Chapter 8: Power Over Ethernet Overview
194
GE-DS-242-PoE Managed Ethernet Switch User Manual
PoE System Architecture
The specification of PoE typically requires two devices: the Powered Source
Equipment (PSE) and the Powered Device (PD). The PSE is either an End-Span or a Mid-
Span, while the PD is a PoE-enabled terminal, such as IP Phones, Wireless LAN, etc.
Power can be delivered over data pairs or spare pairs of standard CAT-5 cabling.
How Power is Transferred Through the Cable
A standard CAT5 Ethernet cable has four twisted pairs, but only two of these are used
for 10BASE-T and 100BASE-T. The specification allows two options for using these
cables for power, shown in Figure 8-1 and Figure 8-2:
The spare pairs are used. Figure 8-1 shows the pair on pins 4 and 5 connected
together and forming the positive supply, and the pair on pins 7 and 8 connected and
forming the negative supply. (In fact, a late change to the spec allows either polarity
to be used).
Figure 8-1: Power Supplied over the Spare Pins
Summary of Contents for GE-DS-242-POE
Page 1: ...GE Security P N 1069174 REV 1 0 ISS 22FEB10 GE DS 242 PoE Managed Ethernet Switch User Manual ...
Page 14: ...Chapter 1 Introduction 10 GE DS 242 PoE Managed Ethernet Switch User Manual ...
Page 124: ...Chapter 4 Web Based Management 120 GE DS 242 PoE Managed Ethernet Switch User Manual ...
Page 130: ...Chapter 5 Console Management 126 GE DS 242 PoE Managed Ethernet Switch User Manual ...
Page 204: ...Chapter 8 Power Over Ethernet Overview 200 GE DS 242 PoE Managed Ethernet Switch User Manual ...
Page 210: ......