The Benefit of PVST+

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PVST+ (Per-VLAN Spanning Tree Plus) is an advanced version of the Spanning Tree Protocol (STP) that Cisco developed to address some of the limitations of STP. STP is used to prevent network loops by creating a loop-free topology in a network. PVST+ extends this functionality by allowing STP to be configured on a per-VLAN basis, which means that a separate instance of STP is run for each VLAN.

One benefit of PVST+ is that it allows the root switch location to be optimized per VLAN. This means that different VLANs can have different root switches, which can improve network performance by reducing the distance that data has to travel between switches. By default, STP selects the switch with the lowest bridge ID as the root bridge, which may not be the best choice for all VLANs. With PVST+, administrators can manually set the root bridge for each VLAN, which can be especially useful in large networks with many VLANs.

Option A, "PVST+ reduces the CPU cycles for all the switches in the network," is not a benefit of PVST+. PVST+ does not reduce CPU cycles; it actually uses more CPU resources than traditional STP because it runs a separate instance of STP for each VLAN.

Option B, "PVST+ automatically selects the root bridge location to provide optimized bandwidth usage," is not accurate. PVST+ does not automatically select the root bridge; it allows administrators to manually set the root bridge for each VLAN.

Option D, "PVST+ supports Layer 3 load balancing without loops," is also incorrect. PVST+ does not provide Layer 3 load balancing; it only addresses Layer 2 loops in a network.