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SNMP Configuration Summary
8-2 SNMP Configuration
SNMPv1 and SNMPv2c
ThecomponentsofSNMPv1andSNMPv2cnetworkmanagementfallintothreecategories:
•Manageddevices(suchasaswitch).
•SNMPagentsandMIBs,includingSNMPtraps,communitystrings,andRemoteMonitoring
(RMON)MIBs,whichrunonmanageddevices.
•SNMPnetworkmanagementapplications,suchastheEnterasysNetSightapplication,which
communicatewithagents
togetstatisticsandalertsfromthemanageddevices.
SNMPv3
SNMPv3isaninteroperablestandards‐basedprotocolthatprovidessecureaccesstodevicesby
authenticatingandencryptingframesoverthenetwork.Theadvancedsecurityfeaturesprovided
inSNMPv3areasfollows:
– Messageintegrity—Collects datasecurel ywithoutbeing tamperedwithorcorrupted.
– Authentication—Determinesthemessageisfroma
validsource.
–Encryption—Scramblesthecontentsofaframetopreventitfrombeingseenbyan
unauthorizedsource.
UnlikeSNMPv1andSNMPv2c,inSNMPv3,theconceptofSNMPagentsandSNMPmanagersno
longerapply.TheseconceptshavebeencombinedintoanSNMPentity.AnSNMPenti tyconsists
ofanSNMPengineandSNMPapplications.AnSNMPengineconsistsofthefollowingfour
components:
•Dispatcher—Thiscomponentsendsandreceivesmessages.
•Messageprocessingsubsystem—ThiscomponentacceptsoutgoingPDUsfromthe
dispatcherandpreparesthemfortransmissionbywrappingtheminamessageheaderand
returningthem
tothedispatcher.Themessageprocessingsubsystemalsoacceptsincoming
messagesfromthedispatcher,processeseachmessageheader,andreturnstheenclosedPDU
tothedispatcher.
•Securitysubsystem—Thiscomponentauthenticatesandencryptsmessages.
• Accesscontrolsubsystem—Thiscomponentdetermineswhichusersandwhichoperations
areallowedaccessto
managedobjects.
About SNMP Security Models and Levels
AnSNMPsecuritymodelisanauthenticationstrategythatissetupforauserandthegroupin
whichtheuserresides.Asecuritylevelisthepermittedlevelofsecuritywithinasecuritymodel.
ThethreelevelsofSNMPsecurityare:Noauthenticationrequired(NoAuthNoPriv);
authenticationrequired(AuthNoPriv);and
privacy(authPriv).Acombinationofasecuritymodel
andasecurityleveldetermineswhichsecuritymechanismisemployedwhenhandlinganSNMP
frame.Table 8‐1identifiesthelevelsofSNMPsecurityavailableonSecureStackC3devicesand
authenticationrequiredwithineachmodel.