| Since the 21st century, people's lives have gradually been ushered into the information age. Information technology has now taken a center stage in people's work and life. The use of the network has greatly enriched people's access to information. With the advent of the information age; the network has seen a rapid development. As a result of the influence of networking in many aspects of people's lives, the demands of network's peed, network's load and some other services provided by network become higher and higher.The use of optical network is a big step forward to network development. Optical network can greatly improve the transmission speed. SDH, ATM and other modes of transmission can also be used on optical network and that has improved the utilization of network resources. But traditional optical network's architecture is divided into two planes, transmission plane and management plane. It mainly relies on people to configure the network connection that is laborious, time-consuming and very prone to error. And for that matter, the traditional optical network is difficult to adapt to modern network requirements, and also difficult to adapt to market competition.ASON (Automatically Switched Optical Network) uses the control plane to complete the automatic exchange and connection control. ASON's architecture is divided into three planes: transmission plane, control plane and management plane. The core of ASON is the control plane. The transport plane is responsible for transmitting user data by connections. The intelligent control plane is responsible for resource management and connection management. The management plane is responsible for managing the control plane, it also has additional responsibilities such as fault management, traffic flow, safety management and so on. The introduction of the control plane has realized the real-time control of transmission plane, and made the connection, protection, restoration and the resource management intelligent. The network's realization of intelligent is a big step forward to Optical network.Network survivability refers to the network's ability of withstanding failures; even after catastrophic breakdowns it is able to maintain the quality of service in an acceptable range. Networks can recover from failures without human intervention, such network is called self-healing network. Survivability is important to the network which provides various services to users. The self-healing ability of network is an important aspect to judge whether network is good or not. If a network failure, it should have the ability to adopt appropriate methods to operate in the shortest time then making the business on the network work normal or be effected in an acceptable range. The protection switching function of Automatic Switched Optical Network is a means to improving the network survivability.Different from traditional optical network, the control plane can be involved in the protection switching function implementation. The survivability of ASON includes the protection mechanisms and restoration mechanisms. Protection mechanism is required to pre-establish one or more protection connections in order to protect one or more connections. If the protection resources have not be used, it will also not be used in re-routed. Then these middle nodes which are used to protect will also be configured in advance, and these middle nodes will not be changed when the protection connection is needed to be used later. Restoration mechanism refers to establishing new connections by re-routing in order to replace the faulty connections. New connections will occupy a shared capacity of the network redundancy.This article's background is the Z's key project "A110" ASON control plane system. The author refers to the research results in related fields at home and abroad, participates in an in-depth study of the control plane M: N protection group then completed the article. This article focuses on the research of protection switching sub-module and the improvement of the switching speed.The survivability is an important indicator to measure if a network is good or not. In order to improve the network survivability, we need to process the failure of network and to prevent failures affecting the quality of the business. We can not guarantee a problem free connection, but we can set protection mechanisms. The significance of ASON's protection switching sub-module is mainly to determine two things: 1. The self-healing of network that is the working connection can automatically switch to the protection connections when the working connection fails, thereby protecting the business operation. 2. The network optimization or maintenance that is the working connections can be switched to the protection connections manually, to optimize or maintain the original working connection. To achieve the above two points, we must first guarantee that the system can make the right switching judgments according to various aspects of conditions and to the protect connections correctly. This is the last process to ensure that the rate of switching is in the permitted range. These three points are the research content of this article.According to industry standards, if the control plane participates in the switching process, the time of protection switching needed to control is less than 200ms. By the research, author use the "head and tail node parallel processing" and "merger cross-process" methods to provide a fast and efficient method of protection switching, which make the switching time from 500ms down to 170ms, reaching the industry's advanced level.Automatic Switched Optical Network technology has gradually matured. Applications have also been expanded, although there are still many problems to be solved, but as the commercial level of the intelligent optical network is increasing, research efforts are also on the increase. I believe that in the near future these problems will be solved step by step, Automatic Switched Optical Network will give people's lives and work more and more convenience. |
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