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随着IP网络的普及,私有网络(简称私网)的数量和规模也越来越大。由于IPv4地址紧张和网络安全等问题,私网上普遍放置了NAT、防火墙设备,因此,H.323协议的NAT、防火墙穿越问题成为开展视讯业务首需解决的问题之一。其关键在于目前大部分NAT设备都不支持H.323协议的穿越,即使部分NAT设备支持H.323穿越,但又不能做到多个私网终端共用一个公网IP地址,从而失去了使用NAT的意义。如果NAT设备在进行NAT转换的同时能支持H.323协议,就可以在节约公网IP地址的同时解决NAT、防火墙穿越问题。现阶段业界普遍采用以下几种方式来解决私网穿… 相似文献
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目前,NGN网络正逐步从试验走向商用,在应用过程中出现了很多实际问题,特别是NGN用户的接入问题。NGN是基于分组网承载的网络,接入用户是通过IP地址来寻址的,由于当前IP地址紧缺以及网络缺乏安全等原因,大量的企业网和驻地网基本都采用私自IP地址通过山口的NAT/FW接入公网。而目前NGN网络中,如H323、SIP、MGCP、H248等在IP上承载语音和视频的协议的控制通道或媒体通道在私网用户接入应用中难以穿越传统的NAT/FW设备与公网进行互通,或说目前的NAT/FW大多支持HTTP的数据应用协议穿透,而无法 相似文献
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H.323视讯网关键问题探讨 总被引:2,自引:0,他引:2
视讯业务是当前宽带业务中发展的重点,而IP视讯业务网又多采用H.323技术和设备。本文简述了H.323协议、H.323视讯业务网的组成结构及构建H.323视讯业务网的一些问题。 相似文献
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H.323视讯会议技术的发展使得视讯会议需求变为现实,通过视讯会议系统可以依托原有的IP网络召开覆盖全网的多点视讯会议,实现双向的实时交互;并能够借助该系统实现远程电视教学、远程图文共享及网上会见等功能。与传统的基于电路交换的H.320技术不同,H.323是一种基于IP网络包交换的视频会议技术标准,它为音频、视频及数据在IP网络—— 相似文献
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中国联通“宝视通”宽带视讯网是基于中国联通数据综合业务承载平台,采用基于IP技术的H.323技术体制,向用户提供视讯及其增值眼务的公用视讯交换平台。经过两期工程的建设,全网多点交换容量已达到3500多个384kbit/s端121,可以支持3500个终端同时召开多组视讯会议。业务范围已经覆盖全国320多个地市、香港特别行政区、台湾地区以及美国、澳大 相似文献
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本文首先介绍了目前企业网使用防火墙及NAT设备的情况,以及防火墙/NAT设备对基于H.323/SIP协议的视讯通信造成的影响。通过对几种透传防火墙的方式的比较,着重介绍了全代理模式的信令处理流程及优点,以及该系统在联通“宝视通”业务中的成功应用。 相似文献
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简要介绍了IP网络基于H.323的视讯会议系统的发展状况、相应标准的研究进展和主要设备的测试情况,并根据国内视讯业务发展和实际测试中的情况,对视讯会议设备本身需要面对的一些问题进行了探讨。 相似文献
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在IPv4公有地址即将耗尽的背景下,互联网从IPv4向IPv6演进已刻不容缓。本文对基于NAT444的IPv6过渡方案进行了研究和探讨。对NAT444的技术原理进行介绍,结合目前电信运营商IP城域网的现状提出了基于NAT444技术的部署方案,包括部署方式、冗余保护、端口分配、地址分配、接入流程及其他相关支撑系统配合改造等。 相似文献
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媒体分发服务器是网络视频监控平台中负责流媒体分发的重要模块.网络地址转换器 (Network Address Translator,NAT)能很好地解决IPv4地址资源匮乏的问题,但同时也给各个私网用户之间或私网与公网用户之间的通信带来了障碍.文章主要介绍这种NAT障碍的形成,并给出了会话初始协议(SIP)下媒体分发服务器实现NAT穿越的一种方案. 相似文献
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网络安全协议(IPSec)和网络地址转换(NAT)是当前的热点技术,在因特网上都得到广泛应用,但两者在协议设计时存在的兼容性问题成为阻碍这两种技术得到进一步应用的关键问题。本文分别介绍了NAT和IPSec两种协议的基本原理,并对两者存在的不兼容性进行了详细的分析,最后给出了利用UDP封装ESP数据包的解决方案。 相似文献
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In this paper, technologies for distribution of a variety of three-dimensional (3-D) video and 3-D TV services over IP networks are described. The approaches for encoding stereoscopic and MW have been standardized in the form of MPEG "video-plus-depth" and the JVT MVC standards. It has been shown that both approaches can encode stereoscopic video at about 1.2 times the bit rate of monoscopic video (when using unequal inter-view bit allocation in the case of MVC). Also this kind of interactive system increases the bandwidth requirement significantly. A multitude of strategies have been considered for streaming such encoded MW using RTP/UDP/IP or RTP/DCCP/IP. Video streaming architectures can be classified as 1) server unicasting to one or more clients, 2) server multicasting to several clients, 3) P2P unicast distribution, where each peer forwards packets to another peer, and 4) P2P multicasting, where each peer forwards packets to several other peers. 相似文献
