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Internet Service Providers (ISP) need to support Quality-of-Service (QoS) constrains in Internet multicast applications which are often delay-sensitive and demanding on network resources. This paper proposes a QoS-constraint multicast restoration scheme in WDM mesh networks based on 2-tuple domination core node selection algorithm which minimization of total network resources in "hop-count" as metric while meeting the "delay-constraint" as a second metric. The primary aim of this work is to provide fast inter- and intra-domain routings and steady local survivability with QoS-constraints based on the information obtained from the core nodes. Our simulation results show that the proposed algorithm outperforms the Dual Tree and MRLR algorithms in terms of the minimum restoration time needed for all recovery paths, blocking probability based on the minimum restoration time, instead of minimum hop count in our previous study [1], for different network topologies.

This study proposes a novel cost-based fault-tolerant WDM-EPON (CFT-WDM-EPON) to provide overall protection. It only equips a backup feeder fiber to recover the system failure. Additionally, a prediction-based fair wavelength and bandwidth allocation (PFWBA) scheme is proposed to enhance the differentiated services for WDM-EPON based on dynamic wavelength allocation (DWA) and prediction-based fair excessive bandwidth reallocation (PFEBR) from our previous work. PFEBR involves an early-DBA mechanism, which improves prediction accuracy by delaying report messages of unstable traffic optical network units (ONUs), and assigns linear estimation credit to predict the arrival of traffic during waiting time. DWA can operate in coordination with an unstable degree list to allocate the available time of wavelength precisely. Simulation results show that the proposed PFWBA scheme outperforms WDM IPACT-ST and DWBA3 in terms of packet delay, jitter performance, throughput, wasted bandwidth, gain ratio of bandwidth, and packet loss.

In the EPON, any failure of optical line terminal (OLT) or feeder fiber can halt the entire system. Many previous studies proposed dedicated protection architectures to protect the critical components, which results in high cost for deployment. To achieve high reliability and low-cost for deployment, this article proposes a novel fault-tolerant Multi-EPON system with cost-effective shared protection through Bridge ONUs. Under failures, the Bridge ONU controls the faulty EPON, plays the role of OLT and the transmission of faulty EPONs are restored by relaying to other interconnected adjacent EPONs. The minimum hop-count relay algorithm and the relay window mechanism are also proposed for the Multi-EPON system to efficiently help data relaying to the central office (CO). Furthermore, the one-wait dynamic bandwidth allocation enables the controller of affected Passive Optical Networks (PONs) to obtain more up-to-date buffer information from each ONU in order to enhance overall system performance. The simulation results show that the proposed Multi-EPON system can provide high system performance for different failure situations in terms of throughput, average delay, maximum delay, and expedited forwarding (EF) jitter, especially in high traffic loads.

Optical burst switching (OBS) networks have been receiving much attention as a promising approach to build the next generation optical Internet. In the bufferless DWDM switching technology, burst loss that should be minimized is the key design parameter. One of the critical design issues in OBS network is how to plan the optimal routing path in order to minimize burst dropping due to network resource contention. This study proposes the burst frequent-pattern tree (BFP-Tree) approach to pre-determine a suitable routing path in the OBS network. The BFP-Tree approach essentially is a learning-based mechanism that is able to determine a suitable transmission path from the historical network transaction data. The experiment results show that the successful rates of routing paths obtained by the BFP-Tree approach are able to converge to those of the optimal results.

In this paper, we propose a novel early dynamic bandwidth allocation (E-DBA) mechanism incorporated with a prediction-based fair excessive bandwidth reallocation (PFEBR) scheme in EPON. The E-DBA mechanism not only can reduce the idle period in the traditional DBA mechanism, but also provide more accurate prediction for the PFEBR scheme to ensure the fairness of all ONUs and improve the overall system performance. The proposed prediction model for different traffic classes is based on the variation of traffic for all ONUs in EPON. The simulation results show that the proposed E-DBA mechanism with PFEBR scheme can improve the system performance of well-known DBA algorithms.

