Specifications

Enabling Prioritization for Legacy Voice over IP
RoamAbout Mobility System Software Configuration Guide 15-23
Enabling Prioritization for Legacy Voice over IP
MSSsupportsWi‐FiMultimedia(WMM).WMMsupportisenabledbydefaultandis
automaticallyusedforprioritytrafficbetweenWMM‐capabledevices.
MSSalsocanprovideprioritizationfornon‐WMMVoIPdevices.However,toprovidepriority
servicetonon‐WMMVoIPtraffic,youmustconfigurestaticCoSorconfigurean
ACLtosetthe
CoSforthetraffic.TheAPmapstheCoSvalueassignedbystaticCoSortheACLtoaforwarding
queue.TheexamplesinthissectionshowhowtoconfigureCoSusingACLs.TousestaticCoS
instead,see“ConfiguringStaticCoS”onpage 12‐16.
General Guidelines
EnterasysNetworksrecommendsthatyoufollowtheseguidelinesforanywirelessVoIP
implementation:
•Ensureend‐to‐endpriorityforwardingbymakingsurenoneofthedevicesthatwillforward
voicetrafficresetsIPToSorDiffservvaluesto0.Somedevices,suchassometypesofLayer2 
switcheswithbasic
Layer3awareness,resettheIPToSorDiffservvalueofuntrustedpackets
to0.
•MSSusesIPToSvaluestoprioritizevoicetraffic.Forexample,whenanAPreceivestraffic
fromitsRoamAboutSwitch,theAPclassifiesthetrafficbasedontheIPToSvalueintheIP
headerof
thetunnelthatiscarryingthetraffic.Bydefault,theRoamAboutSwitchmarks
egresstrafficforpriorityforwardingonlyifWMMisenabledandonlyiftheingresstraffic
wasmarkedforpriorityforwarding.Ifanotherforwardingdeviceinthenetworkresetsa
voicepacket’sprioritybychangingtheIP
ToSorDiffservvalueto0,theRoamAboutSwitch
doesnotreclassifythepacket,andthepacketdoesnotreceivepriorityforwardingontheAP.
•ForWMM‐capabledevices,leaveWMMenabled.
•ForSVPdevices,changetheQoSmodetosvp.YoualsoneedtodisableIGMPsnooping,and
configurean
ACLthatmarksegresstrafficfromthevoiceVLANwithCoSvalue7.(See
“EnablingSVPOptimizationforSpectraLinkPhones”onpage 15‐24forcomplete
configurationguidelines.)
For other types of non-WMM devices, you do not need to change the QoS mode, but you must
configure an ACL to mark the traffic’s CoS value. This section shows examples for
configuring VoIP for devices that use TeleSym, and for Avaya devices.

Table 15‐5showshowWMMpriorityinformationismappedacrossthenetwork.WhenWMMis
enabledinMSS,RoamAboutSwitchesandAPsperformthesemappings automatically.
Table 15-5 WMM Priority Mappings
Service
Type
IP Precedence IP ToS DSCP 802.1p CoS
AP Forwarding
Queue
0 0 0 0 0 0 Background
3 3 0x60 24 3 3
1 1 0x20 8 1 1 Best Effort
2 2 0x40 16 2 2
4 4 0x80 32 4 4 Video
5 5 0xa0 40 5 5