Simon Duquennoy <[email protected]> wrote: > 1) As we're hashing the MAC address, the cells coordinates should be > uniformly distributed regardless of the input. Or are you concerned about the > hash function we selected, SAX? (which might indeed perform poorly in the > case of consecutive 2-byte addresses!). My implementation only supports > EUI-64 so far, so I haven't experimented with 2-byte addresses.
I don't know; I'm saying we'd better check.
Two addresses that differ by one bit is just not a lot of entropy to put
*into* the hash. No hash function can extract more entropy than you put in.
What it can do is smear the entropy around, and the question is how well does
it work in practice?
> 2) If we make the hash function configurable, with the help of the JRC, we
> could ensure that nodes all get a unique slot assigned. If there is
interest
> I'm happy to include this in the draft.
I think that hash function, if you want to make it configurable, should be
done through DIO Options, not through the JRC. If randomized 2-byte
addresses are better, it would be good to know that.
> 3) I don't think so, because nodes may have outdated views of their
> neighbor's rank. I'm assuming what you have in mind is to provision more
to
> nodes close to the root. One possible way to handle dynamic loads would
be to
> use the frame pending bit in 802.15.4 frames, and schedule consecutive
slots
> on-demand. Thoughts?
A child will always know what the parent's rank is, and a parent will always
know what rank it announced to the child in the last DIO. The child could
have missed a new DIO announcing a new rank, it is true. I think that we
could make it work.
Yes, provisioning more bandwidth closer to the root is one thought I had.
The pending frame bit could work to extend the duration of the slot, but
that won't help if that slot is allocated to another child!
--
Michael Richardson <[email protected]>, Sandelman Software Works
-= IPv6 IoT consulting =-
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