New Features in the Windows 2000 TCP/IP Suite

The new Microsoft TCP/IP suite is designed to adjust itself for reliability and performance. The next four sections discuss the new features in the TCP/IP suite.

Automatic Private IP Addressing Configuration

Automatic Private IP Addressing (APIPA) configuration consists of automatically allocating a unique address in the range of 169.254.0.1 through 169.254.255.254, with a subnet mask of 255.255.0.0 when a DHCP server is not present. APIPA is used for single subnet networks such as SOHO networks that are too small to justify running a separate DHCP server.

For example, if you have a home office and need a way to distribute IP addresses to internal Windows 2000 servers and clients, all you need to do is to connect the systems together through a network medium, then each Windows 2000 computer self-assigns an address from the APIPA address range.

Large Window Support

Large receive window support increases the amount of data that can be buffered on a connection at one time, reducing network traffic and speeding up data transfer.

Note

Large window support is not enabled by default. The window size defaults to about 16 kilobytes (KB), which is double the window size of Windows NT 4.0.

Selective Acknowledgment

Selective acknowledgments allow the receiver to inform the sender to retransmit only the data it has not received as opposed to entire blocks of data. This enables more efficient use of network bandwidth.

Improved Estimation of Round Trip Time

TCP uses round trip time (RTT) to estimate the amount of time that is needed for roundtrip communication between the sender and receiver. Windows 2000 TCP makes better estimates of RTT for setting transmission timers, which improves overall TCP performance. This improvement in TCP primarily helps in WANs that span very long distances, or over slow links such as satellite communication.