In resent year, Internet has taken on an explosive improvement in the global Scope it has changed from the traditional services such as file transfer, E-mail, telnet to the WWW accompanied with abounding applications of Multi-media.

• 近年来,Internet在全球范围内呈爆炸性增长，其主要业务己由传统的文件传送、电子邮件和远程登录等转向多媒体应用丰富的WWW。 用户数的巨增对带宽要求的提高，导致Internet上的数据流量持续增加，网络拥挤程度加剧，数据传输延迟不断增大，阻碍了Internet的进一步发展。