% ping -s cs.swarthmore.edu PING cs.swarthmore.edu: 56 data bytes 64 bytes from 130.58.68.1: icmp_seq=0 ttl=251 time=66 ms 64 bytes from 130.58.68.1: icmp_seq=1 ttl=251 time=45 ms 64 bytes from 130.58.68.1: icmp_seq=2 ttl=251 time=46 ms ^C —- cs.swarthmore.edu ping statistics —- 3 packets transmitted, 3 packets received, 0% packet loss round-trip min/avg/max = 45/52/66 ms
This case tells us that for cs.swarthmore.edu it takes about 46 milliseconds for a packet to go from Widener to Swarthmore College and back again. It also gives the average and worst-case speeds, and any packet loss that may have occurred (e.g. because of network congestion).
While ping generally doesn't hurt network performance, you shouldn't use it too often—-usually once or twice will leave you relatively sure of the other system's state.
Talk
Sometimes email is clumsy and difficult to manage when one really needs to have an interactive conversation. The Internet provides for that as well, in the form of talk. Two users can literally see each other type across thousands of miles.
To talk with Bart Simpson at Widener, one would type
talk bart@@cs.widener.edu
which would cause a message similar to the following to be displayed on Bart's terminal:
Message from Talk_Daemon@cs.widener.edu at 21:45 … talk: connection requested by joe@ee.someplace.edu talk: respond with: talk joe@ee.someplace.edu
Bart would, presumably, respond by typing talk joe@ee.someplace.edu. They could then chat about whatever they wished, with instantaneous response time, rather than the write-and-wait style of email. To leave talk, on many systems one would type Ctrl-C (hold down the Control key and press C). Check local documentation to be sure.