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5.23.2 traceroute
The traceroute User EXEC command discovers the routes that packets will actually take when traveling
to their destination.
Syntax
traceroute ip-address |hostnme [size packet_size] [ttl max-ttl] [count packet_count] [timeout time_out]
[source ip-address] [tos tos]
ip-address — IP address of the destination host. An out-of-band IP address can be specified as
described in the usage guidelines. (Range: 1 - 160 characters)
hostname — Hostname of the destination host (Range: Valid IP Address)
size packet_size — Number of bytes in a packet. (Range: 40-1500)
ttl max-ttl—The largest TTL value that can be used. The traceroute command terminates when
the destination is reached or when this value is reached. (Range:1-255)
count packet_count — The number of probes to be sent at each TTL level. (Range:1-10)
timeout time_out — The number of seconds to wait for a response to a probe packet.
(Range:1-60)
source ip-address — One of the interface addresses of the device to use as a source address for
the probes. The device will normally pick what it feels is the best source address to use. (Range:
Valid IP Address)
tos tos — The Type-Of-Service byte in the IP Header of the packet. (Range: 0-255)
Default Configuration
size packet_size — The default is 40 bytes.
ttl max-ttl — The default is 30.
count packet_count — The default count is 3.
timeout time_out — The default is 3 seconds.
Command Mode
User EXEC mode
User Guidelines
The traceroute command works by taking advantage of the error messages generated by 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
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