Ping

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See also: LAN | Ethernet

  1. In vernacular, the response time from computer to computer (correctly called Round Trip Time, or in short RTT)
  2. A network tool to test response time.

1. The response time from computer to computer

A measure of the round trip time between two computers, usually measured in miliseconds (ms). The smaller the number, the better. This a a measure of latency but one cannot extrapolate available bandwidth from such a measure. There are very high bandwidth but high letency links, like satellite links. While a network can transmit data at high speed, it may not have a quick response from machine to machine. This can be repaired by using switches instead of Hubs or by replacing outdated routers/hubs/switches between systems or as users on the same network increase. Increased network traffic can also affect ping time.

Ping times affect online gaming profoundly and often define LAN Parties. They also test the scalability of a network. As ping time begins to increase, the ability to add more users can create an inefficient network and even web browsing will seem to slow significantly.

When looking to an Internet company, it is good to run a ping command from your ISP to "www.yahoo.com", a very redundant and reliable server, to determine the quality and sometimes scalability of their equipment. A reasonably good connection should have lower than 100 milliseconds ping, usually listed as "time=100ms". Below 30ms is considered excellent. 400 ms is unacceptable except in rural areas.

2. A network tool to test response time.

Ping is a textmode tool available on almost any network-aware operating system. It is available by default on Windows via the Command/DOS prompt and UNIX systems. Usage is the same on both systems. At the prompt type:

ping www.yahoo.com

When connected to the network, you should see something similar to the following (taken from a Linux ping output):

64 bytes from 26.119.118.71: icmp_seq=0 ttl=51 time=42.6 ms
64 bytes from 26.119.118.71: icmp_seq=1 ttl=51 time=42.6 ms
64 bytes from 26.119.118.71: icmp_seq=2 ttl=51 time=42.8 ms
64 bytes from 26.119.118.71: icmp_seq=3 ttl=51 time=42.5 ms

Hit CTRL+C to end the process. The response time here averages 42.6 ms, a good response time.

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