IBM NH2025-10 manual Spanning Tree Parameters, Manually Designating a Root Bridge

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Configuring, Modifying, and Monitoring the Unit

Spanning Tree Parameters

Normally, each switch or bridge in a network participates in STP. The units work together as peers to determine which links are to forward packets between LANs, and which links are to be blocked. Links that forward packets are chosen based on which link has the lowest pathcost and priority. Redundant paths are blocked, unless another link which is a forwarding link is deactivated, at which the blocked link will then go into a forwarding state.

NOTE: NBase-Xyplex switches are compatible with STP software that conforms to the IEEE 802.1D specification. They are not compatible with other STP versions that do not conform to this specification (for example, the DEC STP implementation). If you install a NH2025-10 switch in a network where other devices are using non-conforming (i.e., not 802.1D) STP, you must make sure that no loops exist in the network topology.

Root Bridge

Units that participate in STP compete to be the Root Bridge of the switched network. At start- up, each unit broadcasts an STP message called a Configuration Bridge Protocol Data Unit (Configuration BPDU) through each of its interfaces, announcing its bridge ID, including its priority value and MAC address. The unit with the lowest priority value is recognized as the Root Bridge. In the event of a tie, the unit with the lowest MAC address becomes the Root. After the STP topology stabilizes, Hello BPDUs are periodically sent by the Root bridge and are propagated down the Spanning Tree by other bridges in the switched network. Each bridge adds its own pathcost before forwarding.

Manually Designating a Root Bridge

By assigning priority values to the switches in your network, you can designate which unit is to be the Root Bridge, which is to be the 1st backup Root Bridge, 2nd backup Root Bridge, etc. There are no rules for selecting a Root Bridge. However, most commonly the Root is located in the middle of the network or at the corporate data center. For instructions on assigning Priority values, refer to the Spanning Tree Commands section.

Selecting a Designated Switch/Bridge

When a LAN has multiple switches connecting it to a remote LAN, the units compete to determine which can provide the best service to the LAN. The units that can provide the best service is recognized as the Designated Switch/Bridge for the LAN. Other units provide standby connections.

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Contents Page Page Standards Compliance FCC NoticeCE Mark Page Contents Configuring, Modifying, and Monitoring the Unit Iii Statistics Overview General ViewApplications Network Management SystemsFeature Summary Performance/ConfigurationManagement Page Rack Mounting Installing and Setting Up the UnitInstalling the Unit Front PanelInstalling Modules in the Unit Rear PanelModules for NH EM2003-1GEEM2003-2FO EM2003-8TP Connecting Power to the UnitInput Supply Em2003-2GEConnecting Ethernet Devices Connecting Your NetworkGrounding Page Setting the IP Address Connecting to the Management PortLogging Into the Command Line Interface Getting StartedSYSconsole set-ip Verifying the InstallationAccessing the Command Line Interface Remotely SYSconsole ping 192.1.1.1Command Line Help Using the Command Line InterfaceCommand Conventions Getting Command Parameter HelpGetting Command Group Help Using Command WildcardsSYSconsole ping 129.1.1.7 ? Retrieving Command History Connectivity matrixSYSconsoleget-co SYSconsole pin Command ‘pin’ not found Command Line ErrorsNonexistent Command Incorrect Number of ParametersCompletes command Configuring, Modifying, and Monitoring the UnitConsole Commands Help-kbdClear LoginBanner LogoutSet-passwd System Commands Sys-statGet-stst-level Warm-resetCold-reset Set-stst-levelSet-tftp-mode Get-tftp-srvrSet-tftp-srvr Get-tftp-modeGet-ip IP CommandsIP Configuration Get-ip-cfgSet-ip-cfg Setting an IP addressSet-ip IP broadcast SYSconsoleErasing an IP Configuration Configuring a GatewayBootp Configuration Del-arp-entry Address Resolution Protocol ARPGet-arp-tbl Add-arp-entryGet-arp-stats Port configurationDisplaying the Port Configuration Get-port-cfg dport pipe allSetting the port configuration Set-port-cfgSet-port-state Setting the flow control Get-fctrlSet-fctrl EtherChannel Getting the EtherChannel ConfigurationSetting the EtherChannel Configuration Get-ec-tbl Deleting the EtherChannel Configuration del-ec Port Priority Set Port Priority Vlan Priority Modifying the Switch PolicyGet Port Priority Get-priority-port-cfgSpanning Tree Protocol STP How the STP Topology StabilizesRoot Bridge Selecting a Designated Switch/BridgeSpanning Tree Parameters Manually Designating a Root BridgeTopology Change Notification Bpdu Using STP to Manage Redundant LinksSpanning Tree Commands Spanning Tree and Vlan restrictionsGet-st-bcfg Configuring the BridgeViewing Bridge Parameters Max Age set-br-maxageHello Time set-br-hellot Viewing the Port ConfigurationSetting Port Configuration Get-st-pcfgSet-prt-enb port-number enabledisable Set-prt-prio 4 Priority was changed for port SYSconsoleSet-prt-pcost dport pathcost Learning Table Switching CommandsAging Configuration Get-lt-ageGet-lt-entry Get-lt-16Find-lt-addr Deleting Entries Adding Static EntriesVirtual Broadcast Domain Viewing the VBC ModeSetting the VBC mode Creating VBC DomainsViewing VBC Matrix Get-vbc-tblGet-vbc-matrix Del-vbc-domain Virtual NetworkingDeleting a VBC Del-vbc-domain runnvram domainidSYSconsoleset-vlan-mode run tag Set run Vlan mode tag OK Viewing the Vlan ModeSetting the Vlan Mode Important ConsiderationsTag Field Format Inter-Switch Vlan or IsvlanViewing the Isvlan Mode Principles of IsvlanRemoving a Tagged Port Setting a Tagged PortServer Port Creating a Server PortViewing Vlan Configuration Removing a Server PortCreating a Vlan Deleting a Vlan Get-vlan-entryDel-vlan Modifying the Management Tag Vlan ManagementViewing the Management Tag Deleting the Management from a VlanVlan Server Port ConfigurationApplication VLAN, Server-port, Example of ConfigurationPhysical configuration schema Creating a Vlan with Port ManagementFinance Vlan Configuration Vlan ConfigurationPayroll Vlan Configuration Checking the ConfigurationPort mirroring Utilities CommandsPing Commands PingMonitoring with monitor Setting the Monitoring PortSaving the Configuration Stopping MonitoringSetting the Frame Generator Viewing the Nvram ConfigurationErasing the Nvram configuration Frame GeneratorSnmp basic configuration NBase-Xyplex Snmp SupportStopping the Frame Generation Viewing the Community String Snmp Community String CommandsSetting the Read or Write Community Get-commSetting the Authentication Trap Setting Authentication TrapsViewing the Authentication Trap Status Snmp TrapsConfiguring the Trap Stations Get-traps ExampleAdd-trap Getting Collisions on a Port Clearing the Switch CountersStatistics Clr-cntRmon Statistics Getting Rmon Statistics Group for a PortGetting the Packet Size Distribution Getting the Management Counters Page Trouble Shooting Mailservice@mrv.com Commands Quick Reference EtherChannel Commands Ping CommandsARP Commands Snmp CommandsSwitching Database Commands Virtual LAN CommandsPort Configuration Commands Switching Statistics CommandsPort Monitoring Spanning Tree Commands Page System Default Values SnmpPage Appendix B Firmware Download Using Tftp Download Procedure Client ModeDownload Procedure Server mode Tftp Recovery Breaking into the BootROM ∙ set-tftp-mode clientAppendix C Technical Specifications CompatibilityStandards Compliance
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