Type of Protecting ring. It can be either major ring or sub-ring. As per G.8032v2, they are defined as : Major Ring: A Major ring is the Ethernet ring that is connected on two ports to an interconnection node. Sub Ring :A sub-ring is an Ethernet ring which is connected to (an)other Ethernet ring(s) or network(s) through the use of a pair of interconnection nodes. On their own, the sub-ring links do not form a closed loop. A closed connection of traffic may be formed by the sub-ring links and one or more links, that are controlled by (an)other Ethernet ring(s) or network(s), between interconnection nodes