Per-Vlan Spanning Tree Plus - Avaya 8800 Planning And Engineering, Network Design

Layer 2 loop prevention
Configure the four VLANs on the Layer 2 switch to include the tagged ports connected to the
Ethernet Routing Switch 8800/8600. To ensure that the BPDUs from STG2 and STG3 are seen by
the Layer 2 switch as traffic for the two VLANs, and not as BPDUs, give two of the VLANs the IDs
4002 and 4003. Figure 32: VLANs on the Layer 2 switch
configured on the Ethernet Switch 8100 and the traffic associated with each VLAN.
After you configure the Ethernet Switch 8100, configure VLAN 2 and VLAN 3 on the Ethernet
Routing Switch 8800/8600s.
The IDs of these two VLANs are important because they must have the same ID as the BPDUs
generated from them. The BPDUs generated from these VLANs is tagged with a TaggedBpduVlanId
that is derived by adding 4000 to the STG ID number. For example, for STG3 the
TaggedBpduVlanId is 4003.
Figure 32: VLANs on the Layer 2 switch

Per-VLAN Spanning Tree Plus

PVST+ is the Cisco-proprietary spanning tree mechanism that uses a spanning tree instance per
VLAN. PVST+ is an extension of the Cisco PVST with support for the IEEE 802.1Q standard. PVST
+ is the default spanning tree protocol for Cisco switches and uses a separate spanning tree
June 2016 Planning and Engineering — Network Design
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on page 100 illustrates the four VLANs
100