DTE Power over MDI:
` Building Consensus
`Ralph Andersson
`TDK Semiconductor
`Daniel Dove
`Hewlett Packard
`Robert Muir
`Level One Communications
`
`May 24, 2000
`
`Ottawa IEEE 802.3af Interim
`Page 1 of 20
`
`CHRIMAR 2043
`
`
` Building Consensus
`Ralph Andersson
`TDK Semiconductor
`Daniel Dove
`Hewlett Packard
`Robert Muir
`Level One Communications
`
`May 24, 2000
`
`Ottawa IEEE 802.3af Interim
`Page 1 of 20
`
`CHRIMAR 2043
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`
`
`Objectives:
`
`•
`
`•
`
`I am not going to re-present all of the proposals for the application of
`power over the MDI
`I will focus on the proposals that have occurred within this group
`concerning which pairs to apply power over: the signal pairs or the
`IDLE pairs.
`• Benefits of each
`• Drawbacks of each
`• Consensus on the path where there is the greatest commonality
`•
`Is this possible?
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`Ottawa IEEE 802.3af Interim
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`Power over MDI:
`• Objectives to be considered from 11/99:
`(1) Economically provide power over a twisted- pair link segment to a single Ethernet
`device.
`• To be included:
`– 10BASE-T,
`– 100BASE-TX.
`• To be considered:
`– 1000BASE-T.
`(2) Select one power distribution technique for world wide use
`(3) Not cause damage and inter-operate with compliant RJ- 45 MDI Ethernet devices
`including:
`a. Switch- to- switch connections (both supplying power)
`b. Cross- over cables
`c. Common mode termination implementations
`d. Shorted conductors, pairs or loop- back plug Support current standard, 4- pair, horizontal
`cabling infrastructure for installed Cat 3 and Cat 5 cabling
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`Ottawa IEEE 802.3af Interim
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`Power over MDI:
`
`• Objectives to be considered from 11/99 (cont.):
`(4) Define a capability detection function that works with a powered and an un-
`powered device
`(6) Add appropriate management objects for power capability and status
`(7) Support current standard, 4- pair, horizontal cabling infrastructure for installed
`Cat 3 and Cat 5 cabling
`(8) Preserve the signal transmission and isolation characteristics of existing
`equipment and cabling
`(9) Maintain normal functionality of Link Integrity Test function in legacy and new
`devices
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`Ottawa IEEE 802.3af Interim
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`Power over MDI:
`
`• Motions to be considered:
`(1) Without specifying the two and only two pairs to be utilized for DTE power, DTE
`power shall utilize two pair powering where each wire in the pair is at the same nominal
`potential and the power supply potential is between the two pairs selected.
`Moved: Michael McCormack
`Second: Henry Hinrichs
`Yes: 23 Opposed: 4 Abstains: 3, Total attendance: 33, January 21, 2000
`(2) Regardless of the detection scheme adopted and the power feed scheme adopted, the
`power detection and the power feed shall operate on the same set of pairs.
`Moved: Michael McCormack
`Second: Dave Richkas
`Yes: 31 Opposed: 0 Abstaining: 1, Total Attendance 33, January 21, 2000
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`Ottawa IEEE 802.3af Interim
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`Power over MDI:
`
`• Motions to be considered:
`(3) In order to progress we accept that there are now two isolation requirements of 802.3,
`environment A and B per 802.3 section 27.5.3 et al, and that for the purposes of this
`committee we will treat as a priority for consideration environment B without
`precluding environment A.
`Moved: N. Stapleton Second: L. Miller
` Yes: 23 Opposed: 3 Abstaining: 9, March 7-8, 2000
`(4) Move to add a requirement that: The solution for DTE powering shall support mid-
`span insertion of the power source.
`Moved : A. Anderson Second: D. Dove
`Yes: 33 Opposed: 0 Abstaining: 1, March 7-8, 2000
`
`Ottawa IEEE 802.3af Interim
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`Power over MDI:
`
`• There are two camps:
`– Power over the signal pair.
`– Power over the idle pair.
`• A third camp violates Motion (1) and will not be discussed.
`– Power over both (TR41.4)
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`Ottawa IEEE 802.3af Interim
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`Power over MDI- Signal Camp:
`
`• How can mid-span insertion be supported with power applied over the
`signal pair?
`–
`Transformer inserted into signal path at mid-span
`• Return loss may be an issue; there is not much margin on a class D link to facilitate the
`insertion of new elements. Objectives (8) & (9)
`Insertion loss of the inserted element may be an issue. Objectives (8) & (9)
`•
`• Each transformer adds an additional pole into the forward transfer characteristics of the link.
`How many legacy transceivers will stop working? Objectives (8) & (9)
`– Use a different power pair for mid-span solutions
`
`Ottawa IEEE 802.3af Interim
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`Power over MDI- Signal Camp:
`Cisco’s Proposal
`• There has been quite a bit of confusion on the reflector over what
`Cisco’s proposal entails.
`• Sources for this portion of the presentation are:
`– Power over the DTE 1/00 Frazier et al, Cisco
`– Considerations for Mid-Span Power Insertion 3/00 Yousefi et al, Broadcom
`– DTE Power Detection Algorithm 3/00 Yousefi et al, Broadcom
`– Logical guess-work
`
`Ottawa IEEE 802.3af Interim
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`Power over MDI- Signal Camp:
`Cisco’s Proposal
`• Cisco’s switch based solution uses the 1236 pairs to supply common-
`mode power from the switch to a remote application requiring power.
`• Cisco’s mid-span solution uses the 4578 pairs to supply common-
`mode power for a mid-span power insertion.
