Short-circuited traceroutes on FIOS

Thu Dec 12 13:55:28 UTC 2019

Yeah, and what do you do with a traceroute that looks like this….  (ip address intentionally changed)

C:\>tracert -d -w 1 1.2.3.4

Tracing route to 1.2.3.4 over a maximum of 30 hops

  1     8 ms     5 ms     5 ms  96.8.191.129

  2     *        *        *     Request timed out.

  3     *        *        *     Request timed out.

  4     *        *        *     Request timed out.

  5     *        *        *     Request timed out.

  6     *        *        *     Request timed out.

  7     *        *        *     Request timed out.

  8     *        *        *     Request timed out.

 9     *        *        *     Request timed out.

10     *        *        *     Request timed out.

11     *        *        *     Request timed out.

12     *        *        *     Request timed out.

13     *        *        *     Request timed out.

14     *        *        *     Request timed out.

15     *        *        *     Request timed out.

16     *        *        *     Request timed out.

17   267 ms   202 ms     *     1.2.3.4

18   205 ms   175 ms     *     1.2.3.4

19   160 ms   233 ms     *     1.2.3.4

20   199 ms   201 ms     *     1.2.3.4

21   213 ms   206 ms     *     1.2.3.4

22   165 ms   158 ms     *     1.2.3.4

23   237 ms   158 ms     *     1.2.3.4

24   158 ms   290 ms     *     1.2.3.4

25   158 ms   160 ms   158 ms  1.2.3.4

Trace complete.

C:\>

From: NANOG [mailto:nanog-bounces at nanog.org] On Behalf Of Etienne-Victor Depasquale
Sent: Thursday, December 12, 2019 1:18 AM
To: Valdis Klētnieks
Cc: nanog at nanog.org
Subject: Re: Short-circuited traceroutes on FIOS

Traceroute is becoming more and more an expert's tool because interpretation of its results isn't straightforward.

I had written a paper last year and mentioned its misuse in academia in the context of estimating the number of energy-consuming devices between a source and a destination. 

Traceroute was being used to count the number of physical router devices from the hop count, notwithstanding the use of MPLS in domain cores.

To an external observer, this results in significant underestimation of the energy consumption in the path from source to destination.

On Thu, Dec 12, 2019 at 12:51 AM Valdis Klētnieks <valdis.kletnieks at vt.edu> wrote:

On Wed, 11 Dec 2019 19:26:09 +0200, Saku Ytti said:
> On Wed, 11 Dec 2019 at 19:14, Rob Foehl <rwf at loonybin.net> wrote:
>
> > Support claims that it was a mistake, but it's also been 15+ months and
> > it's pretty deliberate behavior.  Draw your own conclusions...
>
> TTL decrement issues are fairly common across multiple vendors and hw,
> can be sw can be hw limit

Yes, but you need to screw up gloriously on the decrement if you think that
"I decremented and it's zero now" means "therefor it must have been addressed
to me, so I'll send an ECHO REPLY instead of TTL EXCEEDED".

-- 

Ing. Etienne-Victor Depasquale
Assistant Lecturer
Department of Communications & Computer Engineering
Faculty of Information & Communication Technology
University of Malta

Web. https://www.um.edu.mt/profile/etiennedepasquale

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