Hi Colin,
> On 16. Mar 2024, at 20:26, Colin_Higbie <chigb...@higbie.name> wrote: > > Sebastian, > > Not sure if we're saying the same thing here or not. While I would agree with > the statement that all else being equal, lower latency is always better than > higher latency, there are definitely latency (and bandwidth) requirements, > where if the latency is higher (or the bandwidth lower) than those > requirements, the application becomes non-viable. That's what I mean when I > say it falls short of being "good enough." > > For example, you cannot have a pleasant phone call with someone if latency > exceeds 1s. Yes, the call may go through, but it's a miserable UX. [SM] That is my point, miserable but still funktional, while running a 100Kbps constant bitrate VoIP stream over a 50 Kbps link where the loss will make thinks completely imperceivable... > For VoIP, I would suggest the latency ceiling, even under load, is 100ms. > That's a bit arbitrary and I'd accept any number roughly in that ballpark. If > a provider's latency gets worse than that for more than a few percent of > packets, then that provider should not be able to claim that their Internet > supports VoIP. [SM] Interestingly the ITU claims that one way mouth-to-ear delay up to 200ms (aka 400ms RTT) results in very satisfied and up to 300ms OWD in satisfied telephony customers (ITU-T Rec. G.114 (05/2003)). That is considerably above your 100ms RTT. Now, I am still trying to find the actual psychophysics studies the ITU used to come to that conclusion (as I do not believe the numbers are showing what they are claimed to show), but policy makers still look at these numbers an take them as valid references. > If the goal is to ensure that Internet providers, including Starlink, are > going to provide Internet to meet the needs of users, it is essential to > understand the good-enough levels for the expected use cases of those users. > > And we can do that based on the most common end-user applications: > > Web browsing > VoIP > Video Conferencing > HD Streaming > 4K HDR Streaming > Typical Gaming > Competitive Gaming > And maybe throw in to help users: time to DL and UL a 1GB file [SM] Only if we think of latency as a budget, if I can competitively play with a latency up to 100ms, any millisecond of delay I am spending on the access link is not going to restrict my "cone" of players I can match radius with by approximately 100Km... > Similarly, if we're going to evaluate the merits of government policy for > defining latency and bandwidth requirements to qualify for earning taxpayer > support, that comes down essentially to understanding those good-enough > levels. [SM] Here is the rub, for 100 Kbps VoIP it is pretty simple to understand that it needs capacity >= 100 Kbps, but if competitive gaming needs an RTT <= 100 ms, what is an ecceptable split between access link and distance? > > Cheers, > Colin > > -----Original Message----- > From: Sebastian Moeller <moell...@gmx.de> > Sent: Saturday, March 16, 2024 3:10 PM > To: Colin_Higbie <chigb...@higbie.name> > Cc: David Lang <da...@lang.hm>; Dave Taht via Starlink > <starlink@lists.bufferbloat.net> > Subject: Re: [Starlink] Itʼs the Latency, FCC > >> ... > > Well, for most applications there is an absolute lower capacity limit below > which it does not work, and for most there is also an upper limit beyond > which any additional capacity will not result in noticeable improvements. > Latency tends to work differently, instead of a hard cliff there tends to be > a slow increasing degradation... > And latency over the internet is never guaranteed, just as network paths > outside a single AS rarely are guaranteed... > Now for different applications there are different amounts of delay that > users find acceptable, for reaction time gates games this will be lower, for > correspondence chess with one move per day this will be higher. Conceptually > this can be thought of as a latency budget that one can spend on different > components (access latency, transport latency, latency variation buffers...), > and and latency in the immediate access network will eat into this budget > irrevocably ... and that e.g. restricts the "conus" of the world that can be > reached/communicated within the latency budget. But due to the lack of a hard > cliff, it is always easy to argue that any latency number is good enough and > hard to claim that any random latency number is too large. > > Regards > Sebastian > > _______________________________________________ Starlink mailing list Starlink@lists.bufferbloat.net https://lists.bufferbloat.net/listinfo/starlink
