Chapter 17 Power over Ethernet History of POE PoE Devices Planning and Deployment of PoE

Exam Essentials Know the history of PoE. –Make sure you know the history of PoE, the original 802.3af amendment, and current references to IEEE Std , Clause 33. Know the different PoE devices and how they interoperate. –Make sure you know the different PoE devices and their roles in providing PoE. Make sure you understand how the following devices work: powered device (PD), power-sourcing equipment (PSE), endpoint PSE, and midspan PSE. Know the different device classes and the classification process. –Make sure you know the five device classes and how the classification process works to determine the class of a powered device. Know how much current each class of devices uses along with how much power the PSE generates for each class of devices.

History of PoE Power from the network –Telephones!! VoIP phones, cameras, APs –Using the non-data wires on ethernet cable Reduce the need for power cables

NonStandard PoE Early proprietary solutions Different voltages DON’T MIX!!!

Standard PoE 802.3af –Original standard Clause 33 –When af was incorporated into main document at –New standard (PoE+) –More power with ackward compatibility

PoE Devices Powered Device –Draw power-up to 57 volts –AP or phone

Power Sourcing Device PSE provides power to powered device –48 Volt (44 to 57) –Use DC detection signal –If PoE device found, power is supplied PSE provide more power just in case

Power Levels

Endpoint PSE Power and Ethernet from same device PoE capable switches, WLAN controllers

Mindspan PSE Pass though devices Add power to ethernet cable –Don’t need to replace current equipment

Pin Assignements

Planning and Deploying PoE Power Planning –How many devices will be powered –Must make a power budget Will device classify itself? Redundancy –What is the backup?

Exam Essentials Know the history of PoE. –Make sure you know the history of PoE, the original 802.3af amendment, and current references to IEEE Std , Clause 33. Know the different PoE devices and how they interoperate. –Make sure you know the different PoE devices and their roles in providing PoE. Make sure you understand how the following devices work: powered device (PD), power-sourcing equipment (PSE), endpoint PSE, and midspan PSE. Know the different device classes and the classification process. –Make sure you know the five device classes and how the classification process works to determine the class of a powered device. Know how much current each class of devices uses along with how much power the PSE generates for each class of devices.