Help me make sense of these traceroutes please

Josephson, Marcus Marcus.Josephson at Level3.com
Thu Dec 26 16:21:45 UTC 2013


Start at slide 50:

This is documented further by the following Nanog presentation. http://www.nanog.org/meetings/nanog47/presentations/Sunday/RAS_Traceroute_N47_Sun.pdf

-Marcus


-----Original Message-----
From: Jimmy Hess [mailto:mysidia at gmail.com] 
Sent: Wednesday, December 25, 2013 10:28 AM
To: Martin Hotze
Cc: nanog at nanog.org
Subject: Re: Help me make sense of these traceroutes please

On Wed, Dec 25, 2013 at 8:03 AM, Martin Hotze <m.hotze at hotze.com> wrote:
>
> > On 2013-12-25 00:16, Sam Moats wrote:
>
...

> > You are likely seeing the effects of asymmetric routing.
> . .. or the effect of passing traffic through NSA infrastructure.
>
>
Ah... NSA.   That's probably it.
So much for my theory of a Router virtual chassis  straddling  the atlantic.

 or the extra kinetic energy carried by the overseas-bound packet took longer for the router to absorb and rebound with an ICMP.





But in all seriousness --- what is probably happening here, is  the result of extra  "hops"  that don't show up in  traceroute.
MPLS tunnels could well fit the bill.



Other things to consider when latency seems sensitive to destination IP --- are preceding device in the traceroute might also have multiple links to the same device;  with one link congested and some form of IP-based load sharing,  that happens to be the toward-overseas link.



> SCNR, #m

--
-JH



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