Design Guidelines for PoE Based Security Systems. Carlos Carle, P.E. SignaMax Systems, Inc.

Transcription

1 Design Guidelines for PoE Based Security Systems Carlos Carle, P.E. SignaMax Systems, Inc.

2 What is PoE? Power Over Ethernet or PoE Technology describes a system to safely transfer electrical power, along with data, to remote devices over standard data cables (Cat3, Cat5, Cat5e, Cat6) in an Ethernet network.

3 PoE Standard Development Technology first Developed by CISCO in 2000 to support IP Telephony deployments. The IEEE Standard was developed on 2003 (IEEE 802.3af). IEEE Revised Standard (IEEE 802.3at) released on Energy Efficient Ethernet Standard (EEE) was published in November 2010 (IEEE 802.3az).

4 PoE (Power Over Ethernet) There are 3 types of devices used in a PoE environment: PSE (Power Sourcing Equipment) Endspan PI (Power Injector) Midspan PD (Powered Device)

5 PoE Components Definition Power Sourcing Equipment (PSE) specially configured power supply designed to provide power safely to a valid PD. Powered Device (PD) End Device that accepts and uses power from the Ethernet cable for its operation. Midspan (PI) type of PSE and in simple terms is typically a pass through RJ45 box which adds PoE power, also known as a Power Injector.

6 TIA 568 A/B Wiring Diagrams

7 IEEE Ethernet Over Twisted Pair Cables 10 BASE T (Ethernet 10 MB/S) and 100 BASE TX (Fast Ethernet 100 MB/S) uses only two pairs for data transmission. Conductors 1 2, 3 6(Pairs2and3) 1000 BASE T (Gigabit Ethernet 1000 MB/S) uses all four pairs for data transmission.

8 10/100 BASE T Layout

9 1000 BASE TX Layout

10 PoE (PSE/PD) Block Diagram

11 PoE Midspan Block Diagram

12 PSE Equipment

13 PD Equipment

14 PoE Midspan Equipment

15 PoE System

16 PoE Security System

17 PoE (CISCO) CISCO original PoE delivers 15.4W of power from the Power Sourcing Equipment (PSE) to the Powered Devices (PD). Cisco PoE Switches uses the Cisco Discovery Protocol (CDS) to detect Cisco pre standard or IEEE 802.3af devices.

18 CISCO Discovery Protocol

19 IEEE 802.3af Standard (PoE) Requires CAT3 Cable or Higher. Standardized on 48 VDC as the Injected PoE voltage. Maximum Power Transmitted by PSE is 15.4W. Maximum Power Received by PD is 12.95W (2.45W Power wasted per Port).

20 IEEE 802.3af Standard (PoE) Only two pairs are needed for 10 BASE T(10 MB/S) and 100 BASE TX (100 MB/S) to transmit Power. Mode A PoweristransmittedontheData Conductors 1 2, 3 6(Pairs2and3). Mode B Power is transmitted on the unused Conductors 4 5, 7 8(Pairs1and4).

21 IEEE af (Mode A)

22 IEEE 802.3af (Mode B)

23 IEEE 802.3at Standard (PoE+) Known as PoE+, PoE Plus or Full Power PoE at defines two types of PSE: Type 1 (Over 2 Pairs) The PSE delivers a maximum of 15.4W over a voltage range of 44 to 57 VDC, using CAT3 cable or higher. Type 2 The PSE can supply 30.8W (Over 2 Pairs), or 60W (Over 4 Pairs) using a voltage range of 50 to 57 VDC, using CAT5 cable or higher.

24 IEEE af/at PSE Power Requirements

25 IEEE 802.3at Standard (PoE+) Powered Devices Has different classifications: Class 1 Power is limited to 3.84W (over two pairs). Very Low Power Device. Class 2 Power is limited to 6.49W (over two pairs). Low Power Device

26 IEEE 802.3at Standard (PoE+) Powered Devices Class 3 Power is limited to 13W (over two pairs). Mid Power Device. Class 4 Power is limited to 25.5W (over four pairs). High Power Device.

27 PoE Powering Schemes 802.3at There are four basic power schemes, each with two alternative power insertion method: Alternative A Power is supplied via center taps of the coupling transformers on data conductors 1 2, 3 6(Pairs2and3). Alternative B Power is transmitted over unused conductors 4 5, 7 8(Pairs1and4)

28 IEEE af/at PSE Power Requirements

29 IEEE af/at PSE Power Requirements

30 IEEE af/at Midspan Power Requirements

31 IEEE af/at Midspan Power Requirements

32 IEEE 802.3az Standard (EEE) Energy Efficient Ethernet (EEE) Released on Enhancements to Ethernet over Twisted Pair, that allows less power consumption during periods of low data activity. Projected Power savings of 45 to 80 percent (Switches, Routers, AP).

33 IEEE 802.3az Standard (EEE) Allows each port on a Switch (PSE) to power down into a standby or sleep mode when there s no activity. Switch detects cable length of each link and adjusts the power accordingly. Approximately 4.5W/port is wasted on a CAT5/CAT5e/CAT6/CAT6A cable after 100meters.

34 IEEE 802.3az Standard (EEE) Energy Efficient PoE (EEPoE) Increase efficiency by 94% transmitting over the same cable, powering IEEE802.3at compliant devices in synchronous four pairs. Projected Power savings of 45 to 80 percent (Switches, Routers, AP).

35 IEEE az (EEPoE) Example

36 Design Considerations for PoE 1) DO NOT assume your device is 802.3af compliant because it is listed as PoEcapable. 2) Because there is no requirement for PSEs toperformbothmodeaandmodeb, verify with the vendor documentation which mode their device utilizes. 3) Confirm specific model numbers and operation of the equipment required.

37 Design Considerations for PoE 4) Determine the Total Load of you PSE equipment by adding the power requirements of all the PD s plus a 25% buffer for future growth. 5) The application requires PoE+ or PoE devices?. This will determine if your switch will be PoE or Full PoE.

38 (PoE) Examples

39 (PoE) Examples

40 (PoE) Examples

41 (PoE) Examples

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43 THANKS. Carlos E. Carle, PE SignaMax Connectivity Systems