Why is there three time values in the tracert command output?

Created: Sep 17, 2019 06:20:39Latest reply: Sep 17, 2019 07:03:32 110 3 0 0
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I have had a question for a long time. Why is there three time values in the tracert command output?


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Popeye_Wang
Admin Created Sep 17, 2019 06:25:02 Helpful(0) Helpful(0)

Hi Sprout,
Thisis related to the tracert process. By default, the source port sends three UDPpackets in a trace test. If you run the tracert command on a Huawei device, you can use the parameter -q  to specify the number of sent packets.
For example:


<HUAWEI> tracert -q 5 10.10.0.10


traceroute to 10.10.0.10 (10.10.0.10), hops max: 18, packetlength: 40,press CTRL_C to break


1 10.3.112.1 (10.3.112.1) 17 ms 17 ms 27 ms 17ms 20ms


2 10.32.216.1 (10.32.216.1) 19 ms 19 ms 19 ms 19ms 18ms


3 10.32.168.22 (10.32.168.22) 20 ms 39 ms 39 ms 27ms 30ms


4 * * * * *


5 * * * * *


6 10.10.0.10 (10.10.0.10) 339 ms 279 ms 279 ms 600ms 592ms


 

The complete tracert process is as follows:




The source portfirst sends three UDP packets with the TTL value of 1 to a remote device. Bydefault, the first packet uses port 33434 as the receive port on the targetdevice. Port numbers in ascending order are used to send the following packets.For example, the second packet uses port 33435 as the receive port, and thethird packet uses the port numbered 33436 as the receive port. The TTL value of1 causes the UDP packets to "timeout" as soon as the packets hit thefirst Device along the path; the Device then responds withan ICMP TTL Timeout message indicating that the UDP packets have expired. Thesource sends another three UDP messages, each with the TTL value of 2, whichcauses the second Device to reply with ICMP TTL Timeout messages.This process repeats until the UDP packets reach the destination of the path.


If these UDP packets are sent to an invalid port at the destination, ICMP Port Unreachablemessages will be returned, indicating that the port is unreachable and the tracert process has stopped. The tracert process collects information about the path along which packets travel to the destination.

The maximum TTLvalue for a UDP packet is 30. Each time no response is received within the configured timeout period, the source node displays messages indicating that the UDP packets expire. If TTL values in UDP packets expire, the destination is unreachable, and the tracert test fails.
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All Answers
Popeye_Wang
Popeye_Wang Admin Created Sep 17, 2019 06:25:02 Helpful(0) Helpful(0)

Hi Sprout,
Thisis related to the tracert process. By default, the source port sends three UDPpackets in a trace test. If you run the tracert command on a Huawei device, you can use the parameter -q  to specify the number of sent packets.
For example:


<HUAWEI> tracert -q 5 10.10.0.10


traceroute to 10.10.0.10 (10.10.0.10), hops max: 18, packetlength: 40,press CTRL_C to break


1 10.3.112.1 (10.3.112.1) 17 ms 17 ms 27 ms 17ms 20ms


2 10.32.216.1 (10.32.216.1) 19 ms 19 ms 19 ms 19ms 18ms


3 10.32.168.22 (10.32.168.22) 20 ms 39 ms 39 ms 27ms 30ms


4 * * * * *


5 * * * * *


6 10.10.0.10 (10.10.0.10) 339 ms 279 ms 279 ms 600ms 592ms


 

The complete tracert process is as follows:




The source portfirst sends three UDP packets with the TTL value of 1 to a remote device. Bydefault, the first packet uses port 33434 as the receive port on the targetdevice. Port numbers in ascending order are used to send the following packets.For example, the second packet uses port 33435 as the receive port, and thethird packet uses the port numbered 33436 as the receive port. The TTL value of1 causes the UDP packets to "timeout" as soon as the packets hit thefirst Device along the path; the Device then responds withan ICMP TTL Timeout message indicating that the UDP packets have expired. Thesource sends another three UDP messages, each with the TTL value of 2, whichcauses the second Device to reply with ICMP TTL Timeout messages.This process repeats until the UDP packets reach the destination of the path.


If these UDP packets are sent to an invalid port at the destination, ICMP Port Unreachablemessages will be returned, indicating that the port is unreachable and the tracert process has stopped. The tracert process collects information about the path along which packets travel to the destination.

The maximum TTLvalue for a UDP packet is 30. Each time no response is received within the configured timeout period, the source node displays messages indicating that the UDP packets expire. If TTL values in UDP packets expire, the destination is unreachable, and the tracert test fails.
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sebr
sebr Created Sep 17, 2019 06:33:15 Helpful(0) Helpful(0)

Hi there,

@Popeye_Wang gives a great explanation of the underlying traceroute process, but to answer your question the three columns (or more depending on the parameter supplied, ie, -q 5) display the to round trip time of each UDP packet sent at each TTL increment.

cheers,
Seb.
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Network%20Engineer%20contractor%20based%20in%20the%20UK.%20%0AI%20have%20worked%20in%20the%20networking%20field%20for%20the%20last%209%20years%20and%20Linux%20servers%20before%20that.%20%20My%20main%20areas%20of%20expertise%20are%20routing%2C%20switching%2C%20firewalls%20and%20network%20automation%2F%20programming.
Sprout
Sprout Created Sep 17, 2019 07:03:32 Helpful(0) Helpful(0)

Posted by sebr at 2019-09-17 06:33 Hi there,@Popeye_Wang gives a great explanation of the underlying traceroute process, but to answer ...
Thank you for your explanation.
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