UDP实现可靠文件传输 既能实现UDP传输的速率，又能保证可靠，对丢包，乱序等进行处理后组合-UDP reliable file transfer both UDP transmission rate, but also ensures reliable, packet loss, out-of-order processing combination

pon减少时延，并提高网络吞吐量以及减少丢包率。-pon reduce latency and improve network throughput and reduce packet loss rate.