Was Ist Spaning Tree?

The IST is the only spanning-tree instance that sends and receives BPDUs; all of the other spanning-tree instance information is contained in M-records, which are encapsulated within MSTP BPDUs.

What is STP CIST?

3.22 Common and Internal Spanning Tree (CIST): The single Spanning Tree calculated by STP and RSTP together with the logical continuation of that connectivity through MST Bridges and regions, calculated by MSTP to ensure that all LANs in the Bridged Local Area Network are simply and fully connected.

Does MST use Rapid Spanning Tree?

When you configure MST there is always one default instance used to calculate the topology within the region. We call this the IST (Internal Spanning Tree). By default Cisco will use instance 0 to run the IST. In case you were wondering…its rapid spanning tree that we run within the MST.