Port costs in a network | 3Com 3 guide

How STP Works 39

Figure 8 Port costs in a network

■Bridge A has the lowest Bridge Identifier in the network, and has therefore been selected as the Root Bridge.

■Because Bridge A is the Root Bridge, it is also the Designated Bridge for LAN segment 1. Port 1 on Bridge A is therefore selected as the Designated Bridge Port for LAN Segment 1.

■Port 1 of Bridges B, C, X and Y have been defined as Root Ports because they are the nearest to the Root Bridge and therefore have the most efficient path.

■Bridges B and X offer the same Root Path Cost for LAN segment 2, however, Bridge B has been selected as the Designated Bridge for the segment because it has a lower Bridge Identifier. Port 2 on Bridge B is therefore selected as the Designated Bridge Port for LAN Segment 2.

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3Com 3 manual Port costs in a network

Contents

SuperStack 3Com Corporation 5400 Bayfront Plaza Santa Clara, California Contents Using Multicast Filtering Status Monitoring and Statistics IP Addressing About this Guide List conventions that are used throughout this guide Conventions Pddtechpubscomments@3com.com RelatedDocumentation Comments Registration Product Switch Features Page Software? What isSwitch Features Management Switch Features Overview Flow Control Ports operating at 1000 Mbps only support full duplex modeFor more information about multicast filtering, see Using Duplex Resilience Features For more information about STP and RSTP, see Using Quality of Service For more information about Quality of Service, see UsingEvent 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 Relevant multicast group Using Multicast Filtering Using Multicast Filtering Query mode Snooping ModeQuery Mode Enabling Igmp Multicast Learning Igmp v2 protocolThat support IP Igmp multicast filtering works as follows Igmp Multicast Filtering Using Multicast Filtering Spanning Tree Protocol STPNetwork 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 1 Redundancy for Backbone Link Configuration 2 Redundancy through Meshed BackboneConfiguration 3 Redundancy for Cabling Error STP configurations Multiple VLANs Default BehaviorUsing STP on a Network with Configuration that separates VLANs Using Resilience Features Database Entries What is the SwitchHow Switch Database? Databases entries can have three states Switch Database Entry States Converged network applications Used by organizations with a What is TrafficPrioritization? Available 802.1D Priority Levels How Traffic Prioritization Works Traffic Prioritization Your Switch Configuring traffic prioritization for QoS on a Switch How traffic is processed to provide Quality of Service Using Traffic Prioritization What is RMON? Network efficiency and reduce the load on your networkThat allows you to monitor the traffic of LANs or VLANs Alarms EventsIt improves your efficiency Rmon Switch Low 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 provide extra security VLANs ease the movement of devices on networks VLANs help to control traffic Creating an Ieee 802.1Q Tagged Link Membership Two Vlans connected via a router Examples ConfigurationUsing Untagged Configure the VLANs Configure the VLANs on Switch Add endstation ports on Switch 1 to the VLANsAdd ports to the VLANs Check the Vlan membership for both switches Add port 12 on Switch 1 to the VLANsAdd endstation ports on Switch 2 to the VLANs Add port 11 on Switch 2 to the VLANs Configuration How Automatic IP How Your SwitchObtains IP Information How Automatic IP Configuration Works Automatic IP configuration feature That a Switch may change its IP address whilst in useConsiderations Index Configuration RulesIP Addressing GlossaryPage Configuration Rules for Gigabit Ethernet Configuration Rules Fast Ethernet configuration rules Configuration Rules for Fast Ethernet Appendix a Configuration Rules This chapter contains the following sections Network Example Segments are connected to the Switch which is positionedSimple Network Family and 4900 family can be used in your network Dual Speed Hub Switch Network Advanced NetworkImproving Resilience of Your Enhancing PerformanceTherefore the overall network performance Simple Overview IP Addresses IP Address Obtaining a Registered IP Address Dotted Decimal Notation Decimal value of an octet whose bits are all 1s isNetwork Portion Subnet mask Extending the Network Prefix Subnet Mask Numbering Or leave the field blank Glossary Glossary Fast Ethernet EndstationEthernet Ethernet address Ieee 802.1D GatewayHalf duplex Hub Line speed See baud Glossary Rstp See Rapid Spanning Tree Protocol STP See Spanning Tree Protocol STP Page Glossary Numbers Index Igmp multicast filtering 30 Internet Addresses 85 InterNIC Sub-networks. See subnets Switch Database