By standardizing and enhancing TCP/IP, Microsoft has made Windows 2000 the ultimate Internet server, capable of world-class Web serving performance, advanced routing capabilities, and support for secure Virtual Private Networks (VPN), to name a few obvious benefits.

And TCP/IP is thoroughly integrated into Windows 2000. For example, the new directory service in Windows 2000, known as Active Directory, builds off of TCP/IP and related Internet technologies such as DNS. By embracing these established standards, Microsoft ensures that Windows 2000 will be a good Internet citizen.

Introduction to TCP/IP
TCP/IP (Transmission Control Protocol/Internet Protocol) is a suite of protocols that define how Network Interface Cards (NICs) and other devices (commonly referred to as hosts though this word is also erroneously used to describe individual computers) communicate over a network. TCP/IP is a routable network, meaning that individual hosts can automatically forward TCP/IP information--called packets--intelligently to the proper locations. And, as you probably know, TCP/IP is the network protocol on which the Internet is based: All Internet locations are described in relation to their TCP/IP network address.

Because TCP/IP is a suite of protocols and not just a single protocol, it is often described as a tiered set of four layers. On the lowest level is the Network Interface, which describes low-end interfaces to physical LAN and WAN technologies, such as Ethernet (cabling) and frame relay.

Just above this level is the Internet layer, which is the domain of the Internet Protocol (IP). IP describes how packets are transported and routed across a network.

Above IP is the Transport layer, which includes TCP and UDP (User Datagram Protocol). This layer is responsible for handling host to host communications, with UDP handling small packets of data while TCP is responsible for the more reliable connections required by large amounts of data.

At the uppermost level is the Application layer, where Windows applications access the network. Common Internet applications such as FTP, Telnet, and DNS interact with TCP/IP at the Application level.

Given these levels, the name TCP/IP might make a big more sense: Literally, it means "Transmission Control Protocol over Internet Protocol."

Windows 2000 Improvements to TCP/IP
The TCP/IP standard has existed relatively unchanged for some time. But Microsoft has improved its implementation of TCP/IP in Windows 2000 to include optional (yet still standardized) features that aren't often used in other operating systems, including previous versions of Windows NT.

At the top of this list is packet filtering, where IP packets that are routed through a Windows 2000 Server can be filtered to allow or disallow certain types of network traffic. So, for example, you can protect internal networks from specific kinds of traffic, such as Internet POP Mail or Web traffic, if desired.

Windows 2000 also enables the use of Virtual Private Networks (VPN) where secure data can travel safely over an unsecured network such as the global Internet. This way, mobile users can connect to the internal network from a dial-up connection anywhere in the world and be sure that their communication with the network is secure.

Another exciting addition to TCP/IP in Windows 2000 is Network Address Translation (NAT), a routing technology that allows a Windows 2000 Server to share a single Internet connection--be it dial-up or network interface card-based--with all of the machines on a private network. Previous to the inclusion of this capabilities, administrators needed to purchase separate connection sharing applications such as SyGate or Proxy solutions such as Microsoft Proxy Server or WinGate.

TCP/IP is bound to a NIC, not a computer
Windows 2000, like other advanced Network Operating Systems (NOS), supports multiple NICs in a single computer. This setup, which is known as multi-homing, allows you to connect a single computer to multiple networks, one per card. So, for example, you might establish a Server that acts as a gateway to your local network. One NIC would connect the Server to your local network, while the other could be used to communicate with an external network, such as the Internet. You'll often see a Web server used in this way, where the machine serving Web pages needs to be accessed from the Internet and the local network. This setup is also required to implement NAT, which is sometimes referred to as Internet Connection Sharing.

Installing and Configuring TCP/IP
Typically, TCP/IP is installed and configured during Windows 2000 Server setup, but you can install and/or configure it at any time if you install a new network interface card or decide that you need to make configuration changes later.

To install TCP/IP after Windows 2000 Server has already been setup, simply launch the Network and Dial-up Connections applet in the Control Panel. This supplies an Explorer-based front-end to the network connections that are configured for the server.

By default, TCP/IP network connections are named "Local Area Connection," "Local Area Connection 2," and so on. You can change these names to something more descriptive by simply click twice slowly on the name of the connection icon in Network and Dial-up Connections. For example, on a multi-homed system that acts as a gateway to the Internet, you might name the external connection as ISP connection and the internal connection as Internal connection or similar.

You can edit the properties of any network connection by right-clicking its icon and choosing Properties. In this dialog, you can access the settings for any service, protocol, or client software that's been configured for that connection. If TCP/IP has already been installed, one of the listed installed components will read as Internet Protocol (TCP/IP). If TCP/IP isn't installed, you can install it by clicking the Install button and choosing Protocol then Internet Protocol (TCP/IP).