(第3空)The Internet is based on a connectionless end-to-end packet service, which traditionally provided best-effort means of data ( )using the Transmission Control Protocol/Internet Protocol Suite. Although the ( )design gives the Internet its flexibility and robustness, its packet dynamics also make it prone to congestion problems,especially at ( )that connect networks of widely different bandwidths.The initial QoS function set was for internet hosts.One major problem with expensive wide-area( )links is the excessive overhead due to small Transmission Control Protocol packets created by applications such as telnet and rlogin. The Nagle ( )，which solves this issue,is now supported by all IP host implementations.