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<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
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<p class=MsoNormal><b><font size=2 face=Tahoma><span style='font-size:10.0pt;
font-family:Tahoma;font-weight:bold'>From:</span></font></b><font size=2
face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'> Starlink
[mailto:starlink-bounces@lists.bufferbloat.net] <b><span style='font-weight:
bold'>On Behalf Of </span></b>David P. Reed<br>
<b><span style='font-weight:bold'>Sent:</span></b> Friday, July 9, 2021 11:40
AM<br>
<b><span style='font-weight:bold'>To:</span></b> starlink@lists.bufferbloat.net<br>
<b><span style='font-weight:bold'>Subject:</span></b> [Starlink] Starlink and
bufferbloat status?</span></font><o:p></o:p></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
<p style='margin:0in;margin-bottom:.0001pt'><font size=2 face=Arial><span
style='font-size:10.0pt;font-family:Arial'>Early measurements of performance of
Starlink have shown significant bufferbloat, as Dave Taht has shown.<o:p></o:p></span></font></p>
<p style='margin:0in;margin-bottom:.0001pt;overflow-wrap: break-word'><font
size=2 face=Arial><span style='font-size:10.0pt;font-family:Arial'> <o:p></o:p></span></font></p>
<p style='margin:0in;margin-bottom:.0001pt;overflow-wrap: break-word'><font
size=2 face=Arial><span style='font-size:10.0pt;font-family:Arial'>But...
Starlink is a moving target. The bufferbloat isn't a hardware issue, it should
be completely manageable, starting by simple firmware changes inside the
Starlink system itself. For example, implementing fq_codel so that bottleneck
links just drop packets according to the Best Practices RFC,<o:p></o:p></span></font></p>
<p style='margin:0in;margin-bottom:.0001pt;overflow-wrap: break-word'><font
size=2 face=Arial><span style='font-size:10.0pt;font-family:Arial'> <o:p></o:p></span></font></p>
<p style='margin:0in;margin-bottom:.0001pt;overflow-wrap: break-word'><font
size=2 face=Arial><span style='font-size:10.0pt;font-family:Arial'>So I'm
hoping this has improved since Dave's measurements. How much has it improved?
What's the current maximum packet latency under full load, Ive heard
anecdotally that a friend of a friend gets 84 msec. *ping times under full
load*, but he wasn't using flent or some other measurement tool of good quality
that gives a true number.<o:p></o:p></span></font></p>
<p style='margin:0in;margin-bottom:.0001pt;overflow-wrap: break-word'><font
size=2 face=Arial><span style='font-size:10.0pt;font-family:Arial'> <o:p></o:p></span></font></p>
<p style='margin:0in;margin-bottom:.0001pt;overflow-wrap: break-word'><font
size=2 face=Arial><span style='font-size:10.0pt;font-family:Arial'>84 msec is
not great - it's marginal for Zoom quality experience (you want latencies
significantly less than 100 msec. as a rule of thumb for teleconferencing
quality). But it is better than Dave's measurements showed.<o:p></o:p></span></font></p>
<p style='margin:0in;margin-bottom:.0001pt;overflow-wrap: break-word'><font
size=2 face=Arial><span style='font-size:10.0pt;font-family:Arial'> <o:p></o:p></span></font></p>
<p style='margin:0in;margin-bottom:.0001pt;overflow-wrap: break-word'><font
size=2 face=Arial><span style='font-size:10.0pt;font-family:Arial'>Now Musk
bragged that his network was "low latency" unlike other high speed
services, which means low end-to-end latency. That got him permission
from the FCC to operate Starlink at all. His number was, I think, < 5 msec.
