Enterasys RoamAbout RBT-4102 - Page 87

WDS and STP
RoamAbout RBT-4102 Wireless Access Point Configuration Guide 4-51
• WDSBridgeallowsyoutospecifyuptoeightWDSbridgelinks(MACaddresses)perradio
interfaceforeachunitinthewirelessbridgenetwork.Oneunitmustbeconfiguredasthe
“rootbridge”inthewirelessnetwork.Therootbridgeistheunitconnectedtothemaincoreof
thewiredLAN.Otherbridgesneedtospecifyone“Parent”linktotherootbridgeortoa
bridgeconnectedtotherootbridge.TheothersevenWDSlinksareavailableas“Child”links
tootherbridges.
– BridgeRoleallowsyoutoseteachradiointerfacetooperateinoneof
thefollowingmodes:
(Default:AP)
‐ AP(AccessPoint)tooperateasanaccesspointforwirelessclients,providing
connectivitytoawiredLAN.
‐ Bridgetooperateasabridgetootheraccesspoints.The“Parent”linktotheroot
bridgemustbeconfigured.Uptosevenother”Child”linksare
availabletoother
bridges.
‐ RootBridgetooperateastherootbridgeinthewirelessbridgenetwork.Uptoeight
”Child”linksareavailabletootherbridgesinthenetwork.
– BridgeParentisthephysicallayeraddressoftherootbridgeunitorthebridgeunit
connectedtotherootbridge.
(12hexadecimaldigitsintheform“xx‐xx‐xx‐xx‐xx‐xx”)
– BridgeChildisthephysicallayeraddressofotherbridgeunitsforwhichthisunitservesas
thebridgeparentortherootbridge.(12hexadecimaldigitsintheform“xx‐xx‐xx‐xx‐xx‐
xx”)
• SpanningTree
Protocolusesadistributedalgorithmtoselectabridgingdevice(STP‐compliant
switch,bridgeorrouter)thatservesastherootofthespanningtreenetwork.Itselectsaroot
portoneachbridgingdevice(exceptfortherootdevice)whichincursthelowestpathcost
whenforwardingapacketfrom
thatdevicetotherootdevice.Thenitselectsadesignated
bridgingdevicefromeachLANwhichincursthelowestpathcostwhenforwardingapacket
fromthatLANtotherootdevice.Allportsconnectedtodesignatedbridgingdevicesare
assignedasdesignatedports.Afterdeterminingthelowestcost
spanningtree,itenablesall
rootportsanddesignatedports,anddisablesallotherports.Networkpacketsaretherefore
onlyforwardedbetweenrootportsanddesignatedports,eliminatinganypossiblenetwork
loops.
Onceastablenetworktopologyhasbeenestablished,allbridgeslistenforHelloBPDUs
(BridgeProtocolDataUnits)transmitted
fromtherootbridge.IfabridgedoesnotgetaHello
BPDUafterapredefinedinterval(MaximumAge),thebridgeassumesthatthelinktotheroot
bridgeisdown.Thisbridgewilltheninitiatenegotiationswithotherbridgestoreconfigure
thenetworktoreestablishavalidnetworktopology.
– Bridge
enables/disablesSTPonthewirelessbridge.Default:Disabled
– BridgePriorityisusedinselectingtherootdevice,rootport,anddesignatedport.The
devicewiththehighestprioritybecomestheSTProotdevice.However,ifalldeviceshave
thesamepriority,thedevicewiththelowestMACaddresswillthen
becometheroot
device.
‐ Range:0‐65535
‐ Default:32768
Note: Note that lower numeric values indicate higher priority.