Juniper Networks EX2500 manual Rapid Spanning Tree Protocol, Port State Changes

Page 49

Chapter 3: Spanning Tree Protocol

When you remove a port from a VLAN that belongs to an STG, that port is removed from the STG. However, if that port belongs to another VLAN in the same STG, the port remains in the STG.

As an example, assume that port 1 belongs to VLAN 2, and VLAN 2 belongs to STG 2. When you remove port 1 from VLAN 2, port 1 is also removed from STG 2. The port moves to the default VLAN 1.

However, if port 1 belongs to both VLAN 1 and VLAN 2 and both VLANs belong to STG 1, removing port 1 from VLAN 2 does not remove port 1 from STG 1 because VLAN 1 is still a member of STG 1.

An STG cannot be deleted, only disabled. If you disable the STG while it still contains VLAN members, Spanning Tree will be off on all ports belonging to that VLAN.

The relationship between port, trunk groups, VLANs, and spanning trees is shown in Table 9.

Rapid Spanning Tree Protocol

Rapid Spanning Tree Protocol (RSTP) provides rapid convergence of the spanning tree and provides for fast re-configuration critical for networks carrying delay-sensitive traffic such as voice and video. RSTP significantly reduces the time to reconfigure the active topology of the network when changes occur to the physical topology or its configuration parameters. RSTP reduces the bridged-LAN topology to a single spanning tree.

RSTP parameters are configured in Spanning Tree Group 1. Spanning Tree Groups 2 through 128 do not apply to RSTP. There are new STP parameters to support RSTP, and some values to existing parameters are different.

RSTP is compatible with devices that run 802.1D (1998) Spanning Tree Protocol. If the switch detects 802.1D (1998) BPDUs, it responds with 802.1D

(1998)-compatible data units. RSTP is not compatible with Per VLAN Spanning Tree (PVST+) protocol.

Port State Changes

The port state controls the forwarding and learning processes of Spanning Tree. In RSTP, the port state has been consolidated to the following: discarding, learning, and forwarding. Table 10 compares the port states between 802.1D (1998) Spanning Tree and 802.1D (2004) Rapid Spanning Trees.

Table 10: RSTP vs. STP Port States

Operational Status	STP Port State	RSTP Port State

Enabled	Blocking	Discarding

Enabled	Listening	Discarding

Enabled	Learning	Learning

Enabled	Forwarding	Forwarding

Disabled	Disabled	Discarding

Rapid Spanning Tree Protocol 35

Image 49

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 TrunkingAppendixes Port Mirroring Overview Configuring Port MirroringIndexes 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 ConventionsDocumentation Feedback List of Technical PublicationsRequesting 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 SnmpUser Configuration Default 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 AccountsHow TACACS+ Authentication Works TACACS+ AuthenticationTACACS+ Authentication Features in the EX2500 Switch „ starttime „ stoptime „ elapsedtime „ disccause Configuring TACACS+ Authentication on the Switch Command Authorization and LoggingConfigure 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 ExampleEnable 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 ProtocolDetermining the Path for Forwarding BPDUs Bridge Protocol Data Units BPDUsBridge Priority Changing the Spanning Tree Mode Spanning Tree Group Configuration GuidelinesPort Priority Port Path CostRules for Vlan Tagged Ports Creating a VlanAdding and Removing Ports from STGs Port State Changes Rapid Spanning Tree ProtocolRstp Configuration Example Rstp Configuration GuidelinesPort Type and Link Type Edge PortWhy Do We Need Multiple Spanning Trees? Default Spanning Tree ConfigurationPer 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 GuidelinesTrunking Overview Ports and TrunkingStatistical Load Distribution Before Configuring Static Trunks Built-In Fault ToleranceTrunk 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 PacketsConfiguring Storm Control Using Storm Control FiltersBroadcast Storms Differentiated Services Concepts Using Dscp Values to Provide QoSAssured Forwarding Drop Precedence Class Per Hop BehaviorQoS Levels Use the following command to perform Dscp mappingDscp 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