As multicast applications become more and more popular, implementing multicast in optical domain has attracted more
and more attention due to its more efficient bandwidth usage. The MC-OXC is the key for realizing multicasting at
optical layer and directly affects the performance of the multicast services in WDM networks. In this paper, a novel
mixed-integrated optical multicast switch for multicast-capable cross-connect is proposed. The new architecture uses
power splitters for multicast connections only, allowing unicast sessions to pass without enduring unnecessary power
loss. And also the performances of the MC-OXC are analyzed. We performed the cost and cost sensitivity analysis for
different MC-OXCs. The results show that the proposed architecture guarantees strictly nonblocking with lower costs.
As multicast applications become more and more popular, implementing multicast in optical domain has attracted more
and more attention due to its more efficient bandwidth usage. And also these services have Quality-of-Service (QoS)
requirement. In this paper, the problem of cost-effective optical multicast provisioning to satisfy the differentiated leaf
availability requirements is formally stated. A Mixed Integer Linear Program (MILP) formulation is proposed for
provisioning dedicated light-tree protection with differentiated leaf availability guaranteed. The algorithm is so complex
and infeasible that we also propose a feasible two-step approximate approach to solve the problem. Different from the
previous schemes, our scheme finds out the primary light-trees and backup paths for multicast sessions destination
nodes whose availability is not satisfied with the availability requirement. Because of taking the different leaf
availability requirements into account, the proposed algorithm finds out more efficient feasible solution requiring less
network resources.
Multicast applications have attracted more and more attention due to more efficient bandwidth usage and the increasing popularity of the point-multipoint multimedia applications. Optical multicasting outperforms the electronic multicasting in some aspects. Service level agreement (SLA) and quality of service (QoS) are important to service providers and users. Service providers always first maximize revenue to accept as many as connection requests as possible and then to minimize the capacity of all accepted connection. In this paper, the problem of cost-effective optical multicasting connection provisioning to satisfy the connections' availability requirements on a given physical topology is formally stated. We propose a mixed integer linear program (MILP) based approach for static multicast traffic. The feature of our algorithm lies on without considering any protection schemes, and when the system adapts dedicated protection or the sharing protection, the problem is more complicated.
Multicast protection strategies have been widely explored in current literature. However, the leaf availability requirements are not taken into account. In this paper, we investigated approaches and algorithms for establishing a multicast session with differentiated leaf availability requirements in WDM mesh network while protecting it against single link failure. An effcient and cost-effective heuristic is presented to solve the problem and is compared with two other schemes, one with no protection (Scheme I) and the other with dedicated protection (Scheme II). We also formulated a possible improvement of the proposed algorithm. Simulation results based
on 14 node NSFNET topology and comparisons among these schemes are also discussed. The performance of an algorithm is measured in terms of Average Cost and Average Satisfaction Ratio. The improved algorithm shows much better performance than the other ones, thus achieving the goal of effectively establishing protected multicast sessions with differentiated destination availability requirements. Finally, through numerical simulation results, we find that some links are critical to the performance of the network. Increasing the availability and capacity of these links will greatly enhance the network performance. This result is helpful to network planning
and design.
From element automatic control view, we propose a configuration algorithm for three-level cross-connects in data plane to handle with bypass, grooming and local add/drop traffic of fiber-level, band-level and wavelength-level by a abstract bipartite graph of MG-OXC and bandwidth utilization spectra graph. The configuration algorithm is evaluated by computer simulation as well as validated by experiment on our flexible Multi-functional Optical Switching Testbed (MOST).
Slotted WDM, which achieves higher capacity compared with conventional WDM and SDH networks, has been discussed a lot recently. The ring network for this architecture has been demonstrated experimentally. In slotted WDM ring network, each node is equipped with a wavelength-tunable transmitter and a fixed receiver and assigned with a specific wavelength. A node can send data to every other node by tuning wavelength accordingly in a time slot. One of the important issues for it is scheduling. Scheduling of it can be reduced to input queued switch when synchronization and propagation are solved and many schemes have been proposed to solve these two issues. However, it’s proved that scheduling of such a network taking both jitter and throughput into consideration is NP hard. Greedy algorithm has been proposed to solve it before. The main contribution of this paper lies in a novel genetic algorithm to obtain optimal or near optimal value of this specific NP hard problem. We devise problem specific chromosome codes, fitness function, crossover and mutation operations. Experimental results show that our GA provides better performances in terms of throughput and jitter than a greedy heuristic.
The increasing switching capacity brings the optical node with considerable complexity. Due to the limitation in cost and technology, an optical node is often designed with partial switching capability and partial resource sharing. It means that the node is of blocking to some extent, for example multi-granularity switching node, which in fact is a structure using pass wavelength to reduce the dimension of OXC, and partial sharing wavelength converter (WC) OXC. It is conceivable that these blocking nodes will have great effects on the problem of routing and wavelength assignment. Some previous works studied the blocking case, partial WC OXC, using complicated wavelength assignment algorithm. But the complexities of these schemes decide them to be not in practice in real networks. In this paper, we propose a new scheme based on the node blocking state advertisement to reduce the retry or rerouting probability and improve the efficiency of routing in the networks with blocking nodes. In the scheme, node blocking state are advertised to the other nodes in networks, which will be used for subsequent route calculation to find a path with lowest blocking probability. The performance of the scheme is evaluated using discrete event model in 14-node NSFNET, all the nodes of which employ a kind of partial sharing WC OXC structure. In the simulation, a simple First-Fit wavelength assignment algorithm is used. The simulation results demonstrate that the new scheme considerably reduces the retry or rerouting probability in routing process.
Open Shortest Path First (OSPF) protocol is used for the routing and topology discovery in the optical networks. In the next generation optical network, enhanced OSPF is extended to support opaque LSA. In optical networks, each OXC disseminates the resource information of the optical links that bundled between the adjacent neighbors. Recently proposed enhanced OSPF protocol is promising to reduce the blocking probability of the data plane at the cost the usage of the control channel bandwidth in the control plane. This article has a full analysis of the bandwidth usage due to the optical LSA updates. We also discuss the blocking probability with the enhanced OSPF, some key results on the performance of the enhance OSPF are also given in this article. Finally, we propose a method to balance the tradeoff of the flooding information and the blocking probability.
A novel method called data plane shared ring scheme (DPSRS) is proposed in IP over automatic switched transport networks (ASTN) overlay network. Based on the novel scheme, explicit analysis on related network architecture, edge node structure and operation process are made. For decision of bandwidth restriction parameters two algorithms are also proposed.
Multicast applications have attracted more and more attention due to more efficient bandwidth usage and the increasing popularity of the point-multipoint multimedia applications. Supporting multicast directly at physical layer, namely optical multicasting, can provide improved performance over electronic multicasting. In this paper, a new Mixed Integer Linear Programming algorithm is proposed to resolve the light-tree routing and wavelength assignment problem with wavelength continuity constraints. The node in our system is limited branching and power-efficient multicast capable OXC. The node constraints are considered in our model formulation. Numerical results are given by using representative examples and discussed to show the efficiency of our algorithm.
To solve the scalability and flexibility issue in current optical network testbeds, a Multi-functional Optical Switching Testbed (MOST) has been built. Benefiting from design of modular hardware and layered software, network experiments of scalability and complicated node architecture can be made based on it. The hardware and software structure of the MOST system is explicitly analyzed in the article and demonstrations of a 12-node ASON and shared wavelength conversion ASON on MOST are also reported.
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