就象功能强大的电话网络一样,Internet 正发展成连接全球几千万计算机的全球性通信网络,Internet 上还运行一些功能强大的应用。早期 Internet 主要被研究性团体用于 E-mail(电子邮件)和 FTP(文件传输),现在 Internet 已成为处理日常业务的全球性商业数据网络。因此它要求某种级别的服务质量(QoS Like a powerful telephony network, the Internet is evolving into a global communications network connecting tens of millions of computers around the world, with powerful applications running on the Internet. The early days of the Internet were largely used by research groups for e-mail and FTP (file transfer), and the Internet has now become a global business data network for everyday business. So it requires some level of quality of service (QoS)