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Providing efficient mobility management in the current Internet is increasingly important due to the quick growth of wireless mobile users. The emerging Proxy Mobile IPv4 (PMIPv4) technique brings a possible solution for that purpose. Since NAT function is widely adopted in IPv4 environment nowadays because of lacking IPv4 addresses, the PMIPv4 interoperating with NAT must be considered. Unfortunately, owing to the possible conflict of private IP address, we encounter a problem in broadcasted point-to-multipoint wireless networks such as IEEE 802.11 networks. To address this issue, we proposed a novel Network Address Translation on Demand (NAToD) scheme, which can well interoperate with the PMIPv4 solution. With our scheme, single public IPv4 addresses can be shared by multiple mobile nodes in both home and foreign networks, low-latency handoff can be achieved, deployment cost can be reduced, and software upgrade can be avoided for mobile nodes in wireless LANs. Our work allows mobile users in WLAN to access Internet based on the advantages of both PMIPv4 and NAT. 相似文献
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SIP-based enterprise converged networks for voice/video-over-IP: implementation and evaluation of components 总被引:1,自引:0,他引:1
Chatterjee S. Tulu B. Abhichandani T. Haiqing Li 《Selected Areas in Communications, IEEE Journal on》2005,23(10):1921-1933
The next generation of enterprise networks is undergoing major changes as a plethora of new architectures, applications, and services begin to roll out within businesses. In general, the world of voice/telephony, video, and data are "converging" into a global communications network. The purpose of this paper is twofold. First, the design, analysis, and performance of a session initiation protocol (SIP)-based videoconferencing desktop client, which has been developed and deployed over Internet2, is presented. Second, a guideline for managing SIP-based services to be deployed within enterprises, which addresses several challenges in each layer, such as network address translator (NAT)/FW issues, directory service integration issues, and interoperability issues, is proposed. Several detailed experimental results related to interoperability and conformance that were carried out are presented. Findings of extensive SIP/NAT traversal analysis through network traffic measurements are reported. The lessons learned from both the design of a new SIP-based voice/video client, as well as management challenges with enterprise deployment are highlighted. 相似文献
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Ip网络中网络地址转换器(NAT)的存在给基于会话初始协议(SIP)的IP电话(SIP电话)的大规模应用造成了较大困难,为解决SIP电话的NAT穿越问题,分析了完全圆锥型、地址受限圆锥型、端口受限圆锥型、对称型等NAT的特点,比较了应用层网关、基于用户数据报协议(UDP)的NAT简单穿越、采用中继的NAT穿越、会话边界控制器等各种NAT穿越技术的优缺点.以一典型的SIP电话系统为例,针对其应用需求,提出了一种NAT穿越方案,并给出了通信流程.该NAT穿越方案特别适合于对网络结构无限制,网络设备不改造的应用环境. 相似文献
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针对IP视频通信来实现端到端的业务控制,始终是研究的热点问题。本从视频传输机制和业务接入控制机制两个方面对IP视频通信控制机制进行了分析,最后,给出了在城域IP网内实现IP视频通信端到端的控制策略。 相似文献