The command ping is an easy and poetic tool for testing
network connectivity. It sends regular messages or packets to
the named remote machine, counts the time till each packet returns
home, and takes note if any packets get lost. Generally ping
continues to send packets until it is stopped by you with a ^c or delete command. Under SunOS, ping simply returns a
statement that the remote host is alive or that there is no
answer. However, using the -s option on Suns will make its
ping behave as we demonstrate here:
% ping arnor Or try /etc/ping, /usr/etc/ping, if ping not in path. PING arnor.thomas.hal.com: (127.29.140.13): 56 data bytes 64 bytes from 127.29.140.13: icmp_seq=0. time=3. ms 64 bytes from 127.29.140.13: icmp_seq=1. time=2. ms 64 bytes from 127.29.140.13: icmp_seq=2. time=3. ms [ctrl]-c User interrupts the program. -arnor.thomas.hal.com PING Statistics- 3 packets transmitted, 3 packets received, 0% packet loss. round-trip (ms) min/avg/max = 2/3/3
A 1% packet loss is not uncommon or a special matter for concern if the remote machine is not ``local.'' In fact, packet losses greater than 15% are not uncommon on wide area networks, such as those across countries or oceans. On local networks, though, there should be no more than an occasional packet lost. At present, local ethernets attain round trip times which are less than 5 milliseconds, and wide area networks have round trip times as long as hundreds of milliseconds.