STP - MST Virtual Bridge and its role in interfacing with other STP topologies

In the context of Multiple Spanning Tree (MST), the "Virtual Bridge" is a virtual entity created by the MST region to interface with Spanning Tree Protocol (STP) topologies outside the MST domain. This virtual bridge is perceived by external switches as a single bridge with a specific bridge ID.

The virtual bridge is not a physical switch but a construct within the MST domain. The best bridge ID is determined from all switches in instance 0 of the MST domain and shared with external switches. Consequently, any switch outside the MST domain connected to an MST switch will see the entire MST domain as a single switch with the determined bridge ID. This allows seamless communication and BPDU exchange between MST and non-MST regions.

See also: STP - MST Virtual Bridge and its role in interfacing with other STP topologies.

Links

https://forum.networklessons.com/t/multiple-spanning-tree-mst/1101/88?u=lagapidis

https://networklessons.com/spanning-tree/multiple-spanning-tree-mst

https://networklessons.com/cisco/ccie-routing-switching-written/mst-pvst-interoperability