Ankit Singla
University of Illinois
Brighten Godfrey
University of Illinois
Bala Chandrasekaran
Duke University
“How long until our pigeon system rivals those of
the continental powers?”
– The Nineteenth Century (British Periodical), 1899
[telegeography.com]
A toy experiment
$ wget theoatmeal.com
• 430ms (fetch size 20KB)
$ ping 208.70.160.53
• 55ms
Champaign-Portland roundtrip distance
• 5700 kilometers
• 19ms at the speed of light in vacuum
23x inflation over c-latency!
Time to fetch Alexa top 500 HTML
CDF
Inflation over c-latency
Time to fetch Alexa top 500 HTML
CDF
34x
Inflation over c-latency
0.1s ~ 1% revenue
A speed-of-light Internet would enable
“tele-interaction”
Remote collaboration and games
Tele-surgery with haptic feedback
The new and unexpected
10
Hit it!!
A speed-of-light Internet would provide
“Instant” Access
A screen change occurring within 30ms of
clicking a button appears instantaneous.
12
30ms
[Wikipedia user Toffelginkgo]
latency
radius
Community size
A speed of light Internet would provide
super-linear growth in community size
c
2
c
20
49x
Latency radius
15
Benefit
Population reachable (in
billions)
Latency and community size
Super-linear growth
Communication
speed
Research
progress
Why are we so
far from the
speed of light?
[comcast.com]
[verizon.com]
[speedtest.net]
Latency inflation breakdown
CDF
Inflation over c-latency to the Web server
Latency inflation breakdown
DNS
CDF
5.4x
Inflation over c-latency to the Web server
Latency inflation breakdown
Router-path
DNS
CDF
2.3x
Inflation over c-latency to the Web server
1
2
3
4
Latency inflation breakdown
Router-path
Min ping
DNS
CDF
3.2x
Inflation over c-latency to the Web server
Router path vs. ping
Inflation in fiber distances
Ground truth data on fiber lengths!
Inflation in fiber distances
CDF
Inflation over geo-distance
Inflation in fiber distances
Road
CDF
Inflation over geo-distance
Inflation in fiber distances
Road
Fiber
CDF
Inflation over geo-distance
Inflation in fiber distances
Road
Road
Fiber
GÉANT
CDF
CDF
Fiber
Internet 2
Inflation over geo-distance
Road
Fiber
Inflation over geo-distance
CDF
ESnet*
Inflation over geo-distance
* Dhruv Diddi (UIUC) helped process ESnet data
Latency inflation breakdown
Router-path
Min ping
TCP handshake
DNS
CDF
3.2x
Inflation over c-latency to the Web server
Latency inflation breakdown
Router-path
Min ping
TCP handshake
DNS
TCP transfer
CDF
8.7x
Inflation over c-latency to the Web server
Latency inflation breakdown
Router-path
Min ping
TCP handshake
DNS
TCP transfer
Total time
CDF
24.6x
Inflation over c-latency
Latency inflation breakdown
Total time
(24.6x)
=
DNS resolution (5.4x)
+
TCP handshake (3.2x)
+
TCP transfer (8.7x)
Latency inflation breakdown
Total time
(24.6x)
=
DNS resolution (5.4x)
+
TCP handshake (3.2x)
+
Request (3.2x)
+
TCP transfer (8.7x)
Inflation at lower layers affects
everything!
Absent inflation in the lower layers …
Total time
(24.6x)
8.2x
=
1.7x
DNS resolution (5.4x)
+
1x
TCP handshake (3.2x)
+
1x
Request (3.2x)
+
2.7x
TCP transfer (8.7x)
(Normalized by the 3.2x inflation in minimum ping
time)
Could we build
a speed-of-light
Internet?
[wired.com]
•
•
•
•
•
2526 towers from FCC database connecting 300 city pairs
Median stretch 1.08, 90th percentile stretch 1.15
400Mbps links, 70km maximum range
Enough capacity to carry 1% of non-video traffic in U.S.
Approximate cost: $250M up front, plus $100M per year
Interfacing with the Internet
Within the network,
• Ubiquitous DNS replication
• Eliminate TCP three-way handshake
• Speed up TCP slow-start with larger initial window
Across the network,
• Employ “cold potato” routing – route each packet as
close to its destination as possible
At the edge of the network,
• Proxies terminate connections originating in the network
Future work…