Research Of Multimedia Multicast In Switch Ethernet

The future of the "last-mile" belongs to Ethernet because of its low-cost, high-speed and powerful functions. The multicast technology makes it very easy to provide the broadcast TV service in computer network, and improves the development of collaboration applications and shared services. However, traditional Ethernet lacks the support for multicast services and multimedia real-time services. It leads to inefficient usage of network resource and provide no guarantee for the quality of services. Under such background, this dissertation makes the research in the mechanisms of multimedia multicast service in Switch Ethernet, and provides traditional broadcast TV and multimedia multicast applications with a total solution for the efficient transfer and guarantee of QoS. The following are the main contributions of this dissertation.1. The first is an IGMP-Snooping-based multicast protocol of link layer in Switch Ethernet. It maps a group of hosts in an IP multicast group to a group of ports in a VLAN, a communication group in link layer. The presented protocol manages the ports' dynamic join and exit to groups by the IGMP modules of hosts, router and switch, and makes the distribution of multicast data by VLAN of switch. Using this protocol, Switch Ethernet can provide the support for multicast service without any change in terminals and routers. This method not only saves the network bandwidth but also integrates the link layer multicast with IP multicast.2. The second is an adaptive traffic shaping algorithm based on DLB. This algorithm is used to smooth the traffic with a large fluctuation of output rate. It can estimate and compute the average input rate of the traffic online by monitoring the change of the length of the data buffer. It updates the settings of the traffic shaper depending on the rate changes of the source traffic so as to provide smoothed stream under limited resources. The algorithm presented in this thesis doesn't need to pre-analysis of the source traffic, so as to make it possible for online traffic shaping.3. The third is a reliable multicast protocol for real-time continuous- media streams on Switch Ethernet, which makes use of the Ethernet's characteristic of low-delay, flat topology and high-reliability. The acknowledgement andretransmission technology is used for the recovery of the lost packets; NAK suppression is used to address the NAK implosion problem; and limited retransmission by real-time playback avoids producing unused retransmission data. This protocol improves the effectiveness and reliability of the continuous media multicast streams under real-time playback. The reliability depends on the data pre-buffering time in receivers and the size of retransmitted buffer in senders.Overall, by combining the IGMP Snooping protocol, traffic shaping algorithm, reliable multicast and current IP multicast mechanism, this dissertation presents a framework for multimedia multicast applications in Switch Ethernet, to provide a service platform with guarantee of QoS for DTV access, Multicast Streaming and WebCasting, to provide an IP-based architecture for Broadband Integrated Service Community Network and finally to provide an implementation of a typical DTV access system based on this architecture.