From the course: Cisco Certified Network Associate (CCNA) v1.1 (200-301) Cert Prep

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MSTP theory

MSTP theory

(light music) [Instructor] We know that with traditional spanning tree protocol, the triple E 802.1 D standard, we had what was called A CST, a common spanning tree, meaning that all VLANs shared the same spanning tree topology. They had the same root bridge, although the switches used the same root ports, all the links had the same designated ports. All the same ports were blocking on our switches for every single VLAN. And then Cisco recognized that that same topology might not be optimal for every VLAN we have. One VLAN might benefit from having one switch as the root, and another VLAN might benefit from having a different switch as the root just based on the traffic flow patterns. And Cisco came up with PVST plus per VLAN spanning tree protocol plus where each VLAN could get its own spanning tree instance. However, we might have lots of VLANs configured on our switches. If we had a couple of thousand VLANs, we could run a couple of thousand instances of spanning tree one for each…

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