Specifications

How Do I Implement PoE?
June 3, 2011 Page 3 of 14
• Automaticmode,inwhichavailablepowerisdistributedevenlytoPoE‐capablemodules
basedonPoEportcount.(Thisisthedefaultmode.)Anychangeinavailablepower,duetoa
changeinpowersupplystatusorredundancymodeortotheadditionorremovalofmodules,
willtriggeran
automaticredistributionofpower.
• Manualmode,inwhichthepowerbudgetforeachPoE‐capablemoduleismanually
configured,usingeitherCLIcommandsortheMIBs.Thesumofthewattageconfiguredfor
eachmodulecannotexceedthetotalpoweravailableontheswitchforPoE.
Thepowerbudgetforeach
PoE‐capablemodulecanbeconfiguredmanuallyontheG‐Series
withthecommandsetinlinepowerassignandontheS‐Series,N‐Series,andK‐Serieswith
thecommandsetinlinepowerassigned .
Theconfiguredwattageassignmentsareusedtocalculateeachslot’spercentageoftotal
availablepowe r.Ifthe
totalavailablePoEpowerisreduced,aredistributionofavailable
powerwilloccur,applyingthecalculatedpercentages.
When Manual Mode is Configured
Whenmanualdistributionmodeisconfigured,ifaPoEmoduleisaddedtotheswitch,thePoE
powerbudgetforexistingmoduleswillnotberecalculated.Thenewmodulewillhaveapower
budgetofzerountilitismanuallyprovisioned.Sincethesumofthemanuallyprovisioned
wattagescannotexceed
thetotalsystempoweravailable,itmaybenecessarytoadjustexisting
budgetstofreeuppowerforthenewmodule.
WhenaPoEmoduleisremovedfromaswitchconfiguredwithmanualpowerdistributionmode,
thePoEbudgetforeachmodulewillnotberecalculated,basedontheassumptionthat
themodule
removedwillbereplacedwithanewmodulethatshouldreceivethesameamountofPoEpower.
Asnotedabove,ifthetotalavailablePoEpowerisreduced,thepowerwillautomaticallybe
redistributedbasedonapplyingthecalculatedpercentages.IfanadditionalPoEsupplyis
installed,thereis
noimpactontheassignedPoEsincespecificwattageshavebeenassignedto
eachmodule.Onlythe“TotalPowerDetected”valuewillchange.TheextraPoEpower,however,
isavailableforfurtherredistributionmanually.
Management of PoE Power to PDs
ForeachPoE‐capablemoduleorswitch(fortheproductslistedabove),youcanconfigurehowits
PoEcontrollermakespoweravailabletoattachedpowereddevices(PDs).Onapermodulebasis,
youcanconfigure:
• Real‐timemode,inwhichthePoEcontrollercalculatesthepowerneededbyaPDbased
on
theactualpowerconsumptionoftheattacheddevices.
• Classmode,inwhichthePoEcontrollermanagespowerbasedontheIEEE802.3af/.3at
definitionoftheclasslimitsadvertisedbytheattacheddevices,withtheexceptionthatfor
class0andclass4devices,actualpowerconsumptionwillalwaysbe
used.Inthismode,the
maximumamountofpowerrequiredbyadeviceintheadvertisedclassisreservedforthe
port,regardlessoftheactualamountofpowerbeingusedbythedevice.
PowermanagementtoPDsisconfiguredwiththecommandsetinlinepowermanagement.PoE
classesaredefinedin
Table 1onpage 2.
Note: This feature is available only on B5, C5, G-Series, N-Series, S-Series, and K-Series
products.