摘要
随着因特网数据业务的快速发展,在IP业务作为主导的今天,传.统的传送设备有以下两个缺陷：随着分组业务的增加,传统的SDH设备不能很好的处理大规模的业务,容易产生网络拥塞；由于存在无连接和尽力传输的特性,传统以太网设备无法满足传送TDM业务和高可靠性、实时数据业务的要求。针对上述缺陷,MEF[1]提出了运营级以太网的概念。运营级以太网通过增强以太网的电信级业务能力来’实现分组传送和高质量的多业务承载,克服了以太网在可靠性,服务质量QoS、可扩展性、同步和安全性等方面的缺陷。网络可靠性是运营级以太网的一个重要特征,网络上某条链路出现故障,运营级以太网要求具有50ms以内的保护倒换能力。保护倒换的技术主要包括环网保护和线性保护,对于环网上的两台设备来说,环网上有两条路径连接这两台设备,能实现最为经济的冗余保护,所以环网技术是当前研究的热点,各大设备商和标准化组织都在推动环网保护技术的发展和标准的制定。
环网保护技术在运营级以太网中的应用是本文的研究重点。基于I-TUT G8032标准提出快速环网保护协议方案,以工业以太网交换机为硬件平台,以VOS虚拟操作系统为软件平台,设计并实现快速环网保护协议软件模块。下面介绍本文所做的主要工作：
一、介绍电信级以太网的产生及关键技术点,增强型的以太网和分组传送网络都具备电信级以太网的特点。从环网保护目的、保护对象、实现方案、标签分配机制、组网情况、资源占有和配置维护复杂性对两种情形下的环网保护技术进行比较。
二、结合环网保护技术的比较结果,提出快速环网保护协议设计方案。快速环网保护协议设计方案的核心是基于I-TUT G.8032标准的,主要关注链路故障检测机制的实现、复杂网络拓扑下的故障通告机制、单环单点故障的保护倒换、单环多点故障的保护倒换、多环单点故障的保护倒换以及互联节点之间出现多点故障时的保护倒换。
三、根据快速环网保护协议设计方案,提出快速环网保护协议嵌入式软件设计方案。软件实现基于工业以太网交换机硬件平台和以VxWorks操作系统为内核的VOS软件平台。快速环网保护协议作为一个独立的软件模块运行在工业以太网交换机上,包括协议内核、与其他模块的接口。
四、快速环网保护协议嵌入式软件实现后,搭建单环测试网络和多环测试网络,对软件进行功能性和保护倒换性能测试。测试结果满足设计要求,快速环网保护协议能够正常运行,环网出现故障时保护倒换时间在50ms以内。
With the rapid development of the Internet data service, the IP data service has become the leading service today. The traditional transfer network equipment has the following two defects:With the data service increasing largely, the network capacity has to expand, the traditional based on SDH technology transfer network equipment will cause not enough data throughput and network congestion problem; Pure ethernet switching equipment cannot be effectively transfer TDM service for its connectionless characteristics, and can't solve the reliability, scalability and management problems very well. Faced with the above problems, Carrier Ethernet arises at the historic moment. Carrier Ethernet make the packet transmission and high quality service load become true by enhancing Ethernet carrier class service ability, and overcome the defects of Ethernet about the QoS, scalability, reliability, synchronous and safety. Network reliability is an important feature of Carrier Ethernet, when a fault is detected on a ring link, Carrier Ethernet's requirement for the protection switch time is less than50ms. Ethernet protection switching technology including linear protection and ring network protection, because the ring network has a unique advantage, it can realize the most economic redundancy protection, this technology is a hotspot of current researches. Many communication device companies and standardization organizations are promoting the development of ring network protection technology and the standards.
This paper is focused on the ring network protection technology of Carrier Ethernet. Fast ring network protection protocols is proposed based on the I-TUT G-8032standard, with the industrial Ethernet switching as hardware platform and with VOS operating system as software platform. Meanwhile the fast ring network protection protocol software module is designed and realized according to the above solution. The research and development work of this paper mainly includes the following several parts:
First, introduce the generation of Carrier Ethernet and the key technical point of it. Enhanced Ethernet and packet transport network both have the characteristics of Carrier Ethernet. From the ring network protection purpose, protection object, implementation scheme, the label distribution mechanism, networking, resources possession and configuration maintenance complexity, we make a comparison on the protection technology used in enhanced Ethernet and packet transport network.
Second, combined with the comparison results of Ethernet ring network protection technology, and puts forward the rapid ring network protection protocol design proposal. The core of fast ring protection network protocol design scheme is based on the I-TUT G.8032standard, which is focused on link failure detection mechanism, the fault notification mechanism of complicated network topology, protection switching of single ring single link failure, protection switching of single ring s multipoint link fault, protection switching of multipoint link fault between interconnected nodes.
Third, according to the fast ring network protection protocol design, this article puts forward the fast ring network protection embedded software design. The realization of software based on industrial Ethernet switch hardware platform and the VOS software platform whose kernel is VxWorks operating. As an independent software module, fast ring network protection protocol is working on the industrial Ethernet switch, including the realization of the kernel of fast ring network protection protocol, and other module application programming interface.
Forth, after realizing the fast ring network protection embedded software, build single ring and multi-ring test network, the test of software includes functionality performance test. Functional test aims at whether the protocol state machine can run normally, while performance test focuses on the ring protection switching time.
引文
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