Metropolitan ring networks are usually used to connect the high speed backbone networks with the high speed access networks. In this paper, we focus on the end-to-end performance of a multi-ring architecture in which metropolitan access networks (MANs) are interconnected by a metropolitan core network. These rings are synchronized and can be interconnected transparently through single access nodes (Hub node) or multiple access nodes. A multi ring architecture consisting of two slotted MAN rings connected by a ring-based slotted metro core will be simulated. The major problem in this architecture is how to resolve the synchronization shift between rings while assuring the traffic routed efficiently from the metro access to the metro core networks. To ensure this efficiency, we use some optical packet filling mechanisms such as Aggregation Mechanism, CUM (CoS-Upgrade Mechanism), DCUM (Dynamic CoS-Upgrade Mechanism). Through various simulations, we present some performance results in terms of jitter and mean end-to-end delay which show that the use of the pair of Aggregation/DCUM improves the transmission capability at Hub nodes as compared with others pairs and provide a cost-effective solution.