traceroute output?

Thread Tools Search this Thread
Top Forums UNIX for Dummies Questions & Answers traceroute output?
# 1  
Old 05-27-2002
traceroute output?

I understand the concept of traceroute - can anyone explain the output to me e.g. 39ms 39ms 39ms are these the times for each trip it takes? Assuming each machine is pinged 3 times.

and how does the RTT work? Is this the time it takes from one machine to another because it doesn't look like it's accumulative. Any basic explanation would be lovely thanks.
# 2  
Old 05-27-2002
The traceroute program constructs an ip datagram addressed to the destination that you specify. But it sets the TTL to one and sends it out. The first router in the path to the destination gets this datagram and decrements the TTL. When is sees that the TTL just became zero, it discards the datagram. It also sends ICMP error back to the source. When traceoute gets the ICMP error, it calculates how long this took and displays the result. It repeats this process two more times. So you get three numbers for the first hop.

Next it sets the TTL to 2 and send out three more datagrams, and prints out 3 more results. This is line two of the display.

And so on, until it reaches the destination or it reaches the max hops.

Those numbers that are being displayed are called the RTT's for each hop.

No the numbers are not cumulative. Routers, especially in a WAN environment have variable loads. What you want to do is look for anything unusual. To know what "unusual" is, you need to run traceroute a lot when stuff is working ok.
# 3  
Old 05-28-2002
Smilie This utility is intended for use in network testing, meas-
urement and management. It should be used primarily for
manual fault isolation. Because of the load it could impose
on the network, it is unwise to use traceroute during
normal operations or from automated scripts.
# 4  
Old 05-28-2002
Perderabo - is the RTT the time it takes for my machine to send the IP datagram and retrieve an ICMP packet back?

If so, can I increase the number of packets sent so I can calculate a median value for RTT to each server in the traceroute?

If I take the mean then the stats might be way off the mark because I have seen some RTT's that are very extreme.
# 5  
Old 05-28-2002
raju - can you explain a bit more about the network loading issues when using traceroute in an automated script?

Why is the network loaded?
Are the ICMP packets a problem?
Does traceroute have much effect on the network?
What other issues does traceroute product?

NB: I am looking to use traceroute in a script as part of a trail test on a network.
# 6  
Old 05-28-2002
The traceroute program knows when it sent the test datagram and it knows when it gets the ICMP error. And yes, the RTT is the difference between the two. But traceroute is not the kernel. Traceroute can't tell when the error arrived at the local host. It has to wait to run just like any other program in a timesharing system.

No you can't increase the number of packets, it is stuck at three.

As you have noted, the standard deviation is so high that taking the mean would be silly. Acquiring enough data to produce a useful mean is not possible. If you try, you will drive network performance way down.

For the most part, I agree with raju. Only I do think that you should run netstat several times a day so you have baseline. So I do think some running of traceroute (manually) during normal operations is appropriate. But for the most part, traceroute is intended to diagnose network malfunctions.
# 7  
Old 05-28-2002
Thanks Perderabo, didn't consider the kernel in all this. I think I'll have a deeper search of Traceroute on the man pages, I obviously don't know enough about it.

I don't think the network perfomance will be much of an issue as the traceroute will not be designed to flood the network just a snap shot to collate and contribute to a baseline and highlight any areas where latency might be occurring.

NB: i did find out that the packets aren't fixed and can be increased ( i have to do that in my script ) using the -q flag Smilie
Login or Register to Ask a Question

Previous Thread | Next Thread

9 More Discussions You Might Find Interesting

1. IP Networking


I have some question about traceroute: 1. Can we hide our computer from traceroute? (2 Replies)
Discussion started by: budiantho_indra
2 Replies

2. UNIX for Dummies Questions & Answers

Traceroute Query

Hi guys, Quick traceroute query. As part of some research I'm doing I need to send a traceroute to an equal number of IPv4 and IPv6 addresses on the net and basically capture the number of hops, and intermediate IP addresses from the traces. This all needs to be automated as there are... (2 Replies)
Discussion started by: churchill
2 Replies

3. Shell Programming and Scripting

Traceroute script weird output

This script is giving weird output #!/bin/bash NETPATH=(`/bin/traceroute -n | awk '{print $2}'`) for i in "${NETPATH}" do echo $i done The output: to (7 Replies)
Discussion started by: thumbs
7 Replies

4. UNIX for Advanced & Expert Users

Explain and example of traceroute.

Hi Colleagues, Somebody can explain me and send me examples about traceroute, I know is for network but I need anderstand your funcionality. Thank you for advanced. (2 Replies)
Discussion started by: systemoper
2 Replies

5. UNIX for Dummies Questions & Answers


Good afternoon Can anyone explain traceroutes to me and when it would be necessary/what situations would call one to use it? (2 Replies)
Discussion started by: iamnew2solaris
2 Replies

6. Shell Programming and Scripting

help with ksh parsing traceroute output

Good day. I am doing an enq -WA (AIX), to get a list of the print queues, I then compare that to the /etc/hosts file to 'match' the IP address associated with the print queues. What I want to do is to run a traceroute with up to 5 hops, and perform an output to a file with some "specific items".... (0 Replies)
Discussion started by: smurphy_it
0 Replies

7. IP Networking

Puzzling Traceroute output

This is the output that I get every so often when trying to do a traceroute to the web server whenever it's inaccessible: traceroute to (, 30 hops max, 40 byte packets 1 ( 2.625 ms 2.840 ms 2.968 ms 2 (6 Replies)
Discussion started by: gaspol
6 Replies

8. UNIX for Advanced & Expert Users


Hi, Can any one suggest me an add on feature for the traceroute command. Thanks in advance. Regards, Selvi (4 Replies)
Discussion started by: salvi
4 Replies

9. Programming

how we can use traceroute

how we can use traceroute in unix c so how we can get the output of traceroute command in c thank u,inadvance sree (3 Replies)
Discussion started by: phani_sree
3 Replies
Login or Register to Ask a Question