A main issue for the realization of Optical Packet Switched (OPS) networks is the resolution of packet contention due to the lack of RAM-like optical buffer. Although an optical buffer using Fiber Delay Line (FDL) has been proposed as alternative, its capacity is extremely limited. For this reason, several studies have been challenged on this problem. One approach is a deflection routing. It is widely used in electronic packet switched networks or optical burst switched (OBS) networks. However, in the OPS networks, packet length is short, thus, speed limitation for route look-up is significantly stringent. If the network topology is geometric such as a Manhattan Street Network (MSN), a hop-by-hop routing can be implemented by simple optical logic devices without an electronic routing table, but if the topology is non-geometric, it is hard to implement the deflection routing electronically or optically. Another approach is a reflection routing. It is easy to implement, but its packet loss probability is inferior to that of the deflection routing. In this paper, we propose a packet contention resolution scheme that is based on the reflection routing and furthermore enables to detour the reflected packet to alternate path if its primary path is under congestion. Our method enables to alleviate the time limitation for alternate path setting by using the packet reflection latency and to improve the performance of packet loss probability. We evaluate the performance of the proposed method to confirm its effectiveness.
Recently, Optical WDM technology is introduced into backbone networks. On the other hand, as the future optical switching scheme, Optical Burst Switching (OBS) systems become a realistic solution. OBS systems do not consider buffering in intermediate nodes. Thus, it is an important issue to avoid overlapping wavelength reservation between partially interfered paths. To solve this problem, so far, the wavelength assignment scheme which has priority management tables has been proposed. This method achieves the reduction of burst blocking probability. However, this priority management table requires huge memory space. In this paper, we propose a wavelength assignment algorithm that reduces both the number of priority management tables and burst blocking probability. To reduce priority management tables, we allocate and manage them for each link. To
reduce burst blocking probability, our method announces information about the change of their priorities to intermediate nodes. We evaluate its performance in terms of the burst blocking probability and the reduction rate of priority management tables.
Recently, further high-speed and larger capacity communication is requested in the IP network. And multilayer network that constructs the IP network on an optical network such as IP over WDM is focused on. Under such a network environment, the multipath routing for setting two or more paths between a starting and ending nodes in each network is researched. The multipaths are taken advantage of load balance and path recovery and damaged traffic is switched to other paths at the starting node if a failure happens on a path. However, the traditional routing often finds multipaths overlapping on some links and nodes because of its low "disjoint property". Hence, path recovery is difficult because the multipaths may be interrupted at the same time. In order to resolve the problem in multilayer network, we propose the local path configuration method considering global path optimality. Concretely, we propose a network architecture where networks are connected by multiple edge nodes and multipath routing method with new link cost and parallel calculation of multipaths. As a result, the multipaths are prevented from overlapping and the disjointed multipaths enable efficient path recovery in case of a failure. Moreover, we verify the effectiveness of the disjoint property.
Increasing the capacity and intelligence of the next-generation Internet requires the application of optical technologies to switching nodes as well as transmission lines, and the development of advanced network architectures with end-to-end connection setup processing at the source node and autonomous routing at intermediate nodes. In this paper, one configuration of a photonic IP switching network is presented, where a set of multiple encoding CDM codes is utilized as routing information. Also, the node configurations of this network are proposed. In addition, we show characteristics between the BER and the number of nodes in each layer of the network.
Conference Committee Involvement (1)
Network Architecture, Management, and Applications IV
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