84 is a lot more than 5<span style='background:yellow'>. (I didn't believe 5,
because he probably meant just the time from the ground station to the terminal
through the satellite.</span> <font color=navy><span style='color:navy'><o:p></o:p></span></font></span></font></p>
<p style='margin:0in;margin-bottom:.0001pt'><b><i><font size=2 color=navy
face=Arial><span style='font-size:10.0pt;font-family:Arial;color:navy;
font-weight:bold;font-style:italic'>[RR] So you are saying Musk might have used
“artistic license” to get a license out of the FCC??/ Shocking! Never heard
that before! I thought everyone simply told the FCC the truth and got licenses
based on technical merit, not marketing BS! Well, as the old saying goes: “If
you can’t dazzle them with your brilliance, baffle them with your bullshit!”<o:p></o:p></span></font></i></b></p>
<p style='margin:0in;margin-bottom:.0001pt'><b><i><font size=2 color=navy
face=Arial><span style='font-size:10.0pt;font-family:Arial;color:navy;
font-weight:bold;font-style:italic'><o:p> </o:p></span></font></i></b></p>
<p style='margin:0in;margin-bottom:.0001pt'><b><i><font size=2 color=navy
face=Arial><span style='font-size:10.0pt;font-family:Arial;color:navy;
font-weight:bold;font-style:italic'>:^))))<o:p></o:p></span></font></i></b></p>
<p style='margin:0in;margin-bottom:.0001pt'><b><i><font size=2 color=navy
face=Arial><span style='font-size:10.0pt;font-family:Arial;color:navy;
font-weight:bold;font-style:italic'><o:p> </o:p></span></font></i></b></p>
<p style='margin:0in;margin-bottom:.0001pt'><font size=2 face=Arial><span
style='font-size:10.0pt;font-family:Arial'>But I regularly get 17 msec. between
<st1:State w:st="on">California</st1:State> and <st1:place w:st="on"><st1:State
w:st="on">Massachusetts</st1:State></st1:place> over the public Internet)<o:p></o:p></span></font></p>
<p style='margin:0in;margin-bottom:.0001pt;overflow-wrap: break-word'><font
size=2 face=Arial><span style='font-size:10.0pt;font-family:Arial'> <o:p></o:p></span></font></p>
<p style='margin:0in;margin-bottom:.0001pt;overflow-wrap: break-word'><font
size=2 face=Arial><span style='font-size:10.0pt;font-family:Arial'>So 84 might
be the current status. That would mean that someone at Srarlink might be paying
some attention, but it is a long way from what Musk implied.<o:p></o:p></span></font></p>
<p style='margin:0in;margin-bottom:.0001pt;overflow-wrap: break-word'><font
size=2 face=Arial><span style='font-size:10.0pt;font-family:Arial'> <o:p></o:p></span></font></p>
<p style='margin:0in;margin-bottom:.0001pt;overflow-wrap: break-word'><font
size=2 face=Arial><span style='font-size:10.0pt;font-family:Arial'> <o:p></o:p></span></font></p>
<p style='margin:0in;margin-bottom:.0001pt;overflow-wrap: break-word'><font
size=2 face=Arial><span style='font-size:10.0pt;font-family:Arial'>PS: I forget
the number of the RFC, but the number of packets queued on an egress link
should be chosen by taking the hardware bottleneck throughput of any path,
combined with an end-to-end Internet underlying delay of about 10 msec. to
account for hops between source and destination. Lets say Starlink allocates 50
Mb/sec to each customer, packets are limited to 10,000 bits (1500 * 8), so the
outbound queues should be limited to about 0.01 * 50,000,000 / 10,000, which
comes out to about 250 packets from each terminal of buffering, total, in the
path from terminal to public Internet, assuming the connection to the public
Internet is not a problem.<o:p></o:p></span></font></p>
<p style='margin:0in;margin-bottom:.0001pt;overflow-wrap: break-word'><font
size=2 face=Arial><span style='font-size:10.0pt;font-family:Arial'> <o:p></o:p></span></font></p>
<p style='margin:0in;margin-bottom:.0001pt;overflow-wrap: break-word'><font
size=2 face=Arial><span style='font-size:10.0pt;font-family:Arial'> <o:p></o:p></span></font></p>
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