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So here’s a quick comparison of the different versions of Spanning Tree.

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The Spanning Tree 802.1D protocol doesn’t need a lot of resources

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but it slow to converge.

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You only have 1 Spanning Tree instance for your entire layer 2 network.

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This can lead to sub-optimal traffic flows

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and 802.1D is generally not used today in Cisco environments.

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Just be aware that when you use newer versions of Spanning Tree

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Cisco switches are backward compatible

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and can talk to all the switches or non-Cisco switches using 802.1D

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PVST is the Cisco enhancement

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that provides a single instance of Spanning Tree per-VLAN.

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It's Cisco propriety, it needs more resources

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because 1 Spanning Tree instance is created per-VLAN.

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It is still slow to converge but thus allow you to split traffic flows

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because you have 1 Spanning Tree instance per VLAN.

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as an example, VLAN 1 traffic could use 1 uplink

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but VLAN 2 traffic could use as separate uplink or a separate port in a network.

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Cisco have also enhanced PVST with features

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such as Portfast, Uplink fast, backbone fast, BPDU guard, BPDU filter

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root guard and loop guard we'll discuss some of those terms in this course

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otherwise, you'll learn more about those when you attend your CCMP courses.

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Rapid Spanning Tree Protocol or 802.1W is an industry standard protocol

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it doesn’t need as many resources as PVST+

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because it supports a single instance of Spanning Tree for your layer 2 network.

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Its big advantage is that it provides very quick or fast convergence.

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It also doesn’t address suboptimal traffic flow issues

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because you can send VLAN 10 traffic for example down 1 link

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and VLAN 20 traffic down another link.

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That’s the advantage of Rapid PVST+

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Rapid PVST+ incorporates the advantages of Rapid Spanning Tree

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but allows you to create 1 spanning tree instance per-VLAN

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so you can do load sharing of traffic, it provides very quick convergence

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but uses a lot of resources especially when you’ve got many VLANs.

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The advantage of Multiple Spanning Trees

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is that it solves that high resource issue of PVST+

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Multiple Spanning Trees allows you to create an instance of Spanning Tree

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and then map various VLANs to that instance.

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As an example, once again if you had 200 VLANs PVST or Rapid PVST

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would require 200 instances of Spanning Tree

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where’s Multiple Spanning Tree could use 2 instances to do load sharing

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and reduce the amount of resources required.

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So CPU and memory requirements for Multiple Spanning Trees

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are lower than those for Rapid PVST+

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but resources are higher than those for Rapid Spanning Tree.

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Now you may find reference materials stating that PVST+

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is the default Spanning Tree on Cisco switches

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that really depends on a lot of switches today use Rapid PVST

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is the default version of Spanning Tree.