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CrparMalcolmDavenport,derniremodificationlejuil.08,2015

AsteriskProject / / GeneralConfigurationInformation

IP Quality of Service

IntroductionAsterisksupportsdifferentQoSsettingsattheapplicationlevelforvariousprotocolsonbothsignalingandmedia.TheTypeofService(TOS)bytecanbesetonoutgoingIPpacketsforvariousprotocols.TheTOSbyteisusedbythenetworktoprovidesomelevelofQualityofService(QoS)evenifthenetworkiscongestedwithothertraffic.

AsteriskrunningonLinuxcanalsoset802.1pCoSmarksinVLANpacketsfortheVoIPprotocolsituses.Thisisusefulwhenworkinginaswitchedenvironment.InfactAsteriskonlysetpriorityforLinuxsocket.FormappingthispriorityandVLANCoSmarkyouneedtousethiscommand:

ThetablebelowshowsallVoIPchanneldriversandotherAsteriskmodulesthatsupportQoSsettingsfornetworktraffic.Italsoshowsthetype(s)oftrafficforwhicheachmodulecansupportsettingQoSsettings:

Signaling Audio Video Text

chan_sip + + + +

chan_skinny + + +

chan_mgcp + +

chan_unistm + +

chan_h323 +

chan_iax2 +

chan_pjsip + + +

DUNDI +(tossetting)

IAXProv +(tossetting)

IPTOSvalues

Theallowablevaluesforanyofthetosparametersare:CS0,CS1,CS2,CS3,CS4,CS5,CS6,CS7,AF11,AF12,AF13,AF21,AF22,AF23,AF31,AF32,AF33,AF41,AF42,AF43andef(expeditedforwarding),*

Thetosparametersalsotakenumericvalues.*

NotethatonaLinuxsystem,AsteriskmustbecompiledwithlibcapinordertousetheeftossettingifAsteriskisnotrunasroot.

Thelowdelay,throughput,reliability,mincost,andnonevalueshavebeenremovedincurrentreleases.

ToSdecimalequivalencetable:

name decimalvalue

cs0 0

cs1 32

af11 40

af12 48

af13 56

cs2 64

af21 72

af22 80

af23 88

vconfigset_egress_map[vlandevice][skbpriority][vlanqos]

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cs3 96

af31 104

af32 112

af33 120

cs4 128

af41 136

af42 144

af43 152

cs5 160

ef 184

cs6 192

cs7 224

802.1pCoSvalues

Because802.1puses3bitsoftheVLANheader,thisparametercantakeintegervaluesfrom0to7.

Recommendedvalues

Therecommendedvaluesshownbelowarealsoincludedinsampleconfigurationfiles:

tos cos

Signaling cs3 3

Audio ef 5

Video af41 4

Text af41 3

Other ef

IAX2

Iniax.conf,thereisa"tos"parameterthatsetstheglobaldefaultTOSforIAXpacketsgeneratedbychan_iax2.SinceIAXconnectionscombinesignalling,audio,andvideointooneUDPstream,itisnotpossibletosettheTOSseparatelyforthedifferenttypesoftraffic.

Iniaxprov.conf,thereisa"tos"parameterthattellstheIAXywhatTOStosetonpacketsitgenerates.Aswiththeparameteriniax.conf,IAXpacketsgeneratedbyanIAXycannothavedifferentTOSsettingsbaseduponthetypeofpacket.HoweverdifferentIAXydevicescanhavedifferentTOSsettings.

CHAN_SIP

Inchan_sip,therearefourparametersthatcontroltheTOSsettings:"tos_sip","tos_audio","tos_video"and"tos_text".tos_sipcontrolswhatTOSSIPcallsignalingpacketsaresetto.tos_audio,tos_videoandtos_textcontrolwhatTOSvaluesareusedforRTPaudio,video,andtextpackets,respectively.Therearefourparameterstocontrol802.1pCoS:"cos_sip","cos_audio","cos_video"and"cos_text".ThebehavioroftheseparametersisthesameasfortheSIPTOSsettingsdescribedabove.

CHAN_PJSIP

Inchan_pjsip,therearethreeparametersthatcontroltheTOSsettings:atosoptionforatype=transportthatcontrolstheTOSofSIPsignalingpackets,atos_audiooptionforatype=endpointthatcontrolstheTOSofRTPaudiopackets,andatos_videooptionforatype=endpointthatcontrolstheTOSofvideopackets.

Similarly,therearethereparametersthatcontrolthe802.1pCoSsettings:acosoptionforatype=transportthatcontrolsthe802.1pvalueforSIPsignalingpackets,acos_audiooptionforatype=endpointthatcontrolsthe802.1pvalueofRTPaudiopackets,and

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acos_videooptionforatype=endpointthatcontrolsthe802.1pvalueforvideopackets.

OtherRTPchannels

chan_mgcp,chan_h323,chan_skinnyandchan_unistimalsosupportTOSandCoSviasettingtosandcosparametersintheircorrespondingconfigurationfiles.Namingstyleandbehaviorarethesameasforchan_sip.

Reference

IEEE802.1QStandard:http://standards.ieee.org/getieee802/download/802.1Q1998.pdfRelatedprotocols:IEEE802.3,802.2,802.1D,802.1Q

RFC2474"DefinitionoftheDifferentiatedServicesField(DSfield)intheIPv4andIPv6Headers",Nichols,K.,etal,December1998.

IANAAssignments,DSCPregistryDifferentiatedServicesFieldCodepointshttp://www.iana.org/assignments/dscpregistryTogetthemostoutofsettingtheTOSonpacketsgeneratedbyAsterisk,youwillneedtoensurethatyournetworkhandlespacketswithaTOSproperly.ForCiscodevices,seethepreviouslymentioned"EnterpriseQoSSolutionReferenceNetworkDesignGuide".ForLinuxsystemsseethe"LinuxAdvancedRouting&TrafficControlHOWTO"athttp://www.lartc.org/.FormoreinformationonQualityofServiceforVoIPnetworksseethe"EnterpriseQoSSolutionReferenceNetworkDesignGuide"version3.3fromCiscoat:http://www.cisco.com/application/pdf/en/us/guest/netsol/ns432/c649/ccmigration_09186a008049b062.pdf

Changestoachan_pjsiptype=transportrequireanAsteriskrestarttobeaffected.TheyarenotaffectedbysimplyreloadingAsterisk.