Enabling/Disabling GVRP (GARP VLAN Registration Protocol)
10-20 802.1Q VLAN Configuration
Enabling/Disabling GVRP (GARP VLAN Registration Protocol)
About GARP VLAN Registration Protocol (GVRP)
Thefollowingsectionsdescribethedeviceoperationwhenitsportsareoperatingunderthe
GenericAttributeRegistrationProtocol(GARP)appl ication–GARPVLANRegistrationProtocol
(GVRP).
Overview
ThepurposeofGVRPistodynamicallycreateVLANsacrossaswitchednetwork.WhenaVLAN
isdeclared,theinformationistransmittedoutGVRPconfiguredportsonthedeviceinaGARP
formattedframeusingtheGVRPmulticastMACaddress.Aswitchthatreceivesthisframe,
examinestheframe,andextracts
theVLANIDs.GVRPthencreatestheVLANsandaddsthe
receivingporttoitstaggedmemberlistfortheextractedVLANID(s).Theinformationisthen
transmittedouttheotherGVRPconfiguredportsofthedevice.Figure 10‐1showsanexampleof
howVLANbluefromendstation
Awouldbepropagatedacrossaswitchnetwork.
How It Works
InFigure 10‐1onpage 10‐21,Switch4,port1isregisteredasbeingamemberofVLANBlueand
thendeclaresthisfactoutallitsports(2and3)toSwitch1andSwitch 2.Thesetwodevices
registerthisintheportegresslistsoftheports(Switch1,
port1andSwitch2,port1)thatreceived
theframeswiththeinformation.Switch2,whichisconnectedtoSwitch3andSwitch5declares
thesameinformationtothosetwodevicesandtheportegresslistofeachportisupdatedwiththe
newinformation,accordingly.
ConfiguringaVLAN
onan802.1Qswitch createsastaticVLANentry.Theentrywillalways
remainregisteredandwillnottimeout.However,dynamicentrieswilltime‐outand their
registrationswillberemovedfromthememberlistiftheendstationAisremoved.Thisensures
that,ifswitchesaredisconnected
orifendstationsareremoved,theregisteredinformation
remainsaccurate.
TheendresultisthattheportegresslistofaportisupdatedwithinformationaboutVLANsthat
resideonthatport,eveniftheactualstationontheVLANisseveralhopsaway.