allocating lowest 64 bits from WGS84

[Mark Smith]

On Tue, 11 Jan 2011 10:45:50 +0100
Eugen Leitl <eugen at leitl.org> wrote:

> Assuming I assign my MAC from physical host WGS 84 GPS 
> position fixes (e.g. 24 bit for each long/lat, no alt, 
> 48 bit total), and add 16 bit for altitude position 
> part to obtain the 64 bit host address part, 
> would that break any IPv6 built-in assumptions?
> 

As long as you didn't conflict with any of these -

"Reserved IPv6 Interface Identifiers"

http://tools.ietf.org/html//rfc5453

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.

> (Obvious application: e.g. wireless node mesh address
> allocation).
> 
> Assuming above doesn't break things. If some of the nodes
> are mobile (which means they would slowly change their
> 64 bit host address part), and one would use mask based
> geographic broadcast to match a given node or nodes in
> a particular area, this is no longer IPv6 as we know it,
> correct? 
> 

Sounds more like an application for multicast. A brief read of the
abstract and intro of the following sounds like it might be just what
you want -

RFC 4489 - Link-Scoped IPv6 Multicast
http://www.ietf.org/rfc/rfc4489.txt

"... The extension allows the use of
   Interface Identifiers (IIDs) to allocate multicast addresses.  When a
   link-local unicast address is configured at each interface of a node,
   an IID is uniquely determined.  After that, each node can generate
   its unique multicast addresses automatically without conflicts."

An alternative might be to assign IPv6 prefixes to geographic regions
and then use multicast addresses derived from the prefixes values as
described in RFC3306.

HTH,
Mark.






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