Name
trace — command
Synopsis
trace [host
]
Description
This command allows you to determine the most likely path to a
specified host
. It is often useful in
troubleshooting, and is similar to the traceroute
command on Unix systems or the tracert
command on
Windows systems. If you omit the hostname, you’ll be prompted
for the necessary information. As with the ping
command, the prompts differ depending on the mode you are in. The
output from the trace
command uses the special
characters shown in Table 15-22.
Table 17-9. Special characters for trace output
Character |
Meaning |
---|---|
xx msec |
Round-trip time in milliseconds |
* |
Packet timeout |
? |
Unknown packet received |
A |
Administratively unreachable; possibly means that an access list or equivalent function on another router is blocking the packets |
H |
Host is unreachable |
N |
Network is unreachable |
P |
Protocol is unreachable |
Q |
Source quench |
U |
Port unreachable |
Example
This example shows what happens when you use the
trace
command without supplying a hostname. Note
that you’re prompted for many values that can’t be
specified on the command line. Omitting the hostname therefore gives
you more control over the command’s behavior than you would
otherwise have.
Router#trace Protocol [ip]: Protocol Target IP address: 10.10.1.2 Can be hostname or network address Source address: The IP address of the interface to use Numeric display [n]: y Numeric display is not the default Timeout in seconds [3]: Seconds to wait for each probe Probe count [3]: ...
Get CISCO IOS in a Nutshell now with the O’Reilly learning platform.
O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.