[Cerowrt-devel] [Make-wifi-fast] Fwd: [tsvwg] Comments on draft-szigeti-tsvwg-ieee-802-11e

[Sebastian Moeller]

Oh, boy,


On Jul 23, 2015, at 09:49 , Alan Jenkins <alan.christopher.jenkins at gmail.com> wrote:

> On 23/07/15 08:44, Jonathan Morton wrote:
>> 
>> Link to the spec?
>> 
>> - Jonathan Morton
>> 
>> 
> 
> https://datatracker.ietf.org/doc/draft-szigeti-tsvwg-ieee-802-11e/


	Not that I am a domain expert, but the whole web of slightly different versions of the same madness are quite amusing ;) What seems clear to me is that the wealth of 64 possible combinations looks a lot like a slippery slope (or better like a full blown slip and slide). 
	As far as I can see, hardware folks and MPLS opted for 3 bits maximum (I take it that wifi is actually 2 bits only), so what real use is in schemes using more than 8 different states beyond that mapping 12/16/64 to 8 is a fun exercise in bike-shedding… 

But since bike shedding is fun here is my “I am not even confused by partial knowledge” proposal for a 3+1bit marking scheme:

1) take the most significant 3 bits to deduce the CS equivalent (willfully ignoring the lower 3 bits) which will be treated as priority levels
2) decide were in the 3 bit range the “normal should be”, say 3 for example (to allow simplistic mapping to 2bit patterns)
3) extend by 1 bit at the end to get to 4 bits (I guess that would be shift by 1 bit?)
4) remark/remap the CS0 equivalent as “normal” + 1 (alternatively remap CS0 to “normal” and the CS that used to live there to “normal”+1)

Heck even just staying at 3 bits and just remarking CS0 to CS3 should do the trick, of putting in a lower priority class below the default best-effort traffic and still keep 802.11 mappings semi-working

And then just treat these as 8 different priority levels with the number coding the priority order using Jonathan’s approach of pairing higher priorities with lower guaranteed bandwidths allotments.
Blissfully ignore the proposed differentiation of the lower 3 bits until there is proof that they are actually helpful...


	I really wonder what the whole brouhaha is all about; wikipedia tells me ( https://en.wikipedia.org/wiki/IEEE_802.11e-2005 ) that Enhanced distributed channel access (EDCA) is sort of a best effort QoS system (what?) and that HCF Controlled Channel Access (HCCA) is where things should be going. Because then the AP manages all air time and all stations and the AP can do “normal”/high level priority queueing into the wifi adapters best-effort queue without the need for the “crazy" that is implementing media access as a race (especially with many clients that just does not sound like an efficient approach). But then I do not claim to be an expert in these matters.

Best Regards & sorry for the gantlet above
	Sebastian

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