Specifications

About QoS
RoamAbout Mobility System Software Configuration Guide 12-11
Figure 12-5 WMM QoS in a RoamAbout Network
Figure 12‐5onpage 12‐11showsthefollowingprocess:
1. AusersendsvoicetrafficfromaWMMVoIPphone.ThephonemarkstheCoSfieldofthe
packetwithservicetype7,indicatingthatthepacketisforhighpriority(voice)traffic.
2. APAreceivesthevoicepacketandclassifiesthe
packetbymappingtheservicetypeinthe
802.11headertoan internalCoSvalue.Inthisexample,theservicetypeis7andmapsto
internalCoS7.
TheAPencapsulatesthedatainanIPtunnelpacket,andmarkstheDSCPvalueinthetunnel
headerbasedonthe
internalCoSvalue.Inthisexample,theAPmapsinternalCoS7toDSCP
56andmarkstheIPtunnelheader’sDSCPfieldwithvalue56.TheAPthensendsthepacketto
theRoamAboutSwitch.
3. RoamAboutSwitchAreceivesthepacketontheIPtunnelconnectingtheRoamAboutSwitch
toAPA.TheRoamAboutSwitchclassifiesthepacketbasedontheDSCPvalueintheIP
headerofthetunnelpacket(inthisexample,DSCP56),andmapsthisvaluetoaninternalCoS
value(inthisexample,7).
Note: In this example, the RoamAbout Switch interface with the AP is untagged, so the
RoamAbout Switch does not classify the packet based on its 802.1p value.
Layer 3
RAS B
Srvc Type = 7 Voice Data . . .
IP ToS = 0xe0 Voice Data. . .
802.1p = 7
IP ToS = 0xe0 Voice Data. . .
802.1p = 7
Voice
Video
Best Effort
Bgrnd
RAS A
AP A
AP B
4
1
2
3
5
6
Voice Data. . .
Tnl Hdr IP ToS = 0xe0
Voice Data. . .
Tnl Hdr IP ToS = 0xe0
Layer 3
Layer 3