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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

Enterasys SecureStack C3G124-24P User Manual

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