【作者】 傅韬；

【导师】 王芙蓉；

【作者基本信息】 华中科技大学 ， 通信与信息系统， 2006， 硕士

【摘要】 软交换的基本含义就是将呼叫控制功能从媒体网关中分离出来，通过软件实现基本呼叫控制功能。与传统的程控交换机相比，软交换基于分组交换技术，能够实现低成本的语音传送、传真等传统电信业务，并对新兴数据业务提供有力支持。但是由于它的发展时间尚短，从而软交换设备的可靠性不能与传统交换机相比，如何提高软交换设备的可靠性，是软交换技术广泛应用的关键。压力测试是检验设备可靠性的一个重要环节，在压力测试中所用的主要工具是大话务量呼叫模拟器。它是一种能够模拟许多电话用户，同时或轮流向软交换系统发起大量完整呼叫的工具。以软交换技术为核心的网络是基于统一协议、分组网络、业务驱动的开放网络，能够提供多种业务的连接控制、路由、网络资源管理、计费、认证等功能。软交换设备与各种媒体网关、终端、应用服务器、其他软交换设备间采用标准协议相互通信。整个软交换网络体系结构包括接入层、传送层、业务控制层、业务管理层和网络管理层包含五个层次，各层的功能及相关设备均不相同。在实际应用的H.323网络体系架构中包括了网关、网守、后台服务器三个层次。当设计的大话务量呼叫模拟器运行于WINDOWS平台下，并且呼叫连接采用TCP协议时，任务体系结构的选择是一个非常重要的问题，采用线程池技术能够使模拟器的性能最优化，并降低网络的拥塞。同时，根据软交换系统的被测功能，可以将呼叫流程进行简化，提高模拟器的性能并降低模拟器结构的复杂度。考虑到模拟器的可移植性，设计一个系统接口模块是必要的，同时，采用有限状态机的方法可以简化程序的结构，建立统计信息表有利于在测试中发现问题。大话务量呼叫模拟器的设计基于面向对象的思想，将每个模拟的终端看成一个对象，这些对象各自独立与待测交换系统完成信令交互。整个模拟器的结构从上而下可以分成用户控制层、流程控制层和协议栈层三个层次，用户控制层接受用户配置的话务参数，并通过定时器驱动流程控制层发起呼叫；流程控制层规定呼叫流程，同时对收发的信令信息进行统计；而在用于编解码的协议栈时，在条件允许的情况下，模拟器一般采用与待测系统不同的协议栈。实现了H.323网守的大话务量呼叫模拟器后，并利用此模拟器对H.323网守进行了压力测试，获得H.323网守的初步性能指标，H.323网守在实际大规模的应用中也获得了令人满意的效果。更多还原

【Abstract】 Softswitch which means separates the call control function from the media gatewayachieves to control the call by designing software. Compare to the traditional switcher,Softswitch can cut down the cost, support many new operation and be convenient toapplicate . But because of shortage of the time after its’generation, and also the Internet is a“best effort delivery”Network, the reliability of the Softswitch equipments is not as good asthe traditional switcher. So how to improve the reliability of the equipments is the key topopularize Softswitch. Stress test is a important process when checking up the reliability ofthe equipments. The bulk call simulator is the main implement when executing the stress test.It can simulate many phones, and sends calling requirements to the Softswitch equipmentsat the same time of alternate.The softswitch network is based on standard protocols, transferred by grouping anddrived by the operation. The network can support routing, accounting, network managementand authentication. The softswtich equipments exchange message with the media gateways,terminals and servers. This architecture of the softswitch network includes 5 layers: theaccess layer, the transaction layer, the operation control layer, the operation managementlayer and the network management layer. In H.323 network architecture, there are 3 layers:gateway layer, gatekeeper layer and backend server layer.When the bulk call simulator running on WINOWS and uses TCP protocol to establishconnect, how to choose the task architecture is a very important problem. The technology ofthread pool can enhance the capability of the simulator and reduce the congestion of thenetwork. To predigest the call flow is also profit to enhance the capability of the simulator.Also how to import the abnormal call flows, pay attention to the transplant of the simulatorand establish the statistics table is very import.Based on the Object Oriented thesis, each terminal could be seen as a object. Theyexchange the messages with the softswitch equipments. The architecture of the simulator isdivided into 3 layers: the user layer, the flow control layer and the protocol stack layer. Theuser layer is used to input and show the configuration. The flow control layer is used tocontrol the register and call flow. The protocol stack layer is used to coding and decodingthe protocol messages.At last, the article tests the gatekeeper with the simulator and the test results issatisfactory .更多还原