Juniper Networks EX2500 manual Spanning Tree Protocol, Spanning Tree Overview

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Chapter 3

Spanning Tree Protocol

When multiple paths exist on a network, Spanning Tree Protocol configures the network so that a switch uses only the most efficient path.

The following topics are discussed in this chapter:

Spanning Tree Overview on page 31

Rapid Spanning Tree Protocol on page 35

Per VLAN Rapid Spanning Tree on page 37

Multiple Spanning Tree Protocol on page 39

Fast Uplink Convergence on page 41

Spanning Tree Overview

Spanning Tree Protocol (STP) detects and eliminates logical loops in a bridged or switched network. When multiple paths exist, Spanning Tree configures the network so that a switch uses only the most efficient path. If that path fails, Spanning Tree automatically sets up another active path on the network to sustain network operations.

The EX2500 switch supports the following Spanning Tree Protocols:

IEEE 802.1D (2004) Rapid Spanning Tree Protocol (RSTP). RSTP enhances the Spanning Tree Protocol to provide rapid convergence on Spanning Tree Group 1.

IEEE 802.1Q (2003) Multiple Spanning Tree Protocol (MSTP), which extends RSTP to multiple Spanning Tree Groups (STGs). MSTP provides both rapid convergence and load balancing in a VLAN environment, using multiple VLANs in each Spanning Tree Group (STG).

Per VLAN Rapid Spanning Tree Plus Protocol (PVRST+), which enhances the RSTP protocol by adding the ability to have multiple Spanning Tree Groups. PVRST+ is based on IEEE 802.1w Rapid Spanning Tree Protocol.

