Fiber Routing, Wavelength Assignment and Multiplexing DWDM-Centric Converged Metro/Aggregation Networks

For the last few decades, fiber optic cables not only replaced copper cables but also made drastic evolution in the technology to overcome the optoelectronic bandwidth mismatch. Light trail concept is such an attempt to minimize the optoelectronic bandwidth gap between actual WDM bandwidth and end user access bandwidth. A light trail is an optical bus that connects two nodes of an all optical WDM network. In this paper, we studied the concept of split light trail and proposed an algorithm namely Static Multi-Hop Split Light Trail Assignment (SMSLTA), which aims to minimize blocking probability, the number of static split light trails assigned and also the number of network resources used, at the same time maximizing the network throughput. Our proposed algorithm works competently with the existing algorithms and generates better performance in polynomial time complexity.

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The Traffic Grooming Problem in Optical Networks with Respect to ADMs and OADMs: Complexity and Approximation

Algorithms ◽

10.3390/a14050151 ◽

2021 ◽

Vol 14 (5) ◽

pp. 151

Author(s):

Michele Flammini ◽

Gianpiero Monaco ◽

Luca Moscardelli ◽

Mordechai Shalom ◽

Shmuel Zaks

Keyword(s):

Cost Function ◽

Optical Networks ◽

Cost Minimization ◽

Convex Combination ◽

Optical Network ◽

Switching Cost ◽

Wavelength Assignment ◽

Intermediate Node ◽

Polynomial Time Approximation Algorithm ◽

Path Topology

All-optical networks transmit messages along lightpaths in which the signal is transmitted using the same wavelength in all the relevant links. We consider the problem of switching cost minimization in these networks. Specifically, the input to the problem under consideration is an optical network modeled by a graph G, a set of lightpaths modeled by paths on G, and an integer g termed the grooming factor. One has to assign a wavelength (modeled by a color) to every lightpath, so that every edge of the graph is used by at most g paths of the same color. A lightpath operating at some wavelength λ uses one Add/Drop multiplexer (ADM) at both endpoints and one Optical Add/Drop multiplexer (OADM) at every intermediate node, all operating at a wavelength of λ. Two lightpaths, both operating at the same wavelength λ, share the ADMs and OADMs in their common nodes. Therefore, the total switching cost due to the usage of ADMs and OADMs depends on the wavelength assignment. We consider networks of ring and path topology and a cost function that is a convex combination α·|OADMs|+(1−α)|ADMs| of the number of ADMs and the number of OADMs deployed in the network. We showed that the problem of minimizing this cost function is NP-complete for every convex combination, even in a path topology network with g=2. On the positive side, we present a polynomial-time approximation algorithm for the problem.

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A controlled deflection routing and wavelength assignment based scheme in Optical Burst Switched (OBS) networks

Journal of Optical Communications ◽

10.1515/joc-2019-0017 ◽

2020 ◽

Vol 0 (0) ◽

Author(s):

Bakhe Nleya ◽

Philani Khumalo ◽

Andrew Mutsvangwa

Keyword(s):

Wavelength Conversion ◽

Wavelength Assignment ◽

Wavelength Converters ◽

Core Network ◽

Least Cost Path ◽

Deflection Routing ◽

Backbone Networks ◽

The Core ◽

Optical Burst

AbstractHeterogeneous IoT-enabled networks generally accommodate both jitter tolerant and intolerant traffic. Optical Burst Switched (OBS) backbone networks handle the resultant volumes of such traffic by transmitting it in huge size chunks called bursts. Because of the lack of or limited buffering capabilities within the core network, burst contentions may frequently occur and thus affect overall supportable quality of service (QoS). Burst contention(s) in the core network is generally characterized by frequent burst losses as well as differential delays especially when traffic levels surge. Burst contention can be resolved in the core network by way of partial buffering using fiber delay lines (FDLs), wavelength conversion using wavelength converters (WCs) or deflection routing. In this paper, we assume that burst contention is resolved by way of deflecting contending bursts to other less congested paths even though this may lead to differential delays incurred by bursts as they traverse the network. This will contribute to undesirable jitter that may ultimately compromise overall QoS. Noting that jitter is mostly caused by deflection routing which itself is a result of poor wavelength and routing assigning, the paper proposes a controlled deflection routing (CDR) and wavelength assignment based scheme that allows the deflection of bursts to alternate paths only after controller buffer preset thresholds are surpassed. In this way, bursts (or burst fragments) intended for a common destination are always most likely to be routed on the same or least cost path end-to-end. We describe the scheme as well as compare its performance to other existing approaches. Overall, both analytical and simulation results show that the proposed scheme does lower both congestion (on deflection routes) as well as jitter, thus also improving throughput as well as avoiding congestion on deflection paths.

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A Shared Path Protection Mechanism Based on Delay Constraint in the Optical Network

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.427-429.2237 ◽

2013 ◽

Vol 427-429 ◽

pp. 2237-2244

Author(s):

Jie Li ◽

Xing Wei Wang ◽

Min Huang

Keyword(s):

Real Time ◽

Optical Network ◽

Propagation Delay ◽

Wavelength Assignment ◽

Delay Constraint ◽

Protection Mechanism ◽

Path Protection ◽

Important Concern ◽

Efficient Protection ◽

Shared Path Protection

Survivability is an important concern in the optical network. In order to offer an effective and efficient protection mechanism that meeting both delay constraint and availability guarantees for real-time services in the optical network, a shared path protection mechanism based on delay constraint is proposed in this paper. Thinking of the processing delay and the propagation delay as main factors which have great effect on the delay of real-time services, the mechanism designs the routing and wavelength assignment schemes for the working path and the protection path. Simulation results show that the proposed mechanism is both feasible and effective.

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