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RUNNING SUMMARY OF THE IEEE 802.3at CLASSIFICATION AD HOC MEETING (See attachment for color formated version of summary) Notes: Items in orange may not be universally agreed upon. Text in blue are comments by attendees. Text in green is added by Clay. 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 1-2W up 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. Comment from Yair with edits by Clay: Other option to consider for dealing with 4-pair power: -PSE limits the power per any 2P to XX watts. -PSE performs detection and classification for any 2P. -If the PD is 2P then all is OK. -IF the PD is 4P then each 2P will receive XX watts max. -PD is responsible for current sharing in order to utilize the max power and not cause an overload condition on any 2P. -PSE would be required to turn on power on all 4P within TBD time (1ms max?) only after detection and classification ended successfully. -If an outlet is split to two separate PDs then they will be powered after PSE gets valid detection and classification data on each pair. This allows flexibility in application and infrastructure utilization as long as there is no hazard to equipment or users and there are no potential interoperability issues. 8. Classification is mandatory in AT-PD and AT-PSE. 9. Class policing will remain optional. 10. Classification method will support midspan and endpoint PSEs. 11. 25K signature resistance will not be changed. Issues the group felt must be discussed further: 1. What should the low end of the power range be, 1W, 2W, or other? 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? 8. Should classification be mandatory in PSE? I think the answer is yes. 9. Should classification be mandatory in PD? 10. In a split cable installation using a 4P AT PSE, is it expected that both PDs should receive power? Subjects for Future Discussions Power supply utilization PRESENTATIONS Yair provided a Preliminary Comparison Table. Classification methods review - Comparision table.doc Yair referenced several previous works http://grouper.ieee.org/groups/802/3/poep_study/public/jul05/ Classification Resolution Requirements Analysis darshan_2_0705.pdf How power Management Reduces System Costs darshan_2_0305.pdf Classification Resolution Analysis darshan_3_0705.pdf Steve Robbins presented “Extended Detection Protocol for 4p PSE” 4P_Detection_B_W.pdf (65k) Christian Beia Backwards compatible enhanced classification scheme __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com
3259433781-Summary 2-23-06.doc