Understanding the network.pdf - Back to Home

Ping implementations vary from platform to platform in terms of their command line
interface (CLI), supported features, and protocols. When using ping on a system for
the first time, check the documentation to see what options are available. On a UNIX
system, this can be done using the command. On Cisco IOS, use
, and on Windows systems, type C:\ ping and the CLI usage and
options are displayed.
Using Ping
The ping command can executed from the command line in both the Windows NT
and UNIX environments, using the following command syntax . Depending on the ping implementation, either a group or stream of ICMP
messages will be sent to the specified target host. When debugging user network
problems, this should be the first thing you ask them to do. If the ping test is
successful, move on to the problem specifics. Quite often, a user will complain that
he cannot get email, when it turns out that he cannot reach anything on the network
because he is not physically connected or the IP address information is not properly
configured.
When using the ping command the host's IP implementation needs to be functioning
correctly. This can easily be accomplished by pinging the loopback interface that
uses the IP address 127.0.0.1:
%ping 127.0.0.1
PING 127.0.0.1 (127.0.0.1): 56 data bytes
64 bytes from 127.0.0.1: icmp_seq=0 ttl=255 time=0.478 ms
64 bytes from 127.0.0.1: icmp_seq=1 ttl=255 time=0.161 ms
^C
—- 127.0.0.1 ping statistics —-
2 packets transmitted, 2 packets received, 0% packet loss
round-trip min/avg/max = 0.161/0.319/0.478 ms
%
If this ping test fails, the host's IP implementation is not functioning correctly or not
configured (an all too common problem with hosts configured using DHCP).
Check the host's IP configuration information. On a UNIX host, this is done using the
command, which will list all of the configured interfaces and if they
are up or down. On a Cisco router, you can use the