[mat-wg] New on RIPE Labs: Further Virtualisation Testing for RIPE Atlas Anchor
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Romeo Zwart
romeo.zwart at ripe.net
Mon Sep 16 12:39:18 CEST 2013
Hi Randy, On 13/09/16 01:59 , Randy Bush wrote: >> https://labs.ripe.net/Members/romeo_zwart/LuigiCorselloAtlasanchorvirtualisationfinalreport.pdf > > nice masters level work, which i presume it was. of course, the devil > is in the details, and he seemed to be dealing with a lot of devils. Thanks for taking the time to review. I will forward your comments, I am sure the researcher will be pleased with your constructive criticism. [...] > i was worried by > > In fact, the first TTM node for time monitoring (tt97.ripe.net) > resided in a different VLAN than the POC and had an average delay > of about 1100μsec! That was certainly not good enough to measure > sub millisecond time accuracy and was replaced by tt999.ripe.net > installed in the same VLAN as the POC. > > ntp is designed to be pretty insensitive to rtt. so this either scares > the hell outta me about ttm, is a misunderstanding, or miscommunication. > i would love to see more analysis of this. This is a misunderstanding and probably only reflects a very early view of the researcher on the topic. I don't believe it was intended to comment on the quality of the TTM mechanism. :) WRT you other question about more work along these lines on TTM. I think it's unlikely we will follow this up further. The researcher has moved on the greener fields in the mean time and a lot of work on TTM has been done in the early 2000's and before, see e.g. [1]. Although that particular reference is not specifically looking TTM accuracy. > side note: it would have been nice if he had run openvz and kvm on > something less paleolithic than centos. > > but my compliments to the researcher and to the ncc for funding him. > useful work. Thanks for that comment. I will pass it on. :) > randy > [1] http://www-nas.et.tudelft.nl/people/Piet/papers/PAM2002.pdf
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