Metropolitan ring networks are usually used to connect the high speed backbone networks with the high speed access networks. Until now, metropolitan networks and access networks are gained much attention of researchers just as in separate direction. Indeed, the end-to-end metropolitan performance of a multi-ring architecture, in which metropolitan access networks are interconnected by a metropolitan core network, has been recently investigated as well as Ethernet-based passive optical access network (EPON) performance. In multi-ring architecture, the metro core and metro access interconnect via a hub. The function of the hub is similar with the access node but they work in different environment. We cannot use the same mechanism for both of them. In this work, we propose a new mechanism, which is based on the mechanism CUM used for the access node, for the hub and the impact of the proposed mechanism is observed on the performance of end-to-end connection.