Spanning Tree Overview 31

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Contents North Mathilda Avenue Sunnyvale, CA Configuration GuideIi „ Table of Contents Chapter VLANs Rmon Overview Rmon Group 1-Statistics Rmon Group 2-History Chapter Ports and TrunkingPort Mirroring Overview Configuring Port Mirroring AppendixesIndexes Port-Based Vlan Assignment Default Vlan SettingsPage List of Tables EX2500 Ethernet Switch Configuration Guide „ List of Tables Objectives About This GuideAudience Supported PlatformsIcon Meaning Description Documentation ConventionsList of Technical Publications Documentation FeedbackRequesting Technical Support Opening a Case with Jtac Self-Help Online Tools and ResourcesEX2500 Ethernet Switch Applications Page Configuring the Management Interface Accessing the SwitchConfigure the default gateway. Enable the gateway Dynamic Host Configuration ProtocolUsing the EX2500 Web Device Manager Using TelnetConfiguring EX2500 Web Device Manager Access via Https Configuring EX2500 Web Device Manager Access via HttpSNMPv1, SNMPv2 Using SnmpDefault Configuration User ConfigurationSNMPv3 SNMPv1 Trap Host Configuration Configuring Snmp Trap HostsSNMPv2 Trap Host Configuration Configure an entry in the notify tableSNMPv3 Trap Host Configuration Securing Access to the SwitchHow Radius Authentication Works Radius Authentication and AuthorizationConfiguring Radius on the Switch Configure the Radius secretRadius Authentication Features in the EX2500 Switch Radius Attributes for EX2500 User Privileges Switch User AccountsTACACS+ Authentication How TACACS+ Authentication WorksTACACS+ Authentication Features in the EX2500 Switch „ starttime „ stoptime „ elapsedtime „ disccause Command Authorization and Logging Configuring TACACS+ Authentication on the SwitchConfigure the TACACS+ secret and second secret Generating RSA Host and Server Keys for SSH Access Configuring SSH Features on the SwitchSecure Shell SSH Encryption of Management MessagesSSH Integration with Radius and TACACS+ Authentication End User Access ControlUser Access Control Considerations for Configuring End User AccountsLogging In to an End User Account Listing Current UsersVlan Overview VLANsVLANs and Port Vlan ID Numbers „ Port configurationVlan Numbers Pvid NumbersVlan Tagging Illustrates the default Vlan settings on the switchDefault Vlan Settings Port-Based Vlan Assignment Vlan Topologies and Design Considerations Vlan Configuration RulesMultiple VLANs example in is described in Table Multiple VLANs Configuration Example Enable tagging on uplink ports that support multiple VLANs Private Vlan Ports Private VLANsPrivate Vlan Configuration Example Private Vlan Configuration GuidelinesConfigure a secondary Vlan and map it to the primary Vlan Verify the configurationSpanning Tree Overview Spanning Tree ProtocolBridge Protocol Data Units BPDUs Determining the Path for Forwarding BPDUsBridge Priority Changing the Spanning Tree Mode Spanning Tree Group Configuration GuidelinesPort Priority Port Path CostCreating a Vlan Rules for Vlan Tagged PortsAdding and Removing Ports from STGs Port State Changes Rapid Spanning Tree ProtocolRstp Configuration Example Rstp Configuration GuidelinesPort Type and Link Type Edge PortDefault Spanning Tree Configuration Why Do We Need Multiple Spanning Trees?Per Vlan Rapid Spanning Tree Configuring Pvrst Pvrst Configuration GuidelinesMultiple Spanning Tree Protocol Mstp Configuration GuidelinesMstp Region Common Internal Spanning TreeImplementing Multiple Spanning Tree Groups Multiple Spanning Tree Groups Configuration ExampleVlan Fast Uplink ConvergenceConfiguring Fast Uplink Convergence Configuration GuidelinesPorts and Trunking Trunking OverviewStatistical Load Distribution Built-In Fault Tolerance Before Configuring Static TrunksTrunk Group Configuration Rules Port Trunk Group Configuration Example Port Trunking Configuration ExampleFollow these steps on the EX2500 switch Define a trunk group Link Aggregation Control Protocol Configurable Trunk Hash Algorithm„ Destination MAC Dmac „ Destination IP DIP48 „ Link Aggregation Control Protocol Configuring Lacp Lacp Configuration GuidelinesOptionally Reducing Lacp Timeout Set the Lacp modeEx2500config-if# lacp timeout short ex2500config-if# exit QoS Overview Quality of ServiceCOS Using ACL FiltersIP Standard ACLs MAC Extended ACLsTo delete a MAC Extended ACL To delete an IP Standard ACLTo delete an IP Extended ACL IP Extended ACLsTCP/UDP Understanding ACL PriorityAssigning ACLs to a Port ACL Configuration ExamplesViewing ACL Statistics ACL Example 1-Blocking Traffic to a HostAdd the ACL to a port ACL Example 3-Blocking Http TrafficAssign the ACLs to a port ACL Example 4-Blocking All Except Certain PacketsUsing Storm Control Filters Configuring Storm ControlBroadcast Storms Differentiated Services Concepts Using Dscp Values to Provide QoSAssured Forwarding Drop Precedence Class Per Hop BehaviorUse the following command to perform Dscp mapping QoS LevelsDscp Mapping Shows the priority bits in a VLAN-tagged packet Using 802.1p Priority to Provide QoSQueuing and Scheduling Rmon Overview Remote MonitoringRmon Group 1-Statistics Configure the Rmon statistics on a portConfigure the Rmon History parameters for a port Configuring Rmon HistoryThis configuration enables Rmon History collection on port Rmon Group 2-HistoryAlarm MIB Objects Rmon Group 3-AlarmsConfiguring Rmon Alarms Configure the Rmon Alarm parameters to track Icmp messagesRmon Group 9-Events Ex2500config# rmon event 110 type log-onlyPage Igmp Snooping IgmpFastLeave IGMPv3 Snooping Igmp Snooping Configuration ExampleEx2500# show ip igmp groups Static Multicast RouterHigh Availability Overview High Availability Through Uplink Failure DetectionFailure Detection Pair Spanning Tree Protocol with UFD UFD Configuration GuidelinesMonitoring UFD UFD Configuration ExamplePage Appendixes EX2500 Ethernet Switch Configuration Guide 80 „ Appendixes Port Mirroring Overview „ Port Mirroring Overview on „ Configuring Port Mirroring onConfiguring Port Mirroring „ Index on IndexesEX2500 Ethernet Switch Configuration Guide 84 „ Indexes Numerics IndexMulti-links between switches, port trunking Management interface, configuringPhysical. See switch ports Internet Group Management Protocol. See IgmpQoS Quality of Service. See QoSSecurity Segmentation. See IP subnets Segments. See IP subnetsExample showing multiple VLANs Virtual Local Area Networks. See VLANs