Ping
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Screengrab_-_ping_in_a_win2k_command_window.png
Ping is the name of a computer network tool used on TCP/IP networks (such as the Internet). It provides a basic test of whether a particular host is operating properly and is reachable on the network from the testing host. It works by sending ICMP packets to the target host and listening for replies; its operation is analogous to active sonar in submarines, in which an operator issues a pulse of energy (a network packet) at the target, which then bounces from the target and is then received by the operator, hence the name.
The author of the tool, Mike Muuss, named it after the pulses of sound made by a sonar. (Later Dave Mills provided a backronym, "Packet Internet Grouper (Groper)" [1] (http://ftp.arl.mil/~mike/ping.html))
The usefulness of ping in assisting the diagnosis of Internet connectivity issues was impaired from late in 2003, when a number of Internet Service Providers filtered out ICMP Type 8 (echo request) messages at their network boundaries. Internet worms such as Welchia flooded the Internet with ping requests as they sought to locate new hosts to infect, causing problems to routers across the Internet.
Related network tools include traceroute and, on Windows NT-based systems, pathping.
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Sample ping output
The output of ping, and its cousins, generally consists of the packet size used, the host queried, the ICMP sequence number, the time to live, and the latency, with all times given in milliseconds, and times below 10 milliseconds often having low accuracy.
Below is a sample output where we ping the wikipedia.com server:
$ ping -c 5 wikipedia.com PING wikipedia.com (130.94.122.195): 56 data bytes 64 bytes from 130.94.122.195: icmp_seq=0 ttl=235 time=284.3 ms 64 bytes from 130.94.122.195: icmp_seq=1 ttl=235 time=292.9 ms 64 bytes from 130.94.122.195: icmp_seq=2 ttl=235 time=289.7 ms 64 bytes from 130.94.122.195: icmp_seq=3 ttl=235 time=282.4 ms 64 bytes from 130.94.122.195: icmp_seq=4 ttl=235 time=272.0 ms --- wikipedia.com ping statistics --- 5 packets transmitted, 5 packets received, 0% packet loss round-trip min/avg/max = 272.0/284.2/292.9 ms
Interpretation of ping times
To have some comparison for internet ping times, consider that the shortest possible ping to the other side of our planet is 85 ms. That is because 85 ms is the time the light needs to travel to the other side and back in a straight line through the earth. No signal can travel faster than light. The shortest possible ping would be 133 ms if we avoided a subterranean route. In practice, the actual ping is always higher, 333 ms not being unusual.
Slang usage
Players of multiplayer online video games often use the term "ping" to refer to the network latency seen between their computer and the game server (or another player). This could be reported as an averaged time in milliseconds, or more generally as "low ping" or "high ping". This usage is common with players of a variety of FPS and RTS games. In most cases, being a so-called "low ping bastard" is desirable because lower latency provides smoother gameplay by allowing more frequent updates of game data. In some cases, though, games seem to give unfair advantage to high-ping users, as in some iterations of the Half-Life engine.
In this sense, ping is conflated with lag – one may "lag out" due to high ping.
The method used by the game programmers to determine ping times will often not use the traditional ICMP echo request and reply packets, but instead piggyback the functionality onto existing game data packets (often using UDP).
Slang usage (2)
Slang term used in business referring to the practice of (usually) informally contacting multiple people in an organization to ferret differences in opinion with the intent to locate an attractive opinion (to the seeker) which may be misrepresented as fact. Example: "Joe pinged Bill and Tom trying to get a better price.". Another form of usage is to describe an attempt to get a reply from someone. Example: "I'll ping you again tomorrow if I don't hear from you tonight."
Slang usage (3)
Ping also refers to an ability in the trading card game Magic the Gathering. An example is the card Progidal Sorcerer, which taps to deal 1 damage. The slang way of saying that is "I ping you for one from Tim(The nickname of the Sorcerer)".
External links
- The Story of the PING Program (http://ftp.arl.mil/~mike/ping.html) by its author, Mike Muuss
- Ping Utility (http://www.webmaster-toolkit.com/ping.shtml)
- Unix man pages: ping (8) (http://www.rt.com/man/ping.8.html)
- Free Web-based Ping Utility (http://www.internetipaddress.com/ping.aspx)de:Ping (Datenübertragung)