This work describes a novel distributed algorithm, called the Cluster Allocation Algorithm (CAA), for the restoration scheme in a WDM mesh network. The nodes search for neighboring nodes and establish the relationship between them to build numerous logical clusters. Each cluster has a unique manager, called Cluster Head (CH) that searches for routing path, wavelength assignment (RWA) and restoration paths upon receiving requests from its cluster members. Some clusters might comprise only one CH, and cluster members in each cluster can be directly connected to CH. The communication among clusters is also negotiated through the manager. The selected restoration path is pre-computed from the CH to the destination node with the minimum cost function. Therefore, restoration paths can be sought with quick assignment of wavelength routings when the link, node or channel failure occurs based on the status of traffic load, number of nodes and transmission time. The primary aim of this work is to use clusters near faults to share the restoration load throughout the mesh network. The system performance of the CAA is compared with p-cycle, double cycle and DMRA methodologies in terms of restoration time and non-restoration ratio.

The integrated architecture of complementary Ethernet Passive Optical Network (EPON) and Worldwide Interoperability for Microwave Access (WiMAX) technologies combine the benefits of optical fiber capacity and wireless network mobility, which will become one of the promising broadband access technologies for next-generation network. In this paper, we propose a novel hybrid dynamic bandwidth allocation (DBA) and scheduling scheme for the integrated EPON and WiMAX in the access network to support quality of service (QoS) and class of service (CoS). The simulation results demonstrate that the proposed scheduling scheme enhanced performance in terms of drop probability, average queue length and average end-to-end packet delay, respectively.

Ethernet Passive Optical Network (EPON) is proposed as a simple, cost-effective and scalable solution for bandwidth bottlenecks in access networks which can enhance the system performance because it transmits the aggregated high-speed traffic from hundreds of subscribers. Dynamic Bandwidth Allocation (DBA) mechanism has not yet been seriously considered for use in star-ring EPON architecture. In this paper, a distributed QoS-based dynamic bandwidth allocation (DQ-DBA) scheduling mechanism for the star-ring-based EPON architecture including optical line terminal (OLT), Sub-OLT and ONUs has been proposed to improve the system performance of traditional tree-based EPON architecture. In DQ-DBA, the highest-priority traffic of each ONU is directed to the OLT by the tree structure; moreover, the lower-priority traffic on each ONU is transmitted to the Sub-OLT by ring architecture. This approach can effectively resolve the idle period problem and reduce the overloading of OLT in conventional DBA mechanisms. Exhaustive simulation experiments are performed to compare the system performance between the tree and the star-ring architectures and validate the effectiveness of the proposed mechanism. Simulation results show that the proposed DQ-DBA mechanism in star-ring architecture can reduce packet delay and jitter for the high-priority traffic, thus ensuring the quality of service (QoS) regardless of subscriber numbers.

Ethernet Passive Optical Networks (EPONs) are designed to deliver multiple services and applications, such as voice communications, standard (SDTV) and high-definition video (HDTV). To support these applications and their various requirements, EPONs require Quality-of-Service (QoS) mechanisms to be built in service. For this purpose, a scalable Interleaved Dynamic Bandwidth Allocation (IDBA) mechanism for sharing the uplink bandwidth among optical network units (ONUs) is proposed in this paper. The modus operandi of IDBA is to divide the cycle time by partitioning the ONUs into two groups with some timing overlap to execute interleaved bandwidth allocation, which cooperates with Limited Bandwidth Allocation (LBA), Excess Bandwidth Reallocation (EBR) and accurate prediction mechanism in EPONs. The proposed IDBA mechanism has two advantages, namely it eliminates the idle period problem in the traditional DBA mechanism, and guarantees QoS services by dynamically adjusting the bandwidth within the group of subscribers. This will not only support the differentiated services architecture but also offer various QoS levels. Simulation results obtained show that the proposed IDBA mechanism achieves desirable system performance relative to packet delay, jitter performance, throughput, ratio of packet loss and fairness.

Ethernet Passive Optical Network (EPON) was proposed to overcome the bandwidth bottleneck at the Access Networks due to its simplicity, cost effectiveness and wide spread deployment. The architecture in access networks can affect the system performance, because access networks transmit aggregated high-speed traffic from hundreds of subscribers. Dynamic bandwidth allocation (DBA) mechanisms have been applied in backbone networks, but are not considered significantly in the scope of star-ring architecture. In this paper, we propose a distributed QoS-Based Dynamic Bandwidth Allocation (DQ-DBA) scheduling for a modified star-ring-based EPON architecture. The modified star-ring architecture includes OLT, Sub-OLT (an intermediary between OLT and ONUs) and ONUs. The DQ-DBA is making the highest priority traffic (EF) of each ONU is sent to OLT by tree structure, and the minor priority traffic (AF and BE) of each ONU are transmitted to Sub-OLT by ring architecture. Furthermore, this approach can effectively resolve the idle period problem and reduce overload of OLT in traditional DBA mechanism. We perform exhaustive simulation experiments to study the system performance between tree architecture and star-ring architecture to validate the usefulness of the proposed mechanism. The simulation results show that the proposed DQ-DBA mechanism in modified star-ring architecture can reduce the packet delay and packet delay variation for high priority ONUs to ensure Quality of Service (QoS).

