Technical data

Troubleshooting Techniques and Tools
1.2 Isolating Problems
• A definition for localhost is missing from the local database.
If the ping command for localhost does not respond correctly, try the ping
command with the IP address 127.0.0.1 . If this command displays correct
output, the TCPIP database is missing a definition for localhost .
If localhost returns the data correctly at this point, use the ping command to
test another host on the same local network. If you are able to reach this host,
then test remote hosts farther and farther away from the local host.
If the remote host does not respond to the request, the
ping command displays
the following message:
TCPIP> ping a7u1kt
ping: unknown host a7u1kt
%SYSTEM-F-UNREACHABLE, remote node is not currently reachable
If you used an IP address in the ping command, the output may be:
TCPIP> ping 10.10.22.1
PING 10.10.22.1 (10.10.22.1): 56 data bytes
----10.10.22.1 PING Statistics----
4 packets transmitted, 0 packets received, 100% packet loss
%SYSTEM-F-TIMEOUT, device timeout
These error messages could indicate that:
• There is no host with the specified host name.
• Using the host file or DNS/BIND, the system was not able to resolve the
specified host name to an IP address.
• There is no host with that IP address.
• The host is down and not responding.
The following sample shows the
ping statistics displayed:
TCPIP> ping chester
PING chester (16.20.208.53): 56 data bytes
64 bytes from 16.20.208.53: icmp_seq=0 ttl=64 time=0 ms
64 bytes from 16.20.208.53: icmp_seq=1 ttl=64 time=1 ms
64 bytes from 16.20.208.53: icmp_seq=2 ttl=64 time=0 ms
64 bytes from 16.20.208.53: icmp_seq=3 ttl=64 time=1 ms
----chester PING Statistics----
4 packets transmitted, 4 packets received, 0% packet loss
round-trip (ms) min/avg/max = 0/0/1 ms
The ping command displays statistics on packets sent; packets received; the
percentage of packets lost; and the minimum, average, and maximum round-trip
packet times.
If you do not specify command options, the
ping command displays the results
of each ICMP request in sequence, the number of bytes received from the remote
host, and the round-trip time on a per-request basis.
Use the output from the ping command to help determine the cause of direct and
indirect routing problems such as host is unreachable, connection timed out, and
network is unreachable.
1–4 Troubleshooting Techniques and Tools