D-Link DWS-4026 [153/741] Sflow sampler configuration

ConfiguringsFlow

D-Link UnifiedWiredandWirelessAccessSystem

November2011 Page153

D‐LinkUWSUserManual

sFlowSamplerConfiguration

ThesFlowAgentcollectsastatisticalpack et ‐basedsamplingoftheswitchedflowsandsendsthemtothe

configuredreceivers.Adatasourceconfiguredtocollectflowsamplesiscalledasampler.

PacketFlowSampling

ThePacketFlowSamplingmechanismcarriedoutbyeachsFlowinstanceensuresthatanypacketobserve dat

aDataSourcehasanequalchanceofbeingsampled,irrespectiveofthePacketFlow(s)towhichitbelongs.

PacketFlowSamplingisaccomplishedasfollows:

•Whenapacketarrivesonaninterface,theNetworkDe

vicemakesafilteringdecisiontodetermine

whetherthepacketshouldbedropped.

•Ifthepacketisnotfiltered(dropped),adestinationinterfaceisassignedbytheswitching/routingfunction.

•Atthispoint,adecisionismadeonwhetherornottosamplethepacket.Themechanisminvolvesa

counterthatisdecrementedwitheachpacket.Whenthecounterreacheszero,asampleistak en.Whena

sampleistaken,thecounterthatindicateshowmanypacketstoskipbeforetakingthene

xtsampleis

reset.Thevalueofthecounteris settoarandomintegerwherethesequenceofrandomintegersused

overtimeistheSamplingRate.

ToaccessthesFlowSamplerConfigurationpage,clickLAN>Administration>sFlow>SamplerConfiguration

inthenavigationtree.

Figure78:sFlowSamplerConf

iguration

Table68:sFlowSamplerConfiguration

Field Description

SamplerDatasource ThesFlowDatasourceforthissFlowsampler.ThisAgentwillsupportPh ysicalports

only.

ReceiverIndex ThesFlowReceiverforthissFlowsampler.Ifsettozero,nopacketswillbe

sampled.Onlyactivereceiverscanbeset.Ifareceiverexpires,thenallsamplers

associatedwiththereceiverwillalsoex

pire.Theallowedrangeis1to8.

SamplingRate Thestatisticalsamplingrateforpacketsamplingfromthissource.Asamplingrate

ofone(1)countsallpackets.Asamplingrateofzero(0)disablessampling.The

allowedrangeis1024to65536.

MaximumHeaderSize Themaximumnumberofbyt

esthatshouldbecopiedfromasampledpacket.The

allowedrangeis20to256.