Reduced banyan-type multiplane rearrangeable switching networks

The new concept of the multiplane rearrangeable switching network is presented. The new switching network's architecture is based on the well-known baseline network (the log₂(N, 0, 1) switching network). This new architecture can easily be obtained from the baseline network by the removal of some switching elements. It is therefore called the reduced baseline switching network and is denoted by log^r ₂((N, 0, 1). The new multiplane rearrangeable reduced baseline switching network requires fewer switching elements and crosspoints than the multiplane switching network which is based on the plain baseline network.     

Rearrangeable one-sided switching networks composed of uniform time-space elements

One-sided rearrangeable switching networks composed of uniform time-space elements are considered. Two theorems presenting conditions under which two- and four-wire networks are rearrangeable are given and proven. These theorems are also applicable for multiple-linkage space-division switching networks.     

Logically rearrangeable multihop lightwave networks

The optimization problem of rearrangeable multihop lightwave networks is considered. The authors formulate the flow and wavelength assignment problem, when minimizing the maximum flow in the network, as a mixed integer optimization problem subject to linear constraints. The problem is decomposed into two independent subproblems, the wavelength assignment (or connectivity problem) and the flow assignment (or routing problem). A simple heuristic provides a meaningful formulation to the connectivity problem, in a form similar to a transportation problem. An algorithm is then proposed which finds a heuristic initial logical connectivity diagram and the corresponding routing, and then iterates from that solution by applying branch-exchange operations to the connectivity diagram. The algorithm was tested on illustrative traffic matrices for an 8 node network with two transmitters and two receivers per node, and an improvement in achievable throughput over the Perfect Shuffle interconnection pattern was shown in all cases     

Wavelength rearrangeable and strictly nonblocking networks

The concept of rearrangeably and strictly nonblocking space division networks is extended to the wavelength dimension, resulting in a new family of interconnection network called wavelength-space division switches (WSDS). The complexity and wavelength assignment in these networks are discussed with some examples.<>     

A general class of rearrangeable interconnection networks

A class of rearrangeable interconnection networks which includes the Benes network as a special case is identified. An instance of this class consists of a set of parallel planes each consisting of a Delta network with a suitable number of additional stages. A formal definition is given and a rearrangeability condition is proven which gives a tradeoff between the number of planes and additional stages necessary     

New structure of one-sided switching network

A new structure of a one-sided digital switching network composed of triangular switches is proposed. In this structure some triangular switches operate as two-sided ones. The proposed network contains fewer elements than those previously known     

Design of photonic rearrangeable networks with zero first-orderswitching-element-crosstalk

The development of optical cross-connect architectures is a very important topic today. We consider here in particular the class of optical space-division switching fabrics configured as multistage structures built with 2×2 optical switching elements (SEs) and derived from a combination of vertical replication and horizontal expansion of Banyan networks. We determine the necessary and sufficient conditions for these matrices to be rearrangeably nonblocking and free of first-order crosstalk in SEs. This impairment is one of the major limitations in optical cross-connect performance. We focus on rearrangeable matrices since they have lower complexity than their strict-sense nonblocking counterparts. Given the current high cost of optical SEs, the rearrangeable solution looks attractive today     

A new decomposition algorithm for rearrangeable Closinterconnection networks

We give a new decomposition algorithm to route a rearrangeable three-stage Clos network in O(nr²) time, which is faster than all existing decomposition algorithms. By performing a row-wise matrix decomposition, this algorithm routes all possible permutations, thus overcoming the limitation on realizable permutations exhibited by many other routing algorithms. This algorithm is extended to the fault tolerant Clos network which has extra switches in each stage, where it provides fault tolerance under faulty conditions and reduces routing time under submaximal fault conditions     

Analytical and simulation study of simple rearrangeable multiexchange networks

Congestion probabilities for calls in simple three-exchange networks operated with and without rearrangements are determined analytically and by digital simulation. Load-loss curves are obtained, from which the gain in traffic capacity due to rearrangement and degradation due to overload can be found. It is concluded that routing control with rearrangements possesses a potential traffic-handling advantage over conventional automatic alternative routing.     

Strictly nonblocking three-stage Clos networks with some rearrangeable multicast capability

F.K. Hwang and S.C. Liaw (see IEEE/ACM Trans. Networking, vol.8, p.535-9, 2000) introduced a new nonblocking requirement for 2-cast traffic which imposes different requirements on different types of coexisting calls. The requirement is strictly nonblocking for point-to-point calls among the 2-cast traffic, and is rearrangeable for genuine 2-cast calls. We generalize the 2-cast calls to multicast calls and give a sufficient condition for such networks when the number of multicast calls is upper bounded.     

Multicast nonblocking switching networks

This paper considers three-stage switching networks for which nonblocking conditions with point-to-point traffic are given by the well known Clos (1953) theorem, under the assumption of absence of any optimized routing of the connections inside the network. We give the conditions for such a network to be strict-sense nonblocking under multicast traffic, by showing also that previously published papers, although claiming the same result, only provided sufficient conditions.     

