Which AOS-CX supported version of Spanning-Tree allows the use of different instances mapped to one or more VLANs?

The supported version of Spanning-Tree that allows the use of different instances mapped to one or more VLANs is IEEE 802.1s, also known as Multiple Spanning Tree Protocol (MSTP). This protocol enhances the Spanning Tree Protocol (STP) by allowing multiple VLANs to be mapped to a single spanning tree instance. As a result, MSTP can create a more efficient network by reducing the number of active spanning tree instances while maintaining the benefits of loop prevention and redundancy.

MSTP works by defining a mapping between VLANs and the spanning tree instances. This mapping allows network administrators to tailor specific instances for different sets of VLANs, resulting in optimized traffic flows and resource use in large networks. The ability to consolidate multiple VLANs under a single spanning tree instance helps in reducing the overhead and complexity associated with maintaining multiple individual spanning trees for each VLAN.

This capacity to support multiple instances is what distinctly sets MSTP apart from the other Spanning Tree versions. Other options, like STP and Rapid Spanning Tree Protocol (RSTP), only operate at a single-instance level and do not provide the flexibility of VLAN-to-instance mapping like MSTP does.