Local and Remote Network Connections

With the Windows 2000 Internet Connection Sharing (ICS) feature of Network and Dial-up Connections, you can use Windows 2000 to connect your branch office network to the Internet. For example, you might have a home network, with only one of the home network computers connected to the Internet by using a dial-up connection. By enabling Internet Connection Sharing on the computer that uses the dial-up connection, you are providing Internet access to all of the computers on your home network, with only one computer physically connected to the Internet. ICS provides network address translation, IP address allocation, and name resolution services for all computers on your small office or branch office network that are configured for automatic addressing. For a detailed scenario that discusses setting up ICS in a branch office network, see Internet Connection Sharing Scenario: Connecting Your Branch Offices Intranet to the Internet later in this chapter.

After ICS is enabled and users verify their networking and Internet options, branch office network users can use applications, such as Internet Explorer and Outlook Express, as if they were already connected to the ISP. If the ICS computer is not already connected to the ISP, it dials the ISP and creates the connection so that the user can reach the specified Web address or resource.

The computer enabled with ICS needs two connections: One connection is for a network adapter, and connects to the computers on the home network. The other connection connects the home network to the Internet. You need to ensure that ICS is enabled on the connection that connects your home network to the Internet. As a result, the home network connection appropriately allocates TCP/IP addresses to its own users, the shared connection connects your home network to the Internet, and users outside your home network are not at risk of receiving inappropriate addresses from your home network. By enabling ICS on a connection, the ICS computer becomes a Dynamic Host Configuration Protocol (DHCP) allocator for the home network. DHCP distributes TCP/IP addresses to users as they start up. If Internet Connection Sharing is enabled on the wrong network adapter, users outside your home network might be granted TCP/IP addresses by the home network DHCP allocator, causing problems on their own networks.

The ICS feature is intended for use in a small office or branch office networking environment, where network configuration and the Internet connection are managed by the computer running Windows 2000 (where the shared connection resides). It is assumed that on its network, this computer is the only connection and gateway to the Internet, and that it sets up all internal network addresses. The Internet Connection Sharing feature does not work if the network contains DHCP or DNS servers.

The following protocols, services, interfaces, and routes shown in Table 21.6 are configured when you enable Internet Connection Sharing.

Table 21.6 Internet Connection Sharing Settings

To use the Internet Connection Sharing feature, users on your branch office network must configure TCP/IP on their local area connection to obtain an IP address automatically. For more information about configuring Internet Connection Sharing, see Windows 2000 Help.

Note

For branch office clients to access the Internet, the computer with Internet Connection Sharing (ICS) enabled on it must either have an active connection, or the shared connection must have on-demand dialing enabled.