3Com 5500-EI Series, Reference Manual

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2-3
tracert
Syntax
tracert [ -a source-ip ] [ -f first-ttl ] [ -m max-ttl ] [ -p port ] [ -q num-packet ] [ -w timeout ] string
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Parameters
-a source-ip : Specifies the source interface IP address used by this command.
-f first-ttl : Specifies the initial TTL value of the packets to be sent, so as to only display the addresses of
those gateways on the path whose hop counts are not smaller than the hop count specified by the
first-ttl argument. For example, if the first-ttl argument is 3, the command displays the addresses of the
gateways from the third hop. The first-ttl argument ranges from 1 to 255 and defaults to 1.
-m max-ttl : Specifies the maximum TTL value of the packets to be sent. After the command sends a
packet with the maximum TTL, it will not send any more packets. With this argument, this command
only displays the addresses of those gateways from the source address to hop according to the hop
count specified by the argument. For example, if the max-ttl argument is 5, the command displays the
addresses of the gateways from the source to the fifth hop. The max-ttl argument ranges from 1 to 255
and defaults to 30.
-p port : Specifies the destination port of the packets to be sent. The port argument ranges from 0 to
65535 and defaults to 33434. Generally, you need not change the argument.
- q num-packet : Specifies the number of packets to be sent each time. The num-packet argument
ranges from 0 to 65,535 and defaults to 3.
-w timeout : Specifies the timeout time to wait for ICMP error packets. The timeout argument ranges
from 0 to 65,535 and defaults to 5,000 (in milliseconds).
string : Host name of the destination host, in the range of 1 to 20 characters.
Description
Use the tracert command to trace the gateways that the test packets pass through from the source
device to the destination device. This command is mainly used to check the network connectivity and
help locate the network faults.
The executing procedure of the tracert command is as follows: First, the source sends a packet with the
TTL of 1, and the first hop device returns an ICMP error message indicating that it cannot forward this
packet because of TTL timeout. Then, the source resends a packet with the TTL of 2, and the second
hop device also returns an ICMP TTL timeout message. This procedure goes on and on until a packet
gets to the destination or the maximum TTL is reached. During the procedure, the system records the
source address of each ICMP TTL timeout message in order to offer the path that the packets pass
through to the destination.
If you find that the network is faulty by using the ping command, you can use the tracert command to
find the faulty nodes in the network.
The tracert command can output the IP addresses of all the gateways that the packets pass through to
the destination. It outputs the string "***" if the response from a gateway times out.