The Internet is based on 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 （请作答此空）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.