3Com 3CRUS2475 Command Reference Manual page 422

422 C 30: S M C
HAPTER YSTEM ANAGEMENT OMMANDS
User Guidelines
The traceroute command takesadvantage of the error messages
generated by the devices 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 device 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 device 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.