How does traceroute work

[Sumanth N]

I just want to know how trace route works on HP UX 11.11.

[Arunvijai_4]

# man traceroute should give enough information for you..

-Arun

[Adisuria Wangsadinata_1]

Hi,

Check the manual page of traceroute :

# man traceroute

And these are technical document related with traceroute :

http://www2.itrc.hp.com/service/james/search.do?searchtext=traceroute&searchcriteria=allwords&searchtype=SEARCH_TECH_DOCS&rn=25&presort=rank&x=27&y=11

Hope this information can help you.

Cheers,
AW

[Muthukumar_5]

http://www.inetdaemon.com/tools/traceroute/definition.html

hth.

[Arunvijai_4]

One more link,

http://www.webopedia.com/TERM/T/traceroute.html

-Arun

[VEL_1]

Hi,

The following links provieds HOWTO works with detailed diagram:

http://www.freesoft.org/CIE/Topics/54.htm


Thanks.

[Sumanth N]

Thanks for the reply.

does traceroute fail if there is a Virtual interface (configured using ifconfig) on top of primary IP.

i have configured an Virtual interface and i have given some IP(say dummy)

traceroute
gives the following message,

traceroute: Warning: Multiple interfaces found; using 134.21.113.23 @ lan0:2
1 * * *
2 * * *
.
.
.
30 * * *


I think this is becuase the dummy IP on the virtual IP.
but traceroute works if i give -i option and the primary IP.
traceroute -i lan0
works.
Is it limitation of traceroute becuase not able to differentiate b/w primary and secondary IP.

[Stuart Powell]

Sumanth,

I had a similar question about traceroute a few months ago. I was told that at 11.00 HP changed traceroute so that you HAVE to specify the LAN interface. That is was not obvious to me when I read the man pages.

Stuart

[HGN]

Hi

Stuart is correct you need to specify which interface you need to use to do a traceoute if you dont specify it picks some interface.

Rgds

HGN

[Don Mallory · Accepted solution]

Interestingly enough, all of the responses so far have been about the specific command for traceroute. When I saw this question, I wondered if you meant exactly what the traceroute command does. Since nobody else has answered this part...

It takes an ICMP Echo request packet and sets the TTL (time to live) field to 1. When the recipient receives the packet and decrements it to 0, a reply packet is sent to the originator. This is the first hop.

The TTL is then set to 2, and the request is sent again. Response from recipient where the TTL was decremented to 0 is sent back.

This continues until the packet reaches it's eventual destination.

Most versions of traceroute will attempt to send the packet 3 times per hop, although this is configurable.

So, it's like shooting flares in the dark, each one going a little bit farther.

Don

[Tim D Fulford]

Don beat me to it... and a very good explaination too.

The only bit I think is missing is every time it fails to reach the final host/address the returned packet gives the IP address of where it got to, so the system is able to piece together where it went on the 1st, 2nd, 3rd and subsequent hops and how long it took to get there....I thought this was rather neat when I heard it..

Tim

[Sumanth N]

Thanks for all the replies.