RADWIN2000CPlusUserManual Release3.5.70 13‐2
VLANTagging Chapter13
VLANTagging
VLANtaggingenablesmultiplebridgednetworkstotransparently sharethesamephysical
networklinkwithoutleakageofinformationbetweennetworks:
IEEE802.1Qisusedastheencapsulationprot ocoltoimplementthismechanismover
Ethernetnetworks.
QinQ(DoubleTagging)forServiceProviders
QinQisusefulforServiceProviders,allowingthemtouseVLANsinternallyintheir“transport
network”whilemixingEthernettrafficfromclientsthatarealreadyVLAN‐tagged.
Theoutertag(representingtheProviderVLAN)comesfirst,followedbytheinnertag.InQinQ
theEtherT ype=0x9100.VLANtagsmaybestackedthreeormoredeep.
Whenusingthistypeof“ProviderTagging ”youshouldkeepthefollowinginmind:
• UnderProviderTagging,thesystemdouble‐tagsegressframestowardstheProvider’s
network.Thesystemadds atagwithaVLANIDandEtherType=0x9100toallframes,as
configuredbytheserviceprovider(ProviderVLANID).
• Thesystemalwaysaddstoeachframe,tagswithVLANIDandEtherT ype=0x9100.
Therefore,
• Foraframewithoutatag–thesystemwilladdatagwithVLANIDandEtherType=
0x9100sotheframewillhaveonetag
• ForaframewithaVLANtag–thesystemwi ll addatagwithVLANIDandEtherT ype
=0x9100sotheframewillbedouble‐tagged
ForaframewithaVLANtagandaprovidertag–thesystemwilladdatagwithVLANIDand
EtherT ype=0x9100sotheframewillbetriple‐taggedandsoon.
Attheegressside,theHSUremovestheQinQtagwithEtherType=0x9100nomatterwhat
thevalueofitsVLANID.
VLANUntagging
VLANUntaggingmeanstheremovalofaVLANoraProvidertag.
PortFunctionality
InaRADWIN2000CPluslink,allVLANactivityisconfiguredandsupportedfromtheHSUs.
Tothisend,VLANfunctionalityissupportedattheMNGportoftheHSU.
TheHSUMNGportcanbeconfiguredtohandleEthernetframesattheingressdirection
(whereframesentertheHSU)andattheegressdirection(whereframesexittheHSU).