Enabling/Disabling GVRP (GARP VLAN Registration Protocol)
SecureStack C2 Configuration Guide 8-19
Overview
ThepurposeofGVRPistodynamicallycreateVLANsacrossaswitchednetwork.WhenaVLAN
isdeclared,theinformationistransmittedoutGVRPconfiguredportsonthedeviceinaGARP
formattedframeusingtheGVRPmulticastMACaddress.Aswitchthatreceivesthisframe,
examinestheframe,andextracts
theVLANIDs.GVRPthencreatestheVLANsandaddsthe
receivingporttoitstaggedmemberlistfortheextractedVLANID(s).Theinformationisthen
transmittedouttheotherGVRPconfiguredportsofthedevice.Figure 8‐1showsanexampleof
howVLANbluefromendstation
Awouldbepropagatedacrossaswitchnetwork.
How It Works
InFigure 8‐1onpage 8‐19,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‐outandtheir
registrationswillberemovedfromthememberlistiftheendstationAisremoved.Thisensures
that,ifswitchesaredisconnected
orifendstationsareremoved,theregisteredinformation
remainsaccurate.
TheendresultisthattheportegresslistofaportisupdatedwithinformationaboutVLANsthat
resideonthatport,eveniftheactualstationonthe VLANisseveralhopsaway.
Figure 8-1 Example of VLAN Propagation via GVRP
End
Station A
Switch 4
Switch 5
= Port registered as a member of VLAN Blue
= Port declaring VLAN Blue
D
R
1
1
2
3
D
R
D
Switch 1
1
R
R
3
Switch 2
12
D
R
D
Switch 3
1
R
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