In this paper, a distributed Dynamic Bandwidth Allocation (D-DBA) scheduling mechanism for star-ring protection architecture is proposed in Ethernet Passive Optical Networks (EPONs). The D-DBA mechanism can effectively resolve the idle period problem and reduce overload of OLT in traditional DBA mechanism. We perform exhaustive simulation experiments to study the performance and validate the usefulness of the proposed mechanism. The simulation results show that the proposed D-DBA mechanism can reduce the packet delay and packet delay variation for high priority ONUs to ensure Quality of Service (QoS).

This study proposes a novel fault-tolerant architecture in WDM-EPON, Cost-based Fault-tolerant WDM-EPON (CFT-WDM-EPON), to provide overall protection. The CFT-WDM-EPON only equips a backup feeder fiber to recover the system failure. Additionally, a prediction-based fair wavelength and bandwidth allocation (PFWBA) scheme is also proposed to enhance the differentiated services for WDM-EPON based on the Dynamic Wavelength Allocation (DWA) and Prediction-based Fair Excessive Bandwidth Reallocation (PFEBR). The PFEBR involves an Early-DBA mechanism, which improves prediction accuracy by delaying report messages of unstable traffic ONUs, and assigns linear estimation credit to predict the arrival of traffic during waiting time. The DWA can operate in coordination with an unstable degree list to allocate the available time of wavelength precisely. Simulation results show that the proposed PFWBA scheme outperforms the WDM IPACT-ST with a single polling table and the Dynamic wavelength and bandwidth 3 (DWBA3) in terms of end-to-end delay and jitter performance.

In the EPON, many previous studies proposed dedicated protection architectures to protect the critical components which results in high cost for deployment. To achieve high reliability and low-cost for deployment, this article proposes a novel fault-tolerant Multi-EPON system with cost-effective shared protection scheme. Under the failures, the Bridge ONU controls the faulty EPON, plays the role of OLT and the transmission of faulty EPONs is restored by relaying to other interconnected adjacent EPONs. The minimum hop count relay algorithm and the relay window mechanism are also proposed in this article to help the data for relaying efficiently. Furthermore, the One-Wait DBA enables the controller of affected PONs to obtain more up-to-date buffer information from each ONU in order to enhance overall system performance. Simulation results show that the proposed Multi-EPON system can provide high system performance for different failed situations in terms of average delay, MAX delay and EF jitter, especially in high traffic loads.

A novel ring-based local fault recovery mechanism, multiple rings-based local restoration (MRLR), for one-point to multi-point multicast traffic based on the minimum spanning tree (MST) in WDM mesh networks is proposed in this paper. The MRLR mechanism dismembers the multicast tree into several disjoint segment-blocks (sub-trees) and reserves preplanned spare capacity to set up multiple protection rings in each segment-block for providing rapid local recovery. The MRLR scheme outperforms other methodologies in terms of the blocking probability, recovery time and average hop count of protection path per session for different network topologies.

This investigation examines all-optical multicast routing in wavelength-routed optical networks with sparse Multicast Capable (MC) nodes that have three phases. The first phase is the MC node placement, and the maximum path count first (MPCF) algorithm is utilized to obtain candidates for MC nodes. The second phase is a multicast routing with MC-based schemes which including two algorithms, namely, the Pre-computing Minimum Cost Tree (PMC) and Pre-computing Shortest Path Tree (PSP) algorithms. Both algorithms use Steiner tree and shortest path tree to create an MC-based tree. The third phase is the system maintenance. System performance of PMC and PSP is compared with that of the Route to Source (RTS) algorithm in terms of average number of wavelengths needed、average call blocking probability and mean maximum transmission delay. Simulation results indicate that the proposed schemes utilize the minimum number of wavelengths needed and reduce blocking probability.