PoE/PoE+ Planning and Implementation Guide 2011-09

Gloss-1
Glossary
Glossary
active PoE port - PoE-enabled port connected to a PD and currently
delivering power.
priority class - Refers to the type of power prioritization where the switch
uses Low (the default), High, and Critical priority assignments to determine
which groups of ports will receive power. Note that power priority rules apply
only if PoE provisioning on the switch becomes oversubscribed.
EPS - External Power Supply
MPS - Maintenance Power Signature; the signal a PD sends to the switch to
indicate that the PD is connected and requires power.
Oversubscribed - The state where there are more PDs requesting PoE power
than can be accommodated.
PD - Powered Device. This is an IEEE 802.3af-compliant device that receives
its power through a direct connection to a 10/100Base-TX PoE RJ-45 port on
the switch. Examples of PDs include Voice-over-IP (VoIP) telephones, wire-
less access points, and remote video cameras.
port-number priority - Refers to the type of power prioritization where,
within a priority class, the switch assigns the highest priority to the lowest-
numbered port, the second-highest priority to the second lowest-numbered
port, and so-on. Note that power priority rules apply only if PoE provisioning
on the switch becomes oversubscribed.
PoE - Power-Over-Ethernet; the method by which PDs receive power from a
PoE module (operates according to the IEEE 802.3af standard). Some pre-
standard PoE devices are also supported.
PoE+ - Power-over-Ethernet Plus; the method by which PDs receive power
according to the 802.3at standard. It is backward compatible with devices
using the 803.3af standard.
PSE - Power-Sourcing Equipment. A PSE, such as the Series 3500yl Switches,
or the modules in a E5400zl chassis, provides power to IEEE 802.3af or
802.3at- compliant PDs directly connected to 10/100/1000Base-T PoE RJ-45
ports on the switch. The Series 3500yl Switches and the Switch zl PoE Modules
are endpoint PSEs.
RPS - Redundant Power Supply