IEEE Adopts Proposal for Power over Ethernet
A proposal allowing midspans used in Power-over-Ethernet applications to put the power onto the data pair as required for Gigabit systems was made by Phihong USA, Freemont, Calif., to the IEEE802.3at task force at its most recent meeting on March 13—15, 2007 in Orlando, Fla.
“Numerous presentations to the IEEE have proven that this can be done without affecting the‘channel characteristics’ as specified in IEEE802.3 specifications,” said Keith Hopwood, vice president of marketing for Phihong USA.
Putting the power on the data pair is required for Gigabit systems as all wires are used to carry data. If 4-pair powering gets ratified then it will also be required to carry power on all the wires that carry data as well.
Phihong officials claim that their PoE midspans already do this, and that many customers have already implemented this, although it is technically outside the current IEEE802.3 specification. This approved resolution puts specific text into the new specification that makes it official.
The new standard is now in draft, and many items can still change. The standard is still a year away from ratification, but it is now possible to build hardware that meets these requirements with a high degree of confidence that they will be compliant to the standard.
When implemented as a standard, IEEE 802.3at (PoEPlus) will not only allow POE in Gigabit systems but will enable at least 30 watts of power and potentially up to 60 watts.