共查询到18条相似文献,搜索用时 171 毫秒
1.
2.
3.
4.
首先简要介绍了软交换的定义和功能,接着阐明了软交换设备的组网结构、实现软交换设备互通的两种协议,即:SIP-T和BICC,并对其进行了分析和比较,然后给出了用SIP-T实现软交换设备间互通的典型流程以及ISUP和SIP在消息级和参数级的映射和转化方法。 相似文献
5.
6.
7.
SIP可视电话系统的信令流分析 总被引:1,自引:0,他引:1
文章从会话初始协议SIP(SessionInitiationProtocol)的基本概念出发,首先描述了SIP可视电话系统中的协议栈结构、功能实体部署图和在IPv6下的运行环境,接着重点分析了通信域内速拨和域间直拨两种呼叫方式中的SIP信令流程,最后总结了该系统中体现出的SIP协议优势。 相似文献
8.
9.
SIP(Session Initiatioan Protocol)协议是由IETF工作组于1997年7月提出的,是应用层的控制协议,能建立、调整和终止多媒体的呼叫和会话。SIP协议是基于文本方式的,即以明文方式传输。SIP消息包括请求消息、应答消息。SIP协议侧重于将IP电话作为因特网上的一个应用,并且也采用RTP作为媒体传输的协议。本文在SIP通信过程中,采用面向连接的TCP来传输SIP的交互信令,采用面向无连接的UDP协议进行实时音频流传输。本设计是在Linux操作系统下,用套接字(socket)来实现的。设计实现了SIP协议的整个通信过程。最后,提出了进一步开发的设想。 相似文献
10.
11.
3GPP在R5版本中首次提出了IP多媒体子系统(IMS)的概念,SIP协议被选择为呼叫会话控制协议。由于SIP是基于文本的协议,在会话过程中需要重传大量的数据,导致在会话建立过程中时延的增加。文中在分析现有的SIP信令压缩算法的基础上,提出了一种带有预处理的LZSS与算术编码相结合的改进算法。首先对消息进行预编码,然后进行LZSS压缩,压缩完后与算术编码相结合,这种改进后的算法减少了信令传输延迟。文中运用典型的SIP会话环境进行仿真实验,其结果验证了改进算法能够有效地提高性能,缩短消息长度和减小传输时延。 相似文献
12.
独立媒体服务(IMS)是第三代合作伙伴计划(3GPP)在版本5中提出的支持IP多媒体业务的子系统,而基于文本的SIP消息过大成为其在IMS无线环境应用下的瓶颈,因此采用会话初始化协议(SIP)来建立和维护多媒体会话。在SigComp框架下,将改进后的LZSS算法与算术编码相结合对SIP信令进行压缩。实验表明新的算法有较高的压缩率,对改善IMS的SIP会话建立延时有一定的参考价值。 相似文献
13.
Michael Gläser Sebastian Müller Axel Rennoch Peter Schmitting 《International Journal on Software Tools for Technology Transfer (STTT)》2008,10(4):353-358
ETSI technical committee TISPAN currently funds the development of TTCN-3 network integration test suites using TTCN-3. Specialist
task forces (STF) have already been initiated to implement and validate abstract test suites focusing on, e.g., SIP/ISUP and
SIP/ISDN interworking units. In this paper, we report on our implementation approach and experiences made in the STF on testing
interworking between SIP and ISDN/ISUP. Special attention has been given to the reuse of know-how and of existing TTCN-3 code
available due to the existing SIP conformance test suite and the TTCN-3 test framework developed by ETSI for IPv6. Validation
has been done using the test laboratory of a telecom network provider. 相似文献
14.
15.
Within the standard IMS framework, the value-added service is executed in the Application Server (AS) when the expected event happens. In order to be aware of the event, the AS should be inserted into the SIP signaling path at the beginning of the call to monitor the call progress. As a result, all SIP messages related to the session have to be relayed to the AS to determine whether the service is to be executed or not. However, some services are rarely executed; that is, the procedure of relaying messages to the AS seems unnecessary for most cases of these services. This paper proposes a distributed service invocation function (DSIF) to eliminate the unnecessary relay. The DSIF works as an overlay on the top of the current IMS infrastructure that enables operators to deploy it without any change in the existing IMS core; thus, it can be applied transparently to SIP dialogs between the S-CSCF and the AS. The DSIF consists of two functional entities: the Core network-SIF (C-SIF) and the Application side-SIF (A-SIF), and one database node: DB-DSIF. The C-SIF is responsible for allowing the messages to be relayed to the AS only when the service really needs to be executed. The operation of C-SIF is based on two new defined types of filter criteria: trigger Filter Criteria (tFC) and execution Filter Criteria (eFC), which are stored in the DB-DSIF. The A-SIF is in charge of interacting with the AS for service invocation. Our study indicates that the DSIF achieves a shorter service invocation time with a lower message transmission cost. We also demonstrate its feasibility by implementing a prototype on Open IMS Core platform. 相似文献
16.
17.
针对基于会话初始协议(SIP)的IP多媒体子系统(IMS)网络安全机制,分析了SIP协议存在的安全隐患,将身份密钥协商协议IBAKA和头域敏感信息完整性保护等机制有效结合,提出了基于身份密码的轻量级SIP安全方案。分析了该方案的安全性,并从安全性和抗攻击性方面与几种典型方案进行比较。比较结果表明,该方案克服了SIP协议的安全隐患,提高了协议的安全性。 相似文献
18.
对会话初始化协议(SIP)分布式洪泛攻击的原理进行研究,结合SIP协议自身的特点提出一种基于安全级别设定的攻击减弱方法.该方法将SIP消息按照历史记录、协议自身进行安全级别分类,利用流量监控对SIP流量监控.当发生分布式洪泛攻击时,通过设定合适的安全级别减弱攻击造成的影响.仿真实验结果表明基于安全级别的方法能够识别和防御SIP分布式洪泛攻击,有效地减弱SIP代理服务器/IMS服务器被攻击的可能性. 相似文献