allocating lowest 64 bits from WGS84

[Eugen Leitl]

On Tue, Jan 11, 2011 at 09:18:38PM -0800, George Bonser wrote:
> > and made sure that bit 70 is set to zero, indicating that the address
> > is not derived from a globally unique token e.g. MAC address, you
> > should be fine.
> 
> Yeah, one has to figure that more than one device could possibly get the
> same x,y,z coordinates if they are on the shelf next to each other.

Yes, I would have prefered to resolve a cubic micron, but IPv6 doesn't
have spare space for that. Still, 24 bits gives you a resolution of about
2 meters on Earth surface at equator. GPS typically has an error ellipsoid 
larger than that, so the nodes will unlikely to obtain the same three 
numbers by a measurement (unless via a long-term measurement under 
optimal conditions), and furthermore they would be probably communicating 
with each other, ideally be able to determine their mutual distance by a 
time of flight measurement (you do not need GPS radio if all nodes can
do mutual time of flight triangulation, with only a few absolute
reference points), or generally agree to jiggle their position by a bit 
until they no longer collide.

So I don't think it's a real problem. By the time nodes are unformly
spaced less than 2 m apart IPv6 as we know it won't exist, anyway.

-- 
Eugen* Leitl <a href="http://leitl.org">leitl</a> http://leitl.org
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