the draft defines as a translation of 
'TCP-Friendly' into transport-agnostic language, 'cos TCP isn't the only 
transport these days).

Basically, people don't want to have to fall back to something as lame a 
Reno (apologies if that's disparaging, but I'm just the messenger).

I was hoping people would interpret 'Reno-Friendly' liberally. But 
everyone takes Reno-Friendly to mean quite close to Reno behaviour - not 
surprising really, given the definition of TCP-Friendly in TFRC is 
roughly within 2x of Reno [RFC5348] (pasted at the end).

What I'm looking for is a word that means "does not have a significantly 
negative impact on traffic using standard congestion control", which
RFC5033 allows for experimental congestion controls.

==Details from the RFCs==

RFCRFC2914 (borrowing from RFC2309) defines TCP-compatible to mean the 
same behaviour as Reno (essentially).

RFC5348 defines the term TCP-Friendly, which was originally intended for 
real-time media - to allow the rate to temporarily stray from 
TCP-compatible because it needed to remain more stable as available 
capacity varied. But it was also used for regular elastic congestion 
controls like Cubic. Here's the TFRC definition.

    TFRC is designed to be reasonably fair when competing for bandwidth
    with TCP flows, where we call a flow "reasonably fair" if its sending
    rate is generally within a factor of two of the sending rate of a TCP
    flow under the same conditions.  However, TFRC has a much lower
    variation of throughput over time compared with TCP, which makes it
    more suitable for applications such as telephony or streaming media
    where a relatively smooth sending rate is of importance.

In RFC5033, Sally Floyd wrote this, which is a useful turn of phrase. 
I'd just like to find a shorter way of saying it:

        Alternate congestion controllers that have a
        significantly negative impact on traffic using standard
        congestion control may be suspect


Bob Briscoe                               http://bobbriscoe.net/