Photonic Slot Routing Research Articles

Node architectures for aggregation of traffic from access networks

This article surveys and classifies recent prototypes of node architectures for dynamic traffic aggregation in all‐optical access‐core networks. These networks act as backbones for optical line terminators (OLT) or electronic switches that serve optical access networks. For reasons of economy they are typically constructed as unidirectional rings or busses. Well‐known optical time and wavelength division networks and hybrid versions following the photonic slot routing principle are introduced and compared. All of the architectures shown here perform some kind of carrier sensing to avoid collisions in a de‐centralized way. We give approximations of the expectable gain of dynamic channel sharing over static assignment and the tuning time penalty. Technological limitations and cost driving factors are analyzed with respect to a low‐cost implementation of a dynamic traffic aggregation.

Photonic slot routing in optical transport networks [Book Review

Photonic slot routing in optical transport networks [Book Review

Photonic slot routing: a cost effective approach to designing all-optical access and metro networks

In the backbone network, the high level of traffic aggregation achieved by numerous users is efficiently served by means of optical circuit switched solutions-the so-called wavelength routing approach. In the access and metro networks, on the contrary, the reduced level of traffic aggregation makes wavelength routing solutions inadequate. The finer and more dynamic bandwidth allocation provided by packet-interleaved optical time-division multiplexing is thus advocated in these network areas. This article presents a survey of an OTDM approach, known as photonic slot routing, or PSR. It is illustrated how this approach may provide a cost-effective solution to deploying all-optical access and metro networks with today's technology.

Capacity allocation and contention resolution in a photonic slot routing all-optical WDM mesh network

Photonic slot routing (PSR) has been proposed as an approach to implement an all-optical packet-switched network in a manner which is scalable and not overly complex. In PSR, packets are transmitted within a basic transport unit referred to as a photonic slot. The photonic slot is fixed in length and spans multiple wavelengths. Each photonic slot is routed through the network as a single entity; thus, individual wavelengths do not need to be multiplexed or demultiplexed at intermediate nodes through which the photonic slot is traversing. When implementing PSR in a mesh environment, a number of significant issues must be addressed. Two such issues are fairness and contention resolution. In this study, we propose a novel approach for allocating capacity on each link in a fair manner, and we investigate various approaches, such as buffering and deflection, for handling contention. We develop an analytical model to evaluate the performance of such networks, and validate the analysis through simulation. It is shown that the proposed capacity allocation approach can significantly reduce contention in the network and provide a fair allocation of bandwidth to each source-destination pair.

Scalable WDM access network architecture based on photonic slot routing

This paper introduces an approach to solving the fundamental scalability problem of all-optical packet switching wavelength-division multiplexing (WDM) access networks. Current optical networks cannot be scaled by simply adding nodes to existing systems due to the accumulation of insertion losses and/or the limited number of wavelengths. Scalability through bridging requires, on the other hand, the capability to switch packets among adjacent subnetworks on a wavelength basis. Such a solution is, however, not possible due to the unavailability of fast-switching wavelength sensitive devices. In this paper, we propose a scalable WDM access network architecture based on a recently proposed optical switching approach, termed photonic slot routing. According to this approach, entire slots, each carrying multiple packets (one on each wavelength) are "transparently" routed through the network as single units so that wavelength sensitive data flows can be handled using fast-switching wavelength nonsensitive devices based on proven technologies. The paper shows that the photonic slot routing technique can be successfully used to achieve statistical multiplexing of the optical bandwidth in the access network, thus providing a cost-effective solution to today's increasing bandwidth demand for data transmissions.

Slot Routing as a Solution for Optically Transparent Scalable WDM Wide Area Networks

All-optical Wavelength Division Multiplexing (WDM) backbones are believed to be a fundamental component in future high speed networks. Currently, the most pursued approach for Wide Area Networks (WANs) is wavelength routing, in which communication circuits are established between node pairs by means of lightpaths (paths of light) spanning one or more fiber-optic links. This approach has, however, two drawbacks. Since the number of wavelengths and links in a network is finite, not all node pairs can be connected via a dedicated lightpath directly. Consequently, some node pairs will communicate using a concatenation of lightpaths, which requires electronic switching of in transit information, loosing the advantages of optical transparency. Secondly, typically some form of (electronic) traffic grooming will be necessary to make efficient use of the fixed lightpath capacity. This paper proposes to design all-optical WANs using a novel approach, called photonic slot routing. With photonic slot routing, entire slots, each carrying multiple packets on distinct wavelengths, are switched transparently and individually, using available fast and wavelength non-sensitive devices. The advantage of using photonic slot routing is threefold. All node pairs in the network communicate all-optically. Traffic aggregation necessary to efficiently use the capacity of the wavelength channels is optically achieved. The solution is practical as it is based on proven optical technologies. In addition, through the use of wavelength non-sensitive devices the proposed WAN design yields intrinsic scalability in the number of wavelengths.

A fair slot routing solution for scalability in all-optical packet switched networks

181 Abstract. The concept of Photonic Slot Routing (PSR) was recently proposed by the authors for providing scalability in WDM packet switching networks. PSR circumvents the fundamental problem of complexity of extant optical technologies when trying to use fast, wavelength selective switches to obtain all-optical packet switching. In a PSR network, wavelength sensitive information (i.e., optical packets) is handled by simplified routers which make use of wavelength non-sensitive devices, based on proven technology, to switch a set of packets on distinct wavelengths as a single unit, termed the photonic slot. While leading to a practically simple router architecture, the all-optical PSR based network must also achieve a fair bandwidth allocation and deal with the contention that may arise at the router between photonic slots that arrive in different input fibers. The paper shows how the above objectives can be met by combining a fixed capacity assignment control with the PSR concept, thus achieving a bandwidth transparent, scalable and fair packet switching network with contention-free transmissions.