[8023-POEP] Classification Ad Hoc: Summary from 2-22-06

["Clay Stanford (LTC)" <claystanfordltc@xxxxxxxxx>]

Thanks to Steve Robbins for this summary.  I have
added some to it.  We can verify this list tomorrow.

Things the group seems to agree on:
1.	Backward compatibility with 802.3af is required. 	
2.	Mutual identification is required:
a.	An AT-PD must be able to distinguish between AF-PSE
and AT-PSE 
b.	An AT-PSE must be able to distinguish between AF-PD
and AT-PD. 
3.	Classification power range is roughly 2W (see issue
1 below) to 100W. 
4.	The classification scale should be roughly
logarithmic, or log like. 
a.	Certainly logarithmic for high power classes 
b.	Probably linear for low power classes 
5.	Any advanced power management issues such as
negotiation, should be done with Layer 2.  (Layer 2
definitions are outside the scope of this ad hoc.)
6.	Layer 2 power management is optional.  
7.	Before a 4-pair PSE grants power to a 4-pair PD
operating above XX watts, the PSE must first verify
that all 4 pairs are present and connected to the
4-pair PD.  If the PSE only detects two pair are
present, the PSE will only grant power up to XX watts.
 XX watts is the maximum power allowed in a 2-pair
system.  I.E., any time the PSE wants to use all 4
pairs, it must first verify that all 4 pairs go to the
same PD. 
8.	Classification is mandatory 
9.	Class policing will remain optional.
10.	Classification method should support midspan and
endpoint PSEs. 

Issues the group felt must be discussed further:
1.	What should the low end of the power range be? 
(See item 3 above.) 
2.	Should we use worst-case or statistical analysis to
try to calculate utilization, and the number of
classes required? 
3.	Should 4P verification be done during
classification or detection? 
4.	Should the PD have one signature (visible on all 4
pairs) or 2 separate signatures (one on Alt-A and the
other on Alt-B)?
5.	Should 4-pair systems be treated as two autonomous
2-pair systems?
6.	Should a 4-pair PD that fails to get power provide
user with a two-level failure indication, one for an
AF-PSE and another for a 2-pair AT-PSE?
7.	How many classes should be provided?



Subjects for Future Discussions
Power supply utilization


Misc
Yair provided a Preliminary Comparison Table.
Yair referenced a previous work on power supply
utilization
http://grouper.ieee.org/groups/802/3/poep_study/public/jul05/darshan_2_0705.pdf





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