CIST Root Port

The port on the that connects to the CIST root bridge is the (also known as the master port for s).

The CIST root port is the master port for all MSTIs in that region, and it is the only port that connects the entire region to the CIST root.

If a bridge is both the CIST root bridge and the CIST regional root bridge, there is no CIST root port on that bridge.