Single sided switching networks

A novel and simple architecture for realising single-sided, rearrangeably-nonblocking, N-port switching networks (N is a power of 2), that uses N/2 log (N/2) elements, together with an efficient routing algorithm with time complexity O(N log (N)) is presented. The networks also exhibit a useful measure of fault tolerance.<>     

Neural networks for switching

The author argues that a strong impetus for using neural networks is that they provide a framework for designing massively parallel machines. He notes that the highly interconnected architecture of switching networks suggests similarities to neural networks. He presents two switching applications in which neural networks can solve the problems efficiently. He shows that a computational advantage can be gained by using nonuniform time delays in the network     

Tree-type photonic switching networks

The enormous bandwidth offered by optical systems makes photonic switching a very attractive solution for broadband communications. Tree-type architectures play an important role in the design of photonic switching networks. The authors present and discuss all known tree-type space-division photonic switching networks architectures in a unified framework, and propose a number of new solutions. The discussed networks can be implemented with guided-wave-based switching elements, or laser diodes and passive splitters and combiners. The following network types are considered: conventional, simplified, and two-active stage networks. Techniques for improving SNR as well as waveguide crossover minimization are presented and discussed     

Reliable digital switching networks

A method for the design of economic and reliable PCM switching networks composed of uniform time-space elements is proposed. The described networks can be used in switching systems containing concentrators connected by an even number of PCM links to a main switching network.     

Optically interconnected switching networks

Work on hybrid multistage switching networks is presented. A simple mapping rule is used to form a network using two-dimensional perfect shuffle interconnections, and other 2-D patterns are developed from other mappings. The general conditions for a 1-D net to be mappable into two dimensions are established, and it is pointed out that in practice all multistage interconnection networks (MINs) are mappable-a suitable mapping transformation is what is required. It is shown how to use the mapping process to produce hybrid MINs with a variable electronic island size. It is concluded that the design flexibility exists to take multistage processors and transform them into formats which are highly suitable for the employment of optical interconnects     

多粒度光突发交换网络目

高丢弃率一直是制约光突发交换(OBS:Optical Burst Switching)发展的关键因素,在OBS中引入双向预约机制是降低突发丢弃的有效方法.文章以OBS网络架构为基础,将波带交换与OBS相结合,提出交换粒度覆盖波带/波长/突发的多粒度光突发交换网络,以求在有效降低突发竞争的同时,提高网络的传输效率,增强OBS网络的实用性.     

Hybrid switching and p-routing for optical burst switching networks

One promising switching technology for wavelength-division multiplexing optical networks is optical burst switching (OBS). However, there are major deficiencies of OBS. (1) The delay offset between a control message and its corresponding data burst is based on the diameter of a network. This affects network efficiency, quality-of-service, and network scalability.( 2) OBS adopts one-way resource reservation scheme, which causes frequent burst collision and, thus, burst loss. We address the above two important issues in OBS. In particular, we study how to improve the performance of delay and loss in OBS. To reduce the end-to-end delay, we propose a hybrid switching scheme. The hybrid switching is a combination of lightpath switching and OBS switching. A virtual topology design algorithm based on simulated annealing to minimize the longest shortest path through the virtual topology is presented. To minimize burst collision and loss, we propose a new routing algorithm, namely, p-routing, for OBS network. The p-routing is based on the wavelength available probability. A path that has higher available probability is less likely to drop bursts due to collision. The probability-based p-routing can reduce the volatility, randomness, and uncertainty of one-way resource reservation. Our studies show that hybrid switching and p-routing are complementary and both can dramatically improve the performance of OBS networks.     

Designing multiprotocol label switching networks

Multiprotocol label switching adds to the capabilities of IP networks in several ways. Despite new capabilities, MPLS technology has much in common with ordinary IP networks. In turn, the design process for MPLS networks has much in common with the design of any IP network. This article examines MPLS and IP technology with particular emphasis on what is common between them. The common design steps of MPLS networks and other IP networks are outlined briefly, and those issues specific to MPLS networks are covered in more detail. This article emphasizes MPLS point of presence design, routing design issues for MPLS, and provisioning of sufficient label space     

Waveband switching in optical networks

The rapid advances in dense wavelength-division multiplexing technology with hundreds of wavelengths per fiber and worldwide fiber deployment have brought about a tremendous increase in the size (i.e., number of ports) of photonic cross-connects, as well as in the cost and difficulty associated with controlling such large cross-connects. Waveband switching (WBS) has attracted attention for its practical importance in reducing the port count, associated control complexity, and cost of photonic cross-connects. We show that WBS is different from traditional wavelength routing, and thus techniques developed for wavelength-routed networks (including, for example, those for traffic grooming) cannot be directly applied to effectively address WBS-related problems. We describe two multigranular OXC architectures for WBS. By using the multilayer MG-OXC in conjunction with intelligent WBS algorithms for both static and dynamic traffic, we show that one can achieve considerable savings in the port count. We also present various WBS schemes and lightpath grouping strategies, and discuss issues related to waveband conversion and failure recovery in WBS networks.