North American Network Operators Group

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Re: ATM Question

  • From: Thomas P. Brisco
  • Date: Fri Oct 06 09:10:19 2000

	We were seeing something similar yesterday (and yup -
it's still there today).  We also noted that if you turn on the
record-route options, then your problem will disappear (I suspect
packet options may cause delivery to be ok - though while the RR
option helps, DF doesnt, but "timestamp" will).  We're not seeing
packet loss in any other scenario.  I noticed, suspiciously, that
there is always a very "hockey toothed" (every other packet) pattern
in the lossage (load balancing onto a botched circuit?).

	Things I've played with:
	* size		50%	(tried 800, 1200, 2500)
	* DF		50%
	* RR		100%
	* pattern	seems to be generally 50%
	* timestamp	100%
	* TOS		50%
	We've opened up a case with cisco ... seems pretty
bizarre, but could it be the ATM switch?
	As long as we're not using the source address of
the ATM network - things are fine (e.g. sourcing off of
the loopback, going one hop back, etc).

						- Tom

On Fri, 6 Oct 2000, Richard Inhand wrote:

> Date: Fri, 6 Oct 2000 04:50:10 -0700 (PDT)
> From: Richard Inhand <[email protected]>
> To: [email protected]
> Subject: ATM Question
> I'm currently looking into a weird problem at an ATM
> peering point on the West Coast, when I ping from my
> peer router to any of my peers I get some but not
> total packet loss, when I ping from one router back or
> use the loopback interface as source things are fine.
> Whereas, with all my other ATM peering point routers,
> for example at MAE-EAST I can ping my peers cleanly
> from the same router. This isn't (to my knowledge)
> affecting traffic just wondering why this strange
> phenomenon should occur only in the one place.
> Any body else had any similar problems?
> Richard Hand
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