- August
- 16th
- 2008
Global Positioning from PING response time
Posted by MaEl in: Bits-and-Bytes Comments
PING probably the most popular tool to determine network response time.
How PING works??
The PING program works much like a sonar echo-location, sending a small packet of information containing an ICMP ECHO_REQUEST to a specified computer, which then sends an ECHO_REPLY packet in return.Ping shows the time for a roundtrip, i.e. 2 x the distance.
Some PING test on piXca.net
location avg.(ms) |
location avg.(ms) |
Santa Clara, U.S.A. 132.7 Florida, U.S.A. 197.5 Vancouver, Canada 119.0 Austin1, U.S.A. 171.9 New York, U.S.A. 202.2 Austin, U.S.A. 171.5 San Francisco, U.S.A. 120.5 Hong Kong, China 62.6 Sydney, Australia 135.7 Amsterdam3, Netherlands 239.0 Chicago, U.S.A. 155.6 Amsterdam2, Netherlands 240.8 Stockholm, Sweden 294.0 London, United Kingdom 241.4 Munchen, Germany 217.0 |
Singapore, Singapore 97.2 Cologne, Germany 279.0 Paris, France 243.7 Amsterdam, Netherlands 240.4 Melbourne, Australia 170.5 Krakow, Poland 297.4 Cagliari, Italy 259.4 Madrid, Spain 301.5 Copenhagen, Denmark 287.5 Lille, France 249.6 Zurich, Switzerland 281.7 Porto Alegre, Brazil 336.4 Johannesburg, South Africa 482.1 Shanghai, China 377.0 |
(PING done by http://www.just-ping.com/)
Nearest City –> Hong Kong (approx 30ms).
Most far City –> Johannesburg (approx 241ms).
Let say my server located somewhere in Tokyo.
The distance between Tokyo - Hong Kong is 3000km.
Given that almost cities connected by under sea fiber cable so, the network
speed is theoretically limited by the speed of light. (approx 3×10^8 m/s).
Some speed calculations:
Hong Kong : 3000 km / 30 ms = 1.00×10^8 m/s
Singapore : 5500 km / 47 ms = 1.17×10^8 m/s
Vancouver : 7700 km / 60 ms = 1.28×10^8 m/s
the results is 1/3 of light speed..
so slow.. why??
# The actual distance traveled will be longer, more like zig zag than a straight line.
# Repeaters, switches and routers will slow down transfer speeds. The more equipment the signal has to pass through (for example routers), the longer it will take to reach its target.
# The actual speed of the signal will never quite match the speed of light. Even with fiber optics (glass) the speed of light is about 30% slower than through vacuum or air, and most of the distance covered will be through fiber.
# A beam of light bounces around like a pinball when it travels along the thin (admittedly extremely thin) fiber, and that will of course make the distance traveled even longer.
World map of submarine cable systems
No wonder Johannesburg is super slow
Reference:
Theoretical vs real-world speed limit of Ping
Ping Command
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