Routing and Spectrum Allocation in Elastic Optical Networks: A Tutorial

Abstract

Flexgrid technology is now considered to be a promising solution for future high-speed network design. In this context, we need a tutorial that covers the key aspects of elastic optical networks. This tutorial paper starts with a brief introduction of the elastic optical network and its unique characteristics. The paper then moves to the architecture of the elastic optical network and its operation principle. To complete the discussion of network architecture, this paper focuses on the different node architectures, and compares their performance in terms of scalability and flexibility. Thereafter, this paper reviews and classifies routing and spectrum allocation (RSA) approaches including their pros and cons. Furthermore, various aspects, namely -fragmentation, modulation, quality-of-transmission, traffic grooming, survivability, energy saving, and networking cost related to RSA, are presented. Finally, the paper explores the experimental demonstrations that have tested the functionality of the elastic optical network, and follows that with the research challenges and open issues posed by flexible networks.Index Terms-Elastic optical networks, node architecture, spectrum management, routing and spectrum allocation, and sliceable bandwidth-variable transponder.

Optimized traffic profile for FlexGrid optical networks

“…As for the time complexity analysis, two contributions, stemming from, respectively, routing and spectrum allocation are taken into account. As the shortest path is calculated adaptively (up to three trials in case there is blocking), and as explained in reference [9] Elastic (1 to 10 FS) connections are generated.…”

“…In addition, the entire bandwidth of the connections must be contiguously allocated, also referred as the spectrum contiguity constraint. The Routing and Spectrum Allocation (RSA) problem in FlexGrid optical networks has been widely studied, considering the static traffic case (network planning phase) as well as dynamic (in operation) network scenarios [3][4][5][6][7][8][9][10][11][12][13]. There, connection arrival and departure processes are random and the network has to accommodate incoming traffic in real time.…”

Who shot Optical Packet switching?

“…Addressing the emerging requirements for flexibility, scalability, resilience, and adaptability, the Architecture on Demand (AoD)-based Flex-OXC nodes was proposed. j) 2015, [10] -EON is a promising concept but its implementation remains some way off: One of the important challenges faced by the research community is to develop a new sliceable bandwidth-variable transponder, which supports sliceability, multiple bit rates, multiple modulation formats, and code rate adaptability. However, 100 Gb/s OFDM transponders can adapt to lower bit rates.…”

Approaches to maximize the open capacity of elastic optical networks

“…Recently, several authors [1]- [6] have pointed out that it is possible to increase the spectrum efficiency of WDM optical networks if a more elastic method of spectrum allocation is accomplished to make it "Gridless". The "Gridless" network architecture is called Elastic Optical Network (EON) in the literature and was originally proposed in [2], [3].…”