Data-centric networking using multiwavelength headers/labels in packet-over-WDM networks: A comparative study

In this paper, various issues related to packet transportation in dynamically reconfigurable networks are studied and techniques for transmitting the associated signaling are discussed. A novel transportation frame based on multisymbol coding is presented, its functionality is analyzed, and the various alternatives for transmitting multiwavelength label/headers are reviewed and benchmarked. A physical layer performance comparison between two multiwavelength schemes, i.e., the bit-parallel and the multilevel (M-ary) coded, is carried out using analytic modeling as well as simulation tools. It is shown that the multilevel coding is an interesting solution, particularly in a wide-area network environment deploying line rates higher than 10 Gb/s.     

Performance Constraint Analysis of WDM LANs with Nonzero Propagation Delays and Destination Conflicts

In this paper, we study the effect of the round trip propagation delay on performance measures of wavelength division multiplexing (WDM) networks. Even though the impact of propagation delay is substantial in the optical network's behavior, most of the studies ignore the effect of this time component in throughput and delay evaluation. We assume a WDM local area network (LAN) where the round trip propagation delay is less or equal to a data packet transmission time. The proposed asynchronous transmission policy avoids data channel collision. In the analysis, we take into account the propagation delays and the effect of receiver collision for a system with a finite number of stations.     

Design and Analysis of a Synchronous Transmission WDMA Protocol

In this paper, we propose a synchronous WDMA protocol for a passive star topology and suggest a new architecture for the network interface of each station. The multichannel nature of WDM networks involves receiver collision phenomena at the destination. We develop an analytical model based on a finite number of tunable receivers and a finite number of stations to investigate the performance of the proposed protocol. Numerical results are showing the performance behaviour for various number of channels, stations, and tunable receivers. Also simulation results are presented for comparison with the results obtained by the performance analysis.     

Improved Performance Analysis for Synchronous Single-Hope WDM Networks

This note extends the work in the paper [1] and presents a precise method without simplifications of the receiver collision analysis for the synchronous transmission protocols in the well known Passive Star WDM topology.     

A slotted access control protocol for metropolitan WDM ring networks

In this study we focus on the serious scalability problems that many access protocols for WDM ring networks introduce due to the use of a dedicated wavelength per access node for either transmission or reception. We propose an efficient slotted MAC protocol suitable for WDM ring metropolitan area networks. The proposed network architecture employs a separate wavelength for control information exchange prior to the data packet transmission. Each access node is equipped with a pair of tunable transceivers for data communication and a pair of fixed tuned transceivers for control information exchange. Also, each access node includes a set of fixed delay lines for synchronization reasons; to keep the data packets, while the control information is processed. An efficient access algorithm is applied to avoid both the data wavelengths and the receiver collisions. In our protocol, each access node is capable of transmitting and receiving over any of the data wavelengths, facing the scalability issues. Two different slot reuse schemes are assumed: the source and the destination stripping schemes. For both schemes, performance measures evaluation is provided via an analytic model. The analytical results are validated by a discrete event simulation model that uses Poisson traffic sources. Simulation results show that the proposed protocol manages efficient bandwidth utilization, especially under high load. Also, comparative simulation results prove that our protocol achieves significant performance improvement as compared with other WDMA protocols which restrict transmission over a dedicated data wavelength. Finally, performance measures evaluation is explored for diverse numbers of buffer size, access nodes and data wavelengths.     

Buffer analysis with finite number of tunable receivers in WDM passive star networks

This study develops a performance model as an expansion of the receiver collision analysis presented in [I.E. Pountourakis, Performance evaluation with receiver collisions analysis in very high-speed optical fiber local area networks using passive star topology, J. Lightwave Technol. 16 (12) (1998) 2303–2310] for WDM networks. By theoretical analysis we estimate the receiver collision phenomenon and evaluate the performance measures and the rejection probability at destination for finite number of tunable receivers. Receiver collision analysis makes the performance behavior more realistic and expands the original analysis.     

