418 System Management
•
ip-address —
One of the device’s interface addresses to use as a source address for the probes. The
device normally selects what it feels is the best source address to use.
•
tos —
The
Type-Of-Service byte in the IP Header of the packet. (Range: 0 - 255)
Default Configuration
• The default number of bytes in a packet is 40.
• The default maximum TTL value is 30.
• The default number of probes to be sent at each TTL level is 3.
• The default timeout interval in seconds is 3.
Command Mode
User EXEC mode.
User Guidelines
• The
traceroute
command takes advantage of the error messages generated by the routers when a
datagram exceeds its time-to-live (TTL) value.
• The
traceroute
command starts by sending probe datagrams with a TTL value of one. This causes the
first router to discard the probe datagram and send back an error message. The
traceroute
command
sends several probes at each TTL level and displays the round-trip time for each.
• The
traceroute
command sends out one probe at a time. Each outgoing packet may result in one or
two error messages. A "time exceeded" error message indicates that an intermediate router has seen
and discarded the probe. A "destination unreachable" error message indicates that the destination
node has received the probe and discarded it because it could not deliver the packet. If the timer goes
off before a response comes in, the
traceroute
command prints an asterisk (*).
• The
traceroute
command terminates when the destination responds, when the maximum TTL is
exceeded or when the user interrupts the trace by pressing
Esc
.
book.book Page 418 Thursday, December 18, 2008 7:40 PM
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