![](/images/new-backgrounds/1207035/207035103x1.webp)
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
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
38 Per VLAN Rapid Spanning Tree