300-320 Question #453: Real Exam Question with Answer & Explanation

The correct answer is A: MSTP. MSTP (Multiple Spanning Tree Protocol), defined in IEEE 802.1s (later incorporated into 802.1Q), is the only standards-based STP variant that supports mapping multiple VLANs to a reduced number of spanning tree instances. It is vendor-neutral, making it suitable for multi-vendor

Question

A LAN infrastructure consists of switches from multiple vendors. Spanning Tree is used as a Layer 2 loop prevention mechanism. All configured VLANs must be grouped in two STP instances. Which standards-based Spanning Tree technology must be used?

Options

AMSTP
BRapid PVST
CSTP
DRSTP

Explanation

MSTP (Multiple Spanning Tree Protocol), defined in IEEE 802.1s (later incorporated into 802.1Q), is the only standards-based STP variant that supports mapping multiple VLANs to a reduced number of spanning tree instances. It is vendor-neutral, making it suitable for multi-vendor environments. Rapid PVST+ (option B) is Cisco-proprietary and creates one STP instance per VLAN, not grouped instances. Standard STP (802.1D) and RSTP (802.1w) operate as a single instance for all VLANs and cannot group VLANs into specific instances.

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