Enterasys SecureStack C3G124-24P

PoE (Power over Ethernet) Support
SecureStack C3 Installation Guide 1-5
PoE (Power over Ethernet) Support
Theswitchis802.3afcompliant,whichmeansitcanprovidepoweroverEthernetcable
connectionsfromits48,RJ45frontpanelconnectorstoPDsinthenetwork.
PoweroverEthernet(PoE)referstothe abilitytoprovide48Vdcpowertoapowered
deviceusingthesameEthernetcablingthatprovides
data.ModernEthernet
implementationsemploydifferentialsignalsovertwistedpaircables.Thisrequiresa
minimumoftwotwistedpairsforasinglephysicallink.Bothendsofthecableare
isolatedwithtransformersblockinganyDCorcommonmodevoltageonthesignalpair.
PoEexploitsthisfactbyusingtwo
twistedpairsasthetwoconductorstosupplyadirect
current.Onepaircarriesthepowersupplycurrentandtheotherpairprovidesapathfor
thereturncurrent.Whileseveralproprietarylegacyimplementations ofPoEhavebeen
deployedbyLANequipmentvendors,in2003theIEEEpublishedtheIEEE
802.3af‐2003
specification,whichispartofthe802.3suiteofstandards.
TheswitchisfullycompliantwiththeIEEE802.3afstandard.Itsupportsthestandard
resistor‐baseddetectionmethod,aswellasACdisconnectcapability.Theswitchisalso
capableofsupplying7.5wattsofpowertoallportssimultaneously.
Supportisalso
providedforthe802.3af‐definedmaximumof15.4watts.
EachPD(PoweredDevice)hasaPDC(PoweredDeviceClassification)thatistransmitted
totheswitchforpowermanagementpurposes.Table 1‐1onpage 1‐5liststhe
classificationsandtheassociatedpowerranges.
Table 1-1 Powered Device Classifications
Class Usage
PD Maximum Power Range
Usage
None Default 0.44 to 12.95 Watts
1 Optional 0.44 to 3.84 Watts
2 Optional 3.84 to 6.49 Watts
3 Optional 6.49 to 12.95 Watts
4 Not Allowed Reserved for Future Use