Enterasys Networks VH-2402S manual Spanning Tree Protocol Operation

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Spanning Tree Protocol Operation

When the Spanning Tree Protocol is enabled for the first time or when there is a change in the network topology, such as a failure or the addition or removal of a component, the Spanning Tree Protocol automatically sets up the active topology of the current network.

Communicating Between Bridges

Periodically, all devices running the Spanning Tree Protocol on a network transmit packets to each other “in care of” the Bridge Group Address which all bridges share. When a bridge receives a frame sent to the Bridge Group Address, the bridge’s Spanning Tree Protocol processes the packet. Application software and other LAN segments ignore the packet. Bridges communicate between each other in order to determine the Root Bridge.

Selecting a Root Bridge and Designated Bridges

During communication between bridges, one bridge is determined to have the lowest bridge identifier. This bridge becomes the Root Bridge.

After the Root Bridge has been selected, each LAN segment looks for the bridge that has the lowest cost relative to the Root Bridge. These bridges become Designated Bridges.

Selecting Designated Ports

Each Designated Bridge selects a Designated Port. This port is responsible for forwarding packets to the Root Bridge.

Handling Duplicate Paths

When the active topology of the network is determined, all packets between any two nodes in the network use only one path. Where a duplicate path exists, the non-designated port is put into a blocking state.

Remapping Network Topology

If there is a change in the network topology due to a failure or the removal or addition of any active components, the active topology also changes. This may trigger a change in the state of some blocked ports.

88 Spanning Tree Concepts

VH-2402S

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Contents Fast Ethernet Switch Management GuidePage 9033645-01 9033645-01 Table of Contents Snmp Management Appendix A. Spanning Tree ConceptsIndex Vi Table of Contents VH-2402S Configuration Options Management OverviewRequired Connections Console Port Out-of-Band ConnectionsConfigure the Switch Site Configure the Remote SiteRemote Management via the Console Port In-Band ConnectionsIn-Band Network Connection Management Overview VH-2402S VH-2402S User Interface OverviewUser Access Factory Defaults Factory Default SettingsGvrp Main Menu Selection DescriptionDisplays/configures extended bridge capabilities provided by System Information Menu System Information MenuDisplaying System Information System InformationDisplaying Switch Version and Module Information Switch InformationManagement Setup Menu Management Setup MenuChanging the Network Configuration Network ConfigurationIP Configuration IP ConfigurationIP Connectivity Test Ping IP Connectivity TestHttp Configuration 10. Http ConfigurationConfiguring the Serial Port 11. Serial Port Configuration12. Snmp Configuration Assigning Snmp ParametersConfiguring Community Names 13. Snmp CommunitiesConfiguring IP Trap Managers 14. IP Trap ManagersConsole Login Configuration 15. Console Login ConfigurationUsing Tftp Protocol to Download Over the Network Downloading System SoftwareSaving the System Configuration Parameter DescriptionConfiguring Management Access 18. Management ConfigurationConfiguring the Switch 19. Device Control MenuNot implemented in the current firmware release Configuring Port Parameters 20. Port ConfigurationViewing the Current Port Configuration 21. Port InformationUsing the Spanning Tree Algorithm 22. Spanning Tree Configuration Configuring Bridge STADevice with the lowest MAC address will then Configuring STA for Ports or Modules 24. Spanning Tree Port ConfigurationViewing the Current Spanning Tree Configuration 25. Spanning Tree InformationDisplaying the Current Bridge STA 26. Bridge STA InformationDisplaying the Current STA for Ports or Modules 27. Spanning Tree Port InformationRules defining port status are Using a Mirror Port for Analysis 28. Mirror Port ConfigurationConfiguring Port Trunks 29. Port Trunking Configuration Igmp Multicast Filtering Configuring Igmp 30. Igmp ConfigurationConfiguring Broadcast Storm Control 31. Broadcast Storm Control ConfigurationConfiguring Bridge MIB Extensions 32. Extended Bridge ConfigurationBy setting this parameter to False Configuring Traffic Classes 33 .1P ConfigurationPort Priority Configuration 34 .1P Port Priority Configuration802.1P Port Traffic Class Information 35 .1P Port Traffic Class InformationConfiguring Virtual LANs 802.1Q Vlan Base Information802.1Q Vlan Current Table Information 37 .1Q Vlan Current Table Information802.1Q Vlan Static Table Configuration 38 .1Q Vlan Static Table Configuration39 .1Q Vlan Static Table Configuration Example Port Assignment Vlan Configuration 40. Port Assignment Vlan ConfigurationMulticast Router Port Information 41. Multicast Router Port InformationStatic Multicast Router Port Configuration 42. Static Multicast Router Port ConfigurationIgmp Member Port Configuration 43. Igmp Member Port ConfigurationPort Security Configuration 44. Port Security ConfigurationMonitoring the Switch 45. Network Monitor MenuDisplaying Port Statistics 46. Port StatisticsDisplaying Rmon Statistics 47. Rmon StatisticsDrop Events Displaying the Unicast Address Table 48. Unicast Address TableDisplaying the IP Multicast Registration Table 49. IP Multicast Registration TableConfiguring Static Unicast Addresses 50. Static Unicast Addreeess Table ConfigurationResetting the System Logging Off the System66 VH-2402S User Interface Configuring & Monitoring the Switch Common TasksSetting Password Protection Checking Network Configuration Status Connecting via TelnetAssigning an IP Address Setting Snmp Management Access Viewing Switch StatisticsConfiguring Port Mirroring Downloading a Software UpgradeDownloading Via the Serial Port Downloading Via Tftp9033645-01 Configuring Spanning Tree Parameters Configuring VLANs Configuring Class of ServiceConfiguring Port Operation Configuring the Unicast Address Table Setting a Default Gateway Configuring BootPConfiguring Port Trunks Configuring & Monitoring the Switch VH-2402S Snmp Management Snmp ProtocolMIB Objects RFC 1213 MIB-II RFC 1573 Interfaces Evolution MIBRFC 1643 Ethernet-Like MIB RFC 1493 Bridge MIBCompiling MIB Extensions Enterasys Website Ieee 802.1Q Q-MIBEnterasys Proprietary MIB Extensions Spanning Tree Features Appendix A. Spanning Tree ConceptsGeneral Figure A-1. Spanning Tree Using VH-2402S Switches Spanning Tree Protocol in a NetworkTable A-1. Spanning Tree Protocol Defaults Spanning Tree Protocol ParametersSpanning Tree Protocol Operation 9033645-01 Spanning Tree Concepts VH-2402S Appendix B. Virtual Lans Vlans VLANs and Frame TaggingVH-2402S Vlan Configuration Assigning Ports to VLANsVlan Classification Port OverlappingForwarding Tagged/Untagged Frames Automatic Vlan RegistrationForwarding Traffic with Unknown Vlan Tags Appendix C. Class of Service Incoming tagged frames contain a priority level rangeFigure C-1. Class of Service Example Appendix D. IP Multicast Filtering Igmp Snooping and IP Multicast FilteringPage Index Tftp Page 150524-103 R02