The Network Bridge is a software component found in Windows XP that lets you connect two network segments together. If you have a dual-homed server, that server would require the use of a network bridge to connect computers talking to one NIC card to the computers talking to the other. The Network Bridge functions in place of a traditional bridge or router by providing a means in software to create a named Bridge Connection that can be managed. The Network Bridge allows you to create a single IP subnet for an entire network, with attendant simplification of addressing and name resolution. The Network Bridge allows for connections between different types of media, and provides the means for forwarding packets when different protocols are used. A single bridge is installed on Windows XP, but that bridge can support multiple connections, both physical (modem or wireless cards, for example), or logical.
An administrator can create a network bridge in Windows using the Network Connections folder accessed from the Connect To menu (Show All Connections). In the LAN or High-Speed Internet section, right click on any connection that you wish to add to the bridge and select the Bridge Connections command. Then click on Properties, the General tab and in the Adapters section, check the boxes of each adapter to be added, and exit. To remove the connection at a later time, perform the same operation and uncheck the appropriate connection boxes.
The bridge requires two or more connections to be added to be active, and Internet Connection Sharing (ICS) or Internet Connection Firewall (ICF) connections are not eligible. Connections can be bridged suing any of the following media: Ethernet, IEEE-1394 (Firewire; currently for IP4 only), wireless (WiFi), and home phoneline adapters (HPNA). A security risk occurs when you attempt to bridge an Internet connection to an internal LAN connection when you don't have ICF or ICS enabled (these features are not available in 64 bit Windows XP yet.
Barrie Sosinsky is president of consulting company Sosinsky and Associates (Medfield MA). He has written extensively on a variety of computer topics. His company specializes in custom software (database and Web related), training and technical documentation.