[sugar] 65-node simple mesh test (and counting... ;-)
billmcc at nortel.com
Fri May 9 15:39:30 EDT 2008
what format is the data in, is this pcap?
From: devel-bounces at lists.laptop.org
[mailto:devel-bounces at lists.laptop.org] On Behalf Of Polychronis
Sent: Friday, May 09, 2008 3:35 PM
To: Michael Stone; OLPC Development
Subject: Re: [sugar] 65-node simple mesh test (and counting... ;-)
Michael Stone wrote:
> Data Questions:
> * Are the measurements used to make the display of 'distributions of
> profile arrival rate vs. time' produced from timestamps of profile
> arrival as recorded by all the laptops or by some smaller set of
All XOs got synced clocks (by means of a broadcast packet that sets the
time on all machines, providing a clock skew in the neighborhood of a
single second). Then, timestamps of profile arrivals were collected from
all 65 nodes, each reporting arrivals for the other 64 nodes.
> * What was the general nature of the connectivity graph of the 65
> laptops? Did it change over time?
The nodes are lying in the Garden area of 1CC, and they were
consistently 1-hop away from all other nodes (full mesh network) all the
> * Did you take any measurements of background network traffic?
No, but I should have. However, we can all agree that 1CC is relatively
> * Do you have any new insight into how the presence of NM (or of
> software on top of it that depended on it) was killing your
My understanding is that the NM is trying its best to make ends meet in
terms of what the user needs (connect to an AP/XS/mesh ?) and what
connection is most "reliable" (I assume that an AP is considered more
"reliable" than the mesh, but I honestly doubt it!). As a result, the NM
may occasionally make the bold move to move from one connection type to
another, breaking all existing "connections" (quoted because there are
no TCP-like connections in my experiments), leaving stale information at
various points of the software stack (eg. mesh view).
> At any rate, thanks for this good work!
> P.S. - When you produce measurements like these, please include links
> to the raw data.
The raw capture is here:
MIT Media Lab
Tel: +1 (617) 459-6058
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