Specifications

Configuring NetFlow on the Enterasys S-Series, N-Series, and K-Series Modules
May 18, 2011 Page 8 of 21
WhentransmittingNetFlowVersion5reports,themoduleuses“NetFlowinterface”indexes.
NormallythesewouldbeactualMIB‐2ifIndexvalues,buttheVersion5recordformatlimitsthe
valuesto2bytes,whichisnotsufficienttohold4‐byteifIndexes.NetFlowcollectorapplications
thatusethein/outinterfaceindexes
togatherSNMPdataabouttheinterface(suchasifName)
musttranslatetheinterfaceindexesusingtheEnterasysMIBetsysNetFlowMIB
(1.3.1.6.1.4.1.5624.1.2.61).
WithNetFlowversion9,packetsaremadeupoftemplatescontainingasetofdatarecords.
Templatesaresentaftertheperiodconfiguredforthetemplatetimeoutwhena
moduleor
collectionserverfirstbootsup.Datarecordsforversion9cannotbeprocessedwithoutan
up‐to‐datetemplate.Collectorsignoreincomingpacketsuntilatemplate arrives.Templatesare
refreshedperiodicallybaseduponapacketrefreshrateandtimeoutperiod.Settingthe
appropriaterefreshrateforyoursystemmust
bedetermined,sincethedefaultsettingsofa
20‐packetrefreshrateanda30‐minutetimeoutmaynotbeoptimalforyourenvironment.See
ConfiguringNetFlowExportVersionRefreshonpage 8.
NetFlowVersion9recordsgeneratedbymodulesusetrueMIB‐2ifIndexvaluessincethetemplate
mechanismpermitstransmissi on
of4‐byteifIndexes.Version9alsouses8‐bytepacketandbyte
counters,sotheyarelesslikelytorollover.Checkwithyourcollectorprovidertodetermineif
theyprovidethenecessarysupport.
ThecurrentEnterasysVersion9implementation:
•Doesnotsupportaggregationcaches.
•Provides15IPv4and15IPv6
predefinedtemplates.TheS‐Seriesfirmwareautomatically
selectstheappropriatetemplateforeachflowdependingonwhethertheflowisroutedor
switched,whetheritisaTCP/UDPpacketornot,andcontainsfieldsappropriate tothedata
recordssupportedinthetemplate.SeeTable 6onpage 2‐16fora
listingoftheheaderfields
supportedbytheNetFlowVersion9templates.SeeTable 7onpage 2‐17foralistingofthe
basedatarecordfieldssupportedbyallNetFlowVersion9templates.SeeTable 8onpage 2‐17
foralistingoftheadditionaltemplatespecificdatarecordfieldssupportedby
theNetFlow
Version9templates.SeeTable 9onpage 2‐18foralistingofIPv4andIPv6Version9NetFlow
templatesbytemplateIDanddescription.
Usethesetnetflowexport‐version{5|9}commandtosettheNetFlowexportversion.
Usetheclearnetflowexport‐versioncommandtoresetthe
exportversiontothedefaultvalueof
Version5.
Configuring NetFlow Export Version Refresh
Version9templaterecordshavealimitedlifetimeandmustbeperiodicallyrefreshed.Templates
areretransmittedwheneither
•thepacketrefreshrateisreached,or
•thetemplatetimeoutisreached.
Templaterefreshbasedonthetimeoutperiodisperformedoneverymodule.Sinceeachmodule
handlesitsownpackettransmissions,templaterefresh
basedonnumberofexportpacketssentis
managedbyeachmoduleindependently.
TherefreshratedefinesthemaximumdelayaneworrestartedNetFlowcollectorwould
experience,beforeitlearnstheformatofthedatarecordsbeingforwarded(fromthetemplate
referencedbythedatarecords).RefreshratesaffectNetFlow
collectorsduringtheirstartup.
Collectorsmustignoreincomingdataflowreportsuntiltherequiredtemplateisreceived.