EX2500 Ethernet Switch Configuration Guide

In Figure 8, VLAN 1 and VLAN 2 belong to different Spanning Tree Groups. The two instances of Spanning Tree separate the topology without forming a loop. Both VLANs can forward packets between the switches without losing connectivity.

Figure 8: Two VLANs, Each on a Different Spanning Tree Group

VLAN 1, STG 1

Switch 1

Switch 2

VLAN 2, STG 2

VLAN 1 passes traffic on STG 1

VLAN 2 passes traffic on STG 2

PVRST Configuration Guidelines

This section provides important information about configuring Per VLAN Rapid

Spanning Tree Groups:

„By default, STGs 2 through 128 are empty, and STG 1 contains all configured VLANs until individual VLANs are assigned to other STGs. The EX2500 switch allows only one VLAN per STG, except for STG 1.

„If the ports are tagged, each port sends out a special BPDU containing the tagged information.

„When a tagged port belongs to more than one STG, the egress BPDUs are tagged to distinguish the BPDUs of one STG from those of another STG.

Configuring PVRST

This configuration shows how to configure PVRST+ on the switch.

1.Set the spanning-tree mode to PVRST+. ex2500(config)# spanning-tree mode pvrst

2.Configure port membership for VLAN 1 and VLAN 2. Define the STGs for each VLAN.

By default, port 1 is a member of VLAN 1, and VLAN 1 is assigned to STG 1. Add port 2 to VLAN 2, and assign VLAN 2 to STG 2.

ex2500(config)# vlan 2 ex2500(config-vlan)# enable ex2500(config-vlan)# member 2 ex2500(config-vlan)# stg 2 ex2500(config-vlan)# exit

38„ Per VLAN Rapid Spanning Tree

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Juniper Networks EX2500 manual Pvrst Configuration Guidelines, Configuring Pvrst