Unfortunately, for consumer broadband connections, uplink speeds
tend to be much lower than downlink
speeds: Comcast’s standard high-speed Internet package, for example,
offers 6Mbps for download but only
384Kbps for upload (1/16th of download throughput). 11
This limitation is not as acute today
as it was nearly a decade ago when upload speeds in the U.S. hovered around
.5Mbps. Figure 1 shows the current
upload and download as taken from
Speedtest.net (http://www.speedtest.
net/reports/). These data points show
that global “last-mile” throughput
rates are nearly 30 times their 2008
counterparts. Is this enough? Would a
peer with an upload rate at the lower
quartile of these metrics (~4Mbps)
suffice? This question has been thoroughly explored in regard to actual
webpage load time.
When Mike Belshe, of Google
SPDY fame, looked at the relationship
between end-client bandwidth and
page-load time, he discovered that
“bandwidth doesn’t matter (much).” 3
Once the client’s available bandwidth
reached 5Mbps, the impact on the end
user’s page load is negligible. Figure
2 shows page-load time as a function
of client bandwidth, assuming a fixed
RTT (round-trip time) of 60ms.
Availability. The next major hurdle
for the distributed Internet is peer
availability. Namely, are there enough
peers, and are they online and available
for enough time to provide value? In the
past 10 years the edge device count has
certainly increased, but has it increased
enough? Looking at “Internet Trends
2017,” 14 compiled by Mary Meeker of
the venture capital firm KPCB, you
can see how much the “available peer”
count has increased over the past ten
years from mobile alone (see Figure 3).
Today, approximately 49% of the
world’s population is connected10—
around 3. 7 billion people, many with
multiple devices—so that’s a big
pool of edge devices. Peter Levine of
the venture capital firm Andressen
Horowitz has taken us out a few years
further and predicted we will shortly
be going beyond billions and heading
toward trillions of devices. 12
You can get a sense of scale by looking at an Edgemesh network for a single e-commerce customer’s website
with a global client base.
It’s probably safe to say there are
enough devices online, but does the
average user stay online long enough
to be available? What is “long enough”
for a peer to be useful?
A sensible place to start might be to
want peers to be online long enough
for any peer to reach any other peer
anywhere on the globe. Given that, we
can set some bounds.
The circumference of the Earth is
approximately 40,000km. The rule of
thumb is that light takes 4. 9 microseconds to move 1km through fiber
optics. That would mean data could
circumnavigate the globe in about
1/5th of a second (196 milliseconds).
Oh, if wishing only made it so, but as
Stanford Unversity’s Stuart Cheshire
points out in “It’s the Latency, Stupid,” 6 the Internet operates at least a
factor of two slower than this. This 2x
slowdown would mean it would take
approximately 400 milliseconds to
get around the globe. Unfortunately,
I have spent some time in telecom—
specifically in latency-optimized businesses13 —and I think this time needs
to be doubled again to account for
global transit routing; thus, the data
can go around the world in some 800
milliseconds. If users are online and
available for sub-800 millisecond in-
Figure 1. Bandwidth rates (upload/download, broadband/mobile).
Terrestrial Yo Y% Mobile Yo Y%
Region
Download
(Mbps)
Upload
(Mbps) Download Upload
Download
(Mbps)
Upload
(Mbps) Download Upload
UnitedStates 54. 97 18. 88 42% 51% 19. 61 7. 94 794% 28%
UnitedKingdom 40. 12 40. 12 18% 23% 24. 19 10.03 38% 31%
Singapore 190.9 178.69 18% 20% 45. 61 17. 93 16% 13%
HongKong 153.53 146.69 13% 0% 18. 9 8. 78 5% 1%
Brazil 16. 53 6.08 8% 11% 11. 31 4. 27 37% 35%
Figure 2. Page load time as a function of client bandwidth.
1
3500
3000
2500
2000
1500
1000
500
0
2345678910
Pa
ge
L
oa
d T
ime(m
s)
Client Bandwidth (Mbps)
3106
1950
1632
1496 1443 1406 1388 1379 1368 1360