`• 10BASE-T and 100BASE-TX applications are allowed to operate
`over a mid-span power insertion, 1000BASE-T is not.
`• 10BASE-T, 100BASE-TX, and 1000BASE-T applications are
`allowed to operate over a switch supplied power insertion.
`
`Ottawa IEEE 802.3af Interim
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`Power over MDI- Signal Camp:
`Cisco’s Switch-Based Proposal
`
`PHY DC/DC
`
`LPF
`
`End-Link
`
`CHRIMAR 2043
`
`48 Volt Return
`
`PHY
`
`SWITCH
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`Ottawa IEEE 802.3af Interim
`Page 11 of 20
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`
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`Power over MDI- Signal Camp:
`Cisco’s Mid-Span Proposal
`
`PHY DC/DC
`
`48 Volt Return
`
`Mid-Span
`
`LPF
`
`PHY
`
`SWITCH
`
`48 Volt Return
`
`End-Link
`
`Ottawa IEEE 802.3af Interim
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`Power over MDI- Signal Camp:
`Cisco’s Proposal
`
`• Advantages:
`– Return loss & insertion loss are not are not affected by the addition of the mid-span
`transformer element for 10BASE-T and 100BASE-TX applications.
`Follows Motion (2) and (4). Detection scheme and the power feed scheme operate on
`the same set of pairs. Mid-span is supported.
`– Will support 2 pair installed wiring for switched based power insertion.
`–
`Supports 1000BASE-T
`• Disadvantages:
`– Operates outside the intent of Motion (1). Power can be applied to more than two pairs.
`The letter of the law set forth by Motion (1), however, allows the multiple sources if
`only one is selected. This assumes a method for conveying discovery information
`between switch and mid-span. Assumes a foolproof power prioritization definition.
`Possible coupling between power supply noise events and transceiver performance for
`10BASE-T and 100BASE-TX PHYs.
`1000BASE-T not supported for mid-span insertions.
`–
`– Complex
`
`–
`
`–
`
`Ottawa IEEE 802.3af Interim
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`CHRIMAR 2043
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`Power over MDI- IDLE Pair Camp:
`• This proposal uses the 4578 pairs to supply common-mode power
`from the switch to a remote application requiring power.
`• This proposal uses the 4578 pairs to supply common-mode power for
`a mid-span power insertion.
`• 10BASE-T and 100BASE-TX applications are allowed to operate
`over a mid-span power insertion, 1000BASE-T is not.
`• 10BASE-T, 100BASE-TX, and 1000BASE-T applications are
`allowed to operate over a switch supplied power insertion.
`
`Ottawa IEEE 802.3af Interim
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`CHRIMAR 2043
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`
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`Power over MDI- IDLE Pair Camp:
`Switch Based Insertion
`
`PHY
`
`DC/DC
`
`PHY
`
`SWITCH
`
`48 Volt Return
`
`End-Link
`
`Ottawa IEEE 802.3af Interim
`Page 15 of 20
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`
`
`Power over MDI- IDLE Pair Camp:
`Mid-Span Insertion
`
`PHY
`
`DC/DC
`
`Mid-Span
`
`PHY
`
`SWITCH
`
`48 Volt Return
`
`48 Volt Return
`
`End-Link
`
`Ottawa IEEE 802.3af Interim
`Page 16 of 20
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`IDLE Pair Proposal:
`
`• Advantages:
`–
`Supports Motions (1), (2), and (4). Power is applied to two pair, discovery can be set
`up to operate on these pairs, and mid-span insertion of power can be supported.
`– Can support PHY based or power supply based discovery.
`– Return loss & insertion loss are not are not affected by the addition of the mid-span
`transformer element for 10BASE-T, 100BASE-TX, and 1000BASE-T applications.
`– No coupling between power supply noise events and transceiver performance for
`10BASE-T and 100BASE-TX PHYs.
`– Can support 1000BASE-T to the same extent that Cisco’s proposal can e.g. no
`1000BASE-T supported for mid-span insertions.
`• Disadvantages:
`– Won’t support 2 pair installed wiring. Objective (7) says this is O.K.
`–
`1000BASE-T not supported for mid-span insertions. Diligence is required if we want
`to design this to support 1000BASE-T for switched based power insertions.
`
`Ottawa IEEE 802.3af Interim
`Page 17 of 20
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`Consensus Objectives:
`• Select solution that supports Motions (1), (2), and (4)
`• Support of Motion (3) is understood and is common to all proposed
`solutions
`• Select solution that supports all Objectives
`• W.r.t. Objective (1) give strong consideration to support of
`1000BASE-T
`• K.I.S.S.
`
`Ottawa IEEE 802.3af Interim
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`Consensus Observations:
`• Signal 1236 pairs solution supports Motions (2), and (4). Motion (1)
`is debatable.
`IDLE 4578 pairs solution supports Motions (1), (2), and (4)
`•
`• Both Signal 1236 pairs and IDLE 4578 pairs solutions support all
`Objectives. Certain risk to 10BASE-T and 100BASE-TX solutions
`with Signal 1236 pairs solution.
`• Support of 1000BASE-T for switch based insertions only is common
`to both Signal 1236 pairs and IDLE 4578 pairs proposals
`
`Ottawa IEEE 802.3af Interim
`Page 19 of 20
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`CHRIMAR 2043
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`Consensus Conclusions:
`• Select IDLE 4578 pairs solution
`• Support 1000BASE-T support for switch based insertions only
`• Select discovery method that best supports Objective (6). Add
`appropriate management objects for power capability and status.
`
`Ottawa IEEE 802.3af Interim
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`CHRIMAR 2043
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`
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