组播的基本概念 组播服务的支 共享学习:如果发现了丢包现象,接收者启动 个随机的定时器。如果在定时内收到其它接 收者的丢包报告,就停止定时器并且不发送丢 Heterogeneous包报告,否则就发无包报告发送者通过 Sending to recei决定是否调整数据发送速率 bandwidth capacity ncy characteristics, and network cop on requires feed back to monitor receir performance Shared Learning, Local recovery Reliable data delivery E d by all re( 本地恢复:一些接收者被定义为本地转发点,它 可以在收到本地的丢包报告后重发数据包,或者将 Si接收到的数据重新编码为速率较低的数据,再向低 速信道转发。 东南大学8东南大学 8 组播服务的支撑 组播服务的支撑 • Heterogeneous Receiver Support – Sending to receivers with a wide variety of bandwidth capacities, latency characteristics, and network congestion requires feedback to monitor receiver performance. – Shared Learning，Local Recovery • Reliable Data Delivery – Ensuring that all data sent is received by all receivers – Similar mechanisms as above 组播的基本概念 共享学习：如果发现了丢包现象，接收者启动 一个随机的定时器。如果在定时内收到其它接 收者的丢包报告，就停止定时器并且不发送丢 包报告，否则就发送丢包报告。发送者通过 RTP/RTCP协议了解接收者总体的丢包率，以 决定是否调整数据发送速率。 本地恢复：一些接收者被定义为本地转发点，它们 可以在收到本地的丢包报告后重发数据包，或者将 接收到的数据重新编码为速率较低的数据，再向低 速信道转发