[165348] in North American Network Operators' Group
Re: IP Fragmentation - Not reliable over the Internet?
daemon@ATHENA.MIT.EDU (Benno Overeinder)
Fri Aug 30 10:37:27 2013
Date: Fri, 30 Aug 2013 16:36:39 +0200
From: Benno Overeinder <benno@NLnetLabs.nl>
To: Randy Bush <randy@psg.com>
In-Reply-To: <m2ob8fjspp.wl%randy@psg.com>
Cc: nanog@nanog.org
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
On 08/30/2013 01:58 PM, Randy Bush wrote:
>> In a study using the RIPE Atlas probes, we have used a heuristic to
>> figure out where the fragments where dropped. And from the Atlas
>> probes where IP fragments did not arrive, there is a high likelihood
>> the problem is with the last hop to the Atlas probe.
>
> i wonder if this is correlated with the high number of probes being
> behind nats.
That would be a viable explanation, although we have not tried to
fingerprint the probes to figure out if this was true.
If we will rerun the experiments in the future, we should spent more
effort into identifying the router/middlebox that is giving the IP
fragmentation problems (drops or blocking PMTUD ICMP).
-- Benno
--
Benno J. Overeinder
NLnet Labs
http://www.nlnetlabs.nl/
