DGS-6604 m traceroute
CLI Reference Guide
907
Default -w: 5 seconds
-i: 1
-m: 30
-p: 33434
-q: 3
-t: 0
-s: 40 bytes
Command Mode Management interface mode or User EXEC
Usage Guideline To interrupt traceroute after the command has been issued, press Ctrl-C.
The traceroute command uses the TTL field in the IP header to cause routers
and servers to generate specific return messages. traceroute starts by sending
a UDP datagram to the destination host with the TTL field set to 1. If a router
finds a TTL value of 1 or 0, it drops the datagram and sends back an ICMP time-
exceeded message to the sender. The traceroute facility determines the
address of the first hop by examining the source address field of the ICMP time-
exceeded message.
To identify the next hop, traceroute again sends a UDP packet but this time with
a TTL value of 2. The first router decrements the TTL field by 1 and sends the
datagram to the next router. The second router sees a TTL value of 1, discards
the datagram, and returns the time-exceeded message to the source. This
process continues until the TTL is incrementally increased to a value large
enough for the datagram to reach the destination host (or until the maximum TTL
is reached).
To determine when a datagram has reached its destination, traceroute sets the
UDP destination port in the datagram to a very large value that the destination
host is unlikely to be using. When a host receives a datagram with an
unrecognized port number, it sends an ICMP port unreachable error to the
source. This message indicates to the traceroute facility that it has reached the
destination.
Use the TOS option to see if different types of service cause routes to change.
Note : The specified OPTIONS can be any combination of each parameters.
However, the parameters must be specified in the alphabetical order and upper
case options are ahead of lower case options (similar to the PING command).
Examples This example shows how to traceroute the host with IP address
"172.50.71.123".
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