通信工程文献翻译——摘要--FlexGrid技术现在被认为是未来高速网络设计一个可行的解决方案。在这种情况下，我们需要一个涵盖了弹性光网络关键方面的综述。本综述开头简要介绍了弹性光网络及其独特特性。论文接着介绍了弹性光网络的架构及其工作原理。为了完成对网络架构的讨论，本文重点研究了不同的节点架构，并比较了它们在可扩展性和灵活性方面的性能。此后，本文回顾和分类路由频谱分配（RSA）方法，包括他们的优点和缺点。此外，还提出了与RSA相关的各个方面，即碎片，调制，传输质量，流量疏导，生存能力，节能和网络成本。最后，本文探讨了测试弹性光网络功能的实验示范，随之而来的是灵活网络带来的研究挑战和存在的问题。

关键词--弹性光网络，节点结构，频谱管理，路由和频谱分配，切片带宽可变转发器。

1 引言

全球通信的快速增长和互联网的迅速普及大大改变了我们的生活方式。这场革命导致了每年通信带宽的大幅增长。光网络有可能支持通信带宽的持续需求。以大容量密集波分复用（DWDM）为基础的光网络[ 1 ]，[ 2 ] 通过使用上层来将低速业务流聚合到流量梳导机制中的光路中[3] - [6] ]。骨干网中已经部署了单通道高达40 Gb / s的基于DWDM的系统，同时100 Gb / s接口现在已经可以在市场上销售，预计即将推出100Gb / s的部署。据TeleGeography [7]估计，2018年国际带宽需求将达到606.6 Tb / s，2020年将达到1,103.3 Tb / s。因此，在不久的将来[8]，[9]，光网络将需要支持Tb / s级传输。不幸的是，传统的光传输技术具有的扩展性能不足以满足不断增长的业务需求，因为它受到电带宽瓶颈的限制。随着传输速度的提高[10]，物理损伤越来越严重。此外，流量行为正在迅速变化，流量源的流动性越来越大，使得疏导更为复杂。因此，研究人员正在专注于高速光网络的新技术。

为满足未来互联网的需要，光传输和网络技术正在朝着提高效率、灵活性和可扩展性的目标迈进。最近，弹性光网络[ 11 ] - [ 15 ]已被证明是一种很有前途的未来高速光通信的候选者。弹性光网络可以根据客户的带宽需求分配频谱。频谱被分为窄的频隙，光连接器分配不同数量的频隙。其结果是，相比于以DWDM为基础的光网络，网络利用率大大提高。在弹性光网络中，固定在目前部署的网络中一定数量的传输参数，如光数据速率、调制格式和信道之间的波长间隔，将可调。鉴于未来的需求表明，需要用高速光连接来对数据传输进行优化，对于DWDM光网络，弹性光网络是一个合适的替代。

由于弹性光纤网络已被广泛接受作为下一代高速网络，研究人员已经重点研究了其架构、频......

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, sliceable bandwidth-variable transponder.

I. INTRODUCTION

THE rapid growth in world-wide communications and the rapid adoption of the Internet has significantly modified our way of life. This revolution has led to a vast growth in communication bandwidth in every year. An optical network has the potential to support the continued demands for communication bandwidth. The high capacity of dense wavelength division multiplexing (DWDM)-based optical networks [1], [2]is assisted by the use of upper layers to aggregate low-rate traffic flows into lightpaths in mechanism of traffic grooming [3]–[6]. DWDM-based systems with up to 40 Gb/s capacity per channel have been deployed in backbone networks, while 100 Gb/s interfaces are now commercially available,and 100 Gb/s deployment is expected soon. TeleGeography [7] expects that international bandwidth demands will be approximately 606.6 Tb/s in 2018 and 1,103.3 Tb/s in 2020.

Therefore, optical networks will be required to support Tb/s class transmission in the near future [8], [9]. Unfortunately,conventional optical transmission technology has inadequate scaling performance to meet the growing traffic demands as it suffers from the electrical bandwidth bottleneck limitation,and the physical impairments become more serious as the.......