# PoE ## 規格 ### IEEE - 802.3af - 802.3at - 802.3bt ## Keywords - PSE: Power sourcing equipment - PD: Powered device ## IEEE 802.3at-2009 (as known as oE+, PoEP (?)) - cat 5e or more required. - class0(Type-1): Min PSE Power 15.4W, Max PD Power 12.95W (0.44–12.95 W at the PD; default classification) - class1(Type-1): Min PSE Power 4W, Max PD Power 3.84W (0.44–3.84 W at the PD) - class2(Type-1): Min PSE Power 7W, Max PD Power 6.49W (3.84–6.49 W at the PD) - class3(Type-1): Min PSE Power 15.4W, Max PD Power 12.95W - class4(Type-2): Min PSE Power 30.0W, Max PD Power 25.5W (12.95 W to 25.50 W at the PD). - back compatible with IEEE802.3af-2003 - Type1: Low power, Type2: High power - Cabling: CAT5E required - Voltage: PSE voltage from 44V to 57V (50V to 57V for Type-2 PSEs) - Current level: 600mA assuming cable temperature is 50C or lower - Polarity: End-Spans can use MDI or MDI-X (Positive or Negative Polarity) - Pulse transformer inductance: – End-Span PSE (Switch) & PDs: 120µH (allows usage of IEEE802.3af magnetics) – Mid-Span: 350µH, Midspan Alternative-A 10/100 installations require regulation - Power Feeding: 2-pairs and 4-pairs possible – Focus on 2-pairs Medium Power: PSE 30W output, PD 25.5W input – 4-pairs High Power should be based on 2x2-pairs: PSE 60W output, PD 51W input - Type1ではPDのL1 negotiation(Classification) だけで可能(ほかはOptional)だが,Type2ではPDのL1, L2 negotiation, およびPSEのL1 negotiationが必須. ## IEEE 802.3af - Cat 3 or more required. - IEEE 802.3af-2003的には - up to 15.4 W of DC power(minimum 44 VDC and 350 mA) to each device.Only 12.95 W is assured to be available at thepowered device (PD) as some power isdissipated in the cable. - 距離上限は100m. cat5eと一緒. - Approved: up to 12.95W (350mA) at 48V DC – Approved in 2003 for PDs up to 12.95W (350mA) at 48V DC – PoE requires handshake before applying power – Power Sourcing Equipment (PSE) transmits power over 2 pairs (4 of 8 wires) on Cat5/5e/6 cable – Connect/disconnect protocol for applying/disconnecting power - Detect device that needs power - Determines power needed - When to turn on power - Detect device disconnect (AC and DC disconnect) - When to remove power – Physical layer mechanism for PSE’s to characterize power demands of individual PD’s and thus manage power delivered per port. ## IEEE 802.3btも存在.これはより大電力.(ref: http://www.ieee802.org/802_tutorials/2017-07/PracticalPoEtutorial-7-10-17.pdf) - Type 3 - Covers Classes 1-6 - Classes 1-4 as before (i.e. IEEE 802.3-2015) - Class 5: 45W PSE, 40W PD - Class 6: 60W PSE, 51W PD - Minimum port voltage = 50V - Type 4 - Covers Classes 7 and 8 - Class 7: 75W PSE, 62W PD - Class 8: 90W PSE, 71.3W PD - Minimum port voltage = 52V ## related commans on cisco ios - show power inline - (config-if)# power inline {auto|static|never} [priority {critical|high|low}] - no lldp tlv-select power-management (Disables LLDP power negotiation(default: enabled)) - show power inline gigabitethernet 2/10 detail | begin LLDP ## references - ref: https://www.ieee.li/pdf/viewgraphs/introduction_to_poe_802.3af_802.3at.pdf - ref: https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst6500/ios/12-2SX/configuration/guide/book/power_over_ethernet.pdf