Specifications

About QoS
RoamAbout Mobility System Software Configuration Guide 12-13
U-APSD Support
WMMclients thatusepowersavemodecanmoreefficientlyrequestbufferedunicastpacketsfrom
APradiosbyusingU‐APSD.
WhenU‐APSDsupportisenabledinMSS,aclientcanretrievebufferedunicastpacketsfora
trafficpriorityenabledforU‐APSDbysendingaQoSdataorQoS‐Null
frameforthatpriority.U‐
APSDcanbeenabledforindividualtrafficpriorities,forindividualclients,basedontheclient’s 
request.AclientenablesU‐APSDforatrafficprioritybyindicatingthispreferencewhen
(re)associatingwiththeAPradio.
AclientcanbutisnotrequiredtorequestU‐
APSDforallfourtrafficpriorities.TheAPradiostill
bufferspacketsforalltrafficprioritieseveniftheclientdoesnotrequestU‐APSDforthem.
However,toretrievebufferedpacketsforprioritiesthatarenotusingU‐APSD,aclientmustsend
aseparatePSpollforeachbufferedpacket.

U‐APSDissupportedonlyforQoSmodeWMM.
(ToenableU‐APSDsupport,see“EnablingU‐APSDSupport”onpage 12‐15.)
Call Admission Control
CallAdmissionControl(CAC)isanoptionalfeaturethathelpsensurethathigh‐priorityclients
haveadequatebandwidth,bylimitingthenumberofactivesessionsAPradioscanhaveforan
SSID.Forexample,youcanlimitthenumberofactivesessionsonaVoIPSSIDtoensurethateach
call
receivesthebandwidthrequiredforqualityvoiceservice.
YoucanuseCACwitheitherQoSmode(WMMorSVP).
CACisdisabledbydefault.Youcanenablesession‐basedCAConaservice‐profilebasis.When
enabled,CAClimitsthenumberofactivesessionsaradiocanhaveto14by
default.Youcan
changethemaximumnumberofsessionstoavaluefrom0to100.
ToconfigureCAC,see“ConfiguringCallAdmissionControl”onpage 12‐15.
Broadcast Control
YoualsocanenhancebandwidthavailabilityonanSSIDbyenablingthefollowingbroadcast
controlfeatures:
•ProxyARP—TheswitchrespondsonbehalfofwirelessclientstoARPrequestsfortheirIP
addresses.
•DHCPRestrict—TheswitchcapturesanddoesnotforwardanytrafficexceptDHCPtrafficfor
awirelessclientwhois
stillbeingauthenticatedandauthorized.
•NoBroadcast—Sendsunicaststoclients forARPrequestsandDHCPOffersandAcksinstead
offorwardingthemasmulticasts.
Allthesebroadcastcontroloptionsaredisabledbydefault.
Toenablebroadcastcontrolfeatures,see“EnablingBroadcastControl”onpage 12‐17.
Note: CAC is configured on a service profile basis and limits association to radios only for the
service profile’s SSID. Association to the radios by clients on other SSIDs is not limited. To ensure
voice quality, do not map other service profiles to the radio profile you plan to use for voice traffic.