3Com 3 manual Ieee 802.1w standard

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34CHAPTER 4: USING RESILIENCE FEATURES

Rapid Spanning Tree The Rapid Spanning Tree (RSTP) is an enhanced Spanning Tree feature. Protocol (RSTP) RSTP implements the Spanning Tree Algorithm and Protocol, as defined in

the IEEE 802.1w standard.

3Com recommends that you use the Rapid Spanning Tree Protocol feature (enabled by default) to provide optimum performance for your network and ease of use.

Some of the benefits of RSTP are:

■Faster determination of the Active Spanning Tree topology throughout a bridged network.

■Support for bridges with more than 256 ports.

■Standard support for the Fast-Forwarding configuration of edge ports. This is currently supported by the 'Fast Start' implementation.

■Easy deployment throughout a legacy network, through backward compatibility:

■it will default to sending 802.1D style BPDU's on a port if it receives packets of this format.

■it is possible for some ports on a Switch to operate in RSTP (802.1w) mode, and other ports, for example those connected to a legacy Switch, to operate in STP (802.1D) mode.

■you have an option to force your Switch to use the legacy 802.1D version of Spanning Tree, if required.

What is STP? STP is a bridge-based system that allows you to implement parallel paths for network traffic and uses a loop-detection process to:

■Find and disable the less efficient paths (that is, the paths that have a lower bandwidth).

■Enable one of the less efficient paths if the most efficient path fails.

RSTP provides the same functionality as STP. For details on how the two systems differ, see “How RSTP Differs to STP” on page 38.

As an example, Figure 5 shows a network containing three LAN segments separated by three bridges. With this configuration, each segment can communicate with the others using two paths. Without STP enabled, this configuration creates loops that cause the network to overload.

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Contents

SuperStack 3Com Corporation 5400 Bayfront Plaza Santa Clara, California Contents Using Multicast Filtering Status Monitoring and Statistics IP Addressing About this Guide Conventions List conventions that are used throughout this guideComments RelatedDocumentation Pddtechpubscomments@3com.comProduct RegistrationSwitch Features Page Management What isSwitch Features Software?Switch Features Overview Duplex Ports operating at 1000 Mbps only support full duplex modeFor more information about multicast filtering, see Using Flow ControlFor more information about STP and RSTP, see Using Resilience FeaturesFor more information about Quality of Service, see Using Quality of ServiceEvent Notification For more information about VLANs, see Setting Up Virtual Port Features Ports operating at 1000 Mbps support full duplex mode only Port Features Switch units connected using an aggregated link Aggregated Links Traffic Distribution and Link Failure on Aggregated Links 2 Gbps aggregated link between two Switch units Optimizing Bandwidth Using Multicast Filtering Relevant multicast groupUsing Multicast Filtering Snooping Mode Query modeQuery Mode Igmp multicast filtering works as follows Igmp v2 protocolThat support IP Enabling Igmp Multicast Learning Igmp Multicast Filtering Using Multicast Filtering Protocol STP Spanning TreeNetwork Ieee 802.1w standard What is STP? Traffic flowing through Bridge B Port Speed Link Type Path Cost 802.1D-1998 802.1w Using Resilience Features Port costs in a network Configuration 2 Redundancy through Meshed Backbone Configuration 1 Redundancy for Backbone LinkConfiguration 3 Redundancy for Cabling Error STP configurations Network with Default BehaviorUsing STP on a Multiple VLANsConfiguration that separates VLANs Using Resilience Features Database? What is the SwitchHow Switch Database EntriesSwitch Database Entry States Databases entries can have three statesAvailable What is TrafficPrioritization? Converged network applications Used by organizations with a802.1D Priority Levels How Traffic Prioritization Works Your Switch Traffic PrioritizationHow traffic is processed to provide Quality of Service Configuring traffic prioritization for QoS on a SwitchUsing Traffic Prioritization Network efficiency and reduce the load on your network What is RMON?That allows you to monitor the traffic of LANs or VLANs Events AlarmsIt improves your efficiency Switch RmonLow Threshold Statistic High Threshold Recovery Period Low Threshold Statistic High Threshold Recovery Status Monitoring and Statistics Hardware Status Monitoring Example device summary web Setting UP Virtual Lans VLANs ease the movement of devices on networks VLANs provide extra securityVLANs help to control traffic Membership Creating an Ieee 802.1Q Tagged LinkTwo Vlans connected via a router Configure the VLANs ConfigurationUsing Untagged ExamplesAdd endstation ports on Switch 1 to the VLANs Configure the VLANs on SwitchAdd ports to the VLANs Add port 11 on Switch 2 to the VLANs Add port 12 on Switch 1 to the VLANsAdd endstation ports on Switch 2 to the VLANs Check the Vlan membership for both switchesConfiguration Information How Your SwitchObtains IP How Automatic IPHow Automatic IP Configuration Works That a Switch may change its IP address whilst in use Automatic IP configuration featureConsiderations Glossary Configuration RulesIP Addressing IndexPage Configuration Rules Configuration Rules for Gigabit EthernetFast Ethernet configuration rules Configuration Rules for Fast Ethernet Appendix a Configuration Rules Network This chapter contains the following sectionsFamily and 4900 family can be used in your network Segments are connected to the Switch which is positionedSimple Network ExampleDual Speed Hub Switch Resilience of Your Advanced NetworkImproving NetworkPerformance EnhancingTherefore the overall network performance IP Addresses Simple OverviewObtaining a Registered IP Address IP AddressDecimal value of an octet whose bits are all 1s is Dotted Decimal NotationNetwork Portion Subnet mask Subnet Mask Numbering Extending the Network PrefixOr leave the field blank Glossary Glossary Ethernet address EndstationEthernet Fast EthernetHub GatewayHalf duplex Ieee 802.1DLine speed See baud Glossary Rstp See Rapid Spanning Tree Protocol STP See Spanning Tree Protocol STP Page Glossary Index NumbersIgmp multicast filtering 30 Internet Addresses 85 InterNIC Sub-networks. See subnets Switch Database

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