A channel reuse strategy with adaptive channel allocation for all-optical WDM networks

The fundamental problems of WDM networks are: (1) high rate of control packet loss and (2) high propagation delay for each (re)transmission. In this paper, we minimize the station randomness to access the control architecture introducing a collisions-free access scheme. We propose a synchronous protocol according which at the end of the propagation delay each station applies a distributed algorithm for packet transmission following the data channel collisions and the receiver collisions avoidance algorithms. We introduce two data transmission stages. The time difference between them is one packet transmission time. At the end of the first stage all data channels are free and can be reused by the remaining data packets during the second stage. The proposed protocol ensures a totally collisions-free performance. The main advantage is that the data channels reuse strategy applied during the second stage provides enhanced transmission probability to the rejected packets during the first stage. This allows the data packets to try retransmission in the same cycle without requiring control packets re-coordination that increases propagation delay. Thus, we achieve large number of data packets transmission, even more than the data channels number, providing throughput improvement and delay reduction, comparing with other studies.     

An input traffic allocation strategy and an efficient transmission technique for collisions-free WDM ring MANs

This paper presents a wavelength division multiplexing multi-ring architecture with a separate control wavelength for metropolitan area networks. We study the critical problem of low fiber bandwidth utilization that many access ring protocols introduce, especially at high load conditions. In our study this problem is effectively faced by: (1) applying an efficient slotted access algorithm to avoid both data wavelengths and receiver collisions, (2) introducing a number of buffers at each node to effectively allocate the incoming traffic into them, and (3) applying an efficient algorithm for buffer selection for transmission that combines the priority criteria of packet age and receiver collisions avoidance. In this way, we obtain maximum fiber bandwidth utilization. Especially, our aim is to achieve not only significant throughput enhancement, but also essential dropping probability and total delay reduction. Also, the number of transmission buffers per node is investigated in order to manage maximum throughput improvement, while considering the financial cost. Finally, a discrete-event simulation model based on Poisson statistics is developed for the performance measures evaluation.     

Slotted optical switching with pipelined two-way reservations

Optical burst switching is a core architecture designed to reconcile the available optical technology with the increasing burstiness of traffic. However, disappointing performance in terms of high packet loss and/or low system utilization discouraged broader experimental implementations. A method to avoid these losses by first sending over the control channel a short scout packet that simulates the events that the actual burst will experience is proposed in this paper. Once the scout message detects a drop at any intermediate node, it returns back to the source to avert the payload emission and repeat the process. The way the control works results in essential service quality features, i.e., no loss of bursts, no out-of-order emissions, increased efficiency, much reduced delay variation, and graceful throttling of the load respecting the contracted rates.     

Stability and throughput optimization of multichannel slotted non-persistent CSMA protocol

This paper describes two protocols suitable for a multichannel, multiaccess slotted non-persistent CSMA environment for infinite population, analyses their stability and examines their throughput optimization. The common sensing multichannel slotted non-persistent CSMA (CSCSMA) protocol is an extension of the slotted single channel non-persistent CSMA protocol with an appropriate policy for the selection of the channel in which a station (re)transmits. This policy restricts the control information among the stations, and consequently reduces the cost of the station interface. Pakes's Lemma criteria are applied to define sufficient conditions for ergodicity of the Markov chain, which describes the evolution of the busy station population, and to specify regions in which the multichannel system is stable. Control parameters are the retransmission probabilities. Optimization rules are derived which show that the optimal retransmission probabilities may be expressed as a function of the number of busy stations. The separate sensing multichannel slotted non-persistent CSMA protocol (SSCSMA), using a different policy, distinguishes the channels into two groups: the retransmission channel group devoted in collision resolution; and the transmission channel group for the access of free stations. Stability regions are defined using the results for CSCSMA, and rules for optimal allocation of channels among the two groups are derived for improvement of system performance.