What is one benefit of PVST+?
PVST+ stands for Per VLAN Spanning Tree Plus. It is a Cisco proprietary protocol that is an enhancement of the original IEEE 802.1D Spanning Tree Protocol (STP). PVST+ provides a separate 802.1D spanning tree instance for each VLAN configured in the network.
The benefit of PVST+ is that it allows the root switch location to be optimized per VLAN (Option C). In a network with multiple VLANs, there may be a need to have different root switches for different VLANs. This is because different VLANs may have different traffic patterns, and having a root switch in a suboptimal location can lead to suboptimal traffic flows. With PVST+, each VLAN can have its own root switch, which can be optimized for the specific traffic pattern of that VLAN.
Option A is incorrect because PVST+ does not directly support Layer 3 load balancing without loops. Layer 3 load balancing is typically done using protocols like OSPF or EIGRP. PVST+ is a Layer 2 protocol that is concerned with loop prevention in the Layer 2 switching domain.
Option B is incorrect because PVST+ does not reduce the CPU cycles for all the switches in the network. In fact, PVST+ can increase the CPU load on switches, especially in networks with many VLANs. This is because each VLAN has its own spanning tree instance, which can increase the computational load on the switches.
Option D is incorrect because PVST+ does not automatically select the root bridge location. The root bridge location must be manually configured or allowed to be determined through the STP election process. PVST+ simply allows for multiple root bridges, one per VLAN, to be configured in the network.