Understanding Multiple Spanning Tree
Multiple Spanning Tree (MST) implementation is defined by IEEE 802.1s. MST convergence is fast because it rides on top of RSTP. MST provides load-balancing capability without the scalability issues that are attached with legacy STP. MST allows for very large Layer 2 networks. It can accomplish this through various regions or domains that house specific Layer 2 devices. In the “Introducing Rapid Spanning Tree Protocol” section, the primary focus was on 802.1w. Here, the discussion is on the integration of 802.1s and 802.1w using Cisco switches.
Comparing MST to PVST+/CST
In PVST+, a single spanning-tree topology is built for each VLAN. Each VLAN will have its own legacy STP network. Consider the design shown ...