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1引言随着网络技术的发展,语音、视频和数据业务逐渐融合在同一网络链路上,而网络能否为不同业务提供服务质量(QoS)保证成为关注热点。QoS需要根据协商的传输速率(保证最小包丢失)制定,同时,一个优良的网络必须达到高复用性、高吞吐率和QOS保证。ATM网络是一种实现端到端连接的网络体系,在虚电路上用固定长度的信元(53Byte)传送数据,为几种不同类型的服务提供同一种结构,并且为这些服务指定QOS保证。它提供包括恒定位率(CBR)和实时可变率(RT-VBR)、非实时可变位率(NRT-VBR)、可用位率(ABR)、可保证帧率(GFR)和非确定位率(UBR)等多种服务,其中ABR业务是通过反馈控制来调节信源速率,在保证QOS的基础上最大限度地利
1 Introduction With the development of network technology, voice, video and data services are gradually converged on the same network link. Whether the network can provide Quality of Service (QoS) guarantee for different services becomes a hot issue. QoS needs to be negotiated based on the negotiated transmission rate (minimum packet loss guaranteed), while a good network must achieve high reusability, high throughput, and QOS assurance. An ATM network is a network system that enables end-to-end connectivity. It delivers data over fixed-length cells (53Byte) over virtual circuits, provides the same fabric for several different types of services, and assigns QOS assurances to these services. It offers features including Constant Bit Rate (CBR) and Real Time Variable Rate (RT-VBR), Non-Real Time Variable Bit Rate (NRT-VBR), Available Bit Rate (ABR), Guaranteed Frame Rate (GFR) Rate (UBR) and other services, including ABR business through feedback control to adjust the source rate, to ensure maximum QOS on the basis of