In this paper, we propose a novel QoS guaranteed algorithm for .4 standard provides a Guaranteed Time Slot (GTS) mechanism to allocate a specific duration within a superframe structure for time-critical transmissions. However, there are many weak points to support real-time applications. We suggest a new slot allocation algorithm that enables guaranteed services to be more efficient. The proposed algorithm also allocates a new guaranteed time slot dynamically to support real-time applications which have periodic messages. We evaluate the delay bounds and the throughput of the proposed scheme compared with original protocol. We then show that our proposal improves the bandwidth utilization and guarantees real-time features more strictly.

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In this paper, we discuss the issues of providing protection for point‐to‐multipoint connections in both Ethernet and MPLS‐TP‐based packet transport networks. We introduce two types of per‐leaf protection–linear and ring. Neither of the two types requires that modifications to existing standards be made. Their performances can be improved by a collective signal fail mechanism proposed in this paper. In addition, two schemes — tree protection and hybrid protection — are newly proposed to reduce the service recovery time when a single failure leads to multiple signal fail events, which in turn places a significant amount of processing burden upon a root node. The behavior of the tree protection protocol is designed with minimal modifications to existing standards. The hybrid protection scheme is devised to maximize the benefits of per‐leaf protection and tree protection. To observe how well each scheme achieves an efficient traffic recovery, we evaluate their performances using a test bed as well as computer simulation based on the formulae found in this paper.

We introduce an improved Ethernet ring protection method, selective filtering database (FDB) advertisement, to minimize traffic overshoot in the event of a failure or recovery. On the protection switching event, the proposed method makes all ring nodes perform an FDB flush except the FDB entries associated with their client subnets. Then, ring nodes rapidly exchange their client MAC address lists so that their FDBs are immediately updated by indirect MAC address learning. The proposed scheme guarantees fast and reliable protection switching over the standard scheme.

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Summary Shared mesh protection (SMP) protects service traffic on a working path and requires coordinated use of the shared resources on a protection path when the traffic is routed through the protection path. If there are many intermediate nodes on the protection path, the delay caused by the coordination at each node increases the protection switching time, resulting in losing more traffic. Considering the capacity of a link and the bandwidth required by the protection paths using that link, it appears that coordination is necessary. However, looking closely at the relationships with other links and their protection paths, there exist resources that may require no coordination at all. This observation leads to the fact that protection switching time can decrease when bypassing some intermediate nodes for coordination. This fact introduces an optimization problem, in which the objective is to exclude these resources as much as possible from the set of resources for which coordination is required. A sub‐problem is finding these excludable candidate resources. For both the main problem and the sub‐problem, which are NP‐hard, we propose a greedy algorithm and a branch‐and‐bound algorithm, respectively. The simulations show that the results using the proposed algorithms are near‐optimal. Furthermore, in an actual topology configured with the SMP environment, the protection switching time is improved by excluding resources for which coordination is not required, compared to the existing Optical Transport Network (OTN) SMP mechanism.