On 27/03/14 19:13, Phoebe Buckheister wrote:
>> Is it possible for a device to co-ordinate more than 1 WPAN on the same
>> PHY, beacon enabled or beaconless?
>> If so is it possible to bridge or route from one WPAN to another within
>> a device over the same PHY?
>> Can a slave join more than one WPAN, again using the same PHY?
> Theoretically yes on almost all accounts, practically on none right now
> and probably ever. To be part of multiple WPANs, a device *must* send ACKs
> in time for those frames that request them, coordinators and
> non-coordinators alike. That is hard (if not impossible) to get working
> correctly within the specified time frames without any hardware support or
> an RT kernel (and even then it's tough for the faster PHYs). Better don't
> count on it.
>
> That "multiple associations per PHY"-thing was actually discussed to some
> length a week or two back on this list and netdev. My takeaway from that
> is "not now, not ever", and I intend to completely remove the ability to
> register multiple WPANs per PHY in the near future because all currently
> possible uses of multiple WPANs as possible now can be implemented without
> breaking netdev semantics and with actual guarantees in a slightly
> different manner.
>
> Bridging is entirely impossible due to the ACK frames, unless you find it
> acceptable to incorrectly have a device assume that a frame was received
> by the intended recipient when that hasn't yet happened. Routing is not
> defined for 802.15.4, but upper layers (say 6lowpan/IP) can do that just
> fine.
>
Hi Phoebe,

Thank you for the swift response it has given my a lot to think about.  
I remember the discussion and like you I was in favour of removing the 
slave list.  But as chance would have it I think we may actually need it 
now or some other method of multiple WPANs per PHY.  I need to have a 
think especially with regards to ACKs as this is something I haven't 
thought about.
I don't suppose you can you expand on why bridging is impossible due to 
the ACK frames?



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