卫星网络大时延、高误码率及链路不对称等特点,使得TCP/IP协议无法提供令人满意的服务。针对卫星网络的特点,设计了SaclTCP协议,采用跨层设计思想减少层次网络的冗余性,实时获取网络状态信息。协议根据链路层反馈的有效带宽信息准确地设定拥塞窗口门限阈值;在网络层对路由器缓冲队列进行管理,计算网络发生拥塞的概率并发送显示拥塞通知反馈给发送方传输层;还可区分丢包原因,避免由于传输错误造成的发送窗口减小。实验结果表明与传统协议相比,极大提高了传输性能。Satellite network has some special characteristics, such as the big propagation delay, high bit-error rate and asymmetric channels, and these characteristics make TCP/IP protocols incapable of providing satisfying service for satellite network. The idea of cross-layer design can reduce the redundancy of multi-layer, and capture network status information at any moment. The protocol can set a window congestion gate-limit threshold more effectively by getting the available bandwidth information from the link layer. And in the link layer a router buffer queue managing mechanism is set to compute the network congestion probability and then feedback it to the sender. It can also differentiate the packet losses between congestion and link error to avoid reducing the send window unnecessarily. The protocol will use this information to regulate the size of window dynamically. The experiment shows the protocol greatly improved the transport performance of satellite networks
