This MIB is intended for devices powered by 
external power sources, in particular Power 
Over Ethernet (PoE or formerly called inline 
power), to provide power usage configuration 
and information for NMS.  For example, PoE 
supplies DC power over standard Category 5 
unshielded twisted-pair (UTP) cable.  Instead 
of requiring wall power, powered devices such 
as IP telephones can utilize power provided
from power source equipments.  By using Cisco
Discovery Protocol (CDP),  powered devices 
can negotiated with power source equipment to
obtain optimum power supply. 
  
 
                  GLOSSARY

Midspan Injector
    The midspan PSE sends out a signal tone down
    one of the unused pairs of the standard 
    Category 5 cable and detects tone on the 
    other unused pair when the PD loops this tone
    back to it through a loopback transformer.  
    Once the midspan PSE detects this tone, it 
    begins to provide power down the cable using 
    the unused pairs.  The midspan PSE provide no 
    physical layer capability. 

Powered Device ( PD )
    These are devices powered by external electrical
    power sources.  They are, for example, IP 
    telephones and wireless Access Points or bridges. 

Power Source Equipment ( PSE )
    These are devices supplying electrical power to  
    other equipments.  They are, for example, inline 
    power switches and power patch panels.