Cogent NOC

Ken Chase math at sizone.org
Wed Dec 14 20:08:52 UTC 2016


I was going to reply and repeat Job Snijders's indications of Thu, 7 Jul 2016 to

 Please review the excellent presentation from RA{T,S}:
    https://www.nanog.org/meetings/nanog47/presentations/Sunday/RAS_Traceroute_N47_Sun.pdf
    https://www.youtube.com/watch?v=a1IaRAVGPEE

esp the pdf there, but in this case Randy's mtr does do a ping to the last
hop. He did have 4.1% pl to the endpoint for his specific setup and
current gear/route/etc.

However, I go through the same hostname'd router he does (he didnt provide an
ip, but paris-traceroute doesnt show me load balancing, at least visibly), and
I only get 0.3% pl. (Though, my immediate upstream DSL provider's router is giving
me 0.2% pl, so who knows what that 0.3% means at the far end, really.)

Without bidirectional concurrent mtr's (one from cogent back to him at the
same time), it's quite hard to say what's going on. Even then that's no guarantee
of diagnosis.

Here's just the most recent thread with some depth on how to read traces and packetloss:

http://seclists.org/nanog/2016/Jul/155

the whole thread is useful. But is only one of the dozens of times this has come
up on nanog. (Again: read that pdf!)

/kc


On Wed, Dec 14, 2016 at 05:53:56PM -0200, Kurt Kraut said:
  >Hello,
  >
  >
  >mtr packet loss column has no scientific precision and should not be
  >considered. It is not mtr fault but forwarding routers have a low priority
  >to respond to ICMP requests. The only way you can prove there is a problem
  >is a end to end ping, the regular ping command, not mtr.
  >
  >
  >Best regards,
  >
  >
  >Kurt Kraut
  >
  >2016-12-14 17:16 GMT-02:00 Randy <amps at djlab.com>:
  >
  >> Hi all,
  >>
  >> Anyone beyond front line support at cogento on list?
  >>
  >> Nanog is the last place I'd look for assistance but it seems support over
  >> at cogentco is not nearly what it used to be.
  >>
  >> Example MTR to cogen't own website (support doesn't utilize or understand
  >> MTR at all apparently):
  >>
  >> Host                                  Loss%   Snt   Last   Avg  Best  Wrst
  >> StDev
  >>  1. x.x.x.x                             0.0%   196    0.5  11.7   0.3
  >> 186.8  35.2
  >>  2. x.x.x.x                             0.0%   196    0.6  10.2   0.4
  >> 226.3  36.2
  >>  3. 38.88.249.209                       0.0%   196    0.9   1.1   0.7
  >> 17.7   1.2
  >>  4. te0-0-2-3.nr13.b023801-0.iad01.atl  0.0%   196    1.0   1.0   0.8
  >>  2.0   0.1
  >>  5. te0-0-0-1.rcr22.iad01.atlas.cogent  2.0%   196    2.1   1.9   1.0
  >>  3.3   0.4
  >>  6. be2961.ccr41.iad02.atlas.cogentco.  2.6%   196    1.8   2.1   1.1
  >>  3.8   0.5
  >>  7. be2954.rcr21.iad03.atlas.cogentco.  2.6%   196    2.0   2.3   1.2
  >>  9.4   0.7
  >>  8. be2952.agr11.iad03.atlas.cogentco.  0.5%   196    2.7   2.6   1.5
  >>  6.8   0.6
  >>  9. cogentco.com                        4.1%   196    2.1   2.0   1.0
  >> 16.8   1.1
  >>
  >> Pretty much the same to anywhere.   Packet loss begins at rcr22.iad01 and
  >> propagates all the way down the line.   Worse during peak hours, gone late
  >> at night.
  >>
  >> After three days of no email response for my ticket, I called and after an
  >> hour of my life I want back, front line support cannot reproduce the loss.
  >>  Final conclusion: "Your host is dropping packets".
  >>
  >> --
  >> ~Randy
  >>

--
Ken Chase - math at sizone.org Guelph Canada


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