Additionally, comparisons and calculations done by each bridge select a CIST priority vector for each Port (based on priority vectors, MST Configuration Identifiers and on an incremental Path Cost associated to each receiving port). This leads to one bridge been selected as the CIST Root of the Bridged LAN; then, a minimum cost path to the root is shifted out for each Bridge and LANs (thus preventing loops and ensuring full connectivity between VLANs). Subsequently, in each region, the bridge whose minimum cost path to the root doesn't pass through another bridge with the same MST Conf.ID will be identified as its Region's CIST Regional Root. Conversely, each Bridge whose minimum cost path to the Root is through a Bridge using the same MST Configuration Identifier is identified as being in the same MST Region as that Bridge.