Network Bridge overviewNetwork Bridge provides an inexpensive and easy way to connect local area network (LAN) segments. A LAN segment is a single section of network media that connects computers. For example, suppose you have three computers: computer A, computer B, and computer C. Computer A has two Ethernet network adapters, and computers B and C have one Ethernet network adapter each. An Ethernet cable connecting A to B creates one LAN segment. Another Ethernet cable connecting A to C creates another LAN segment.

Traditionally, if you want a network with more than one segment, you have two options: routing or bridging. IP routing is a common solution for connecting network segments. However, to set up IP routing you either must buy hardware routers or set up the computers at the junctions between segments to operate as routers. IP routing requires difficult IP addressing configuration for each computer on each network segment, and each network segment must be configured as a separate subnet. IP routing is a good solution for large networks, where scalability is important, and where there is an experienced staff to configure and maintain the network. A bridge does not require difficult configurations, but you must purchase additional hardware bridges. Neither of these options are ideal if you have a home or small office network, do not want to purchase expensive bridging hardware, and do not have experienced staff to administer an IP routing network.

With Network Bridge, you can connect LAN segments by selecting the appropriate network connection icons and clicking Bridge Connections. Equally easily, you can enable the bridge and add connections to it. The network bridge manages your network segments and creates a single subnet for the entire network. There is no configuration required, and you do not need to purchase additional hardware such as routers or bridges. IP addressing, address allocation, and name resolution is easy to do in a single subnet IP network.

The network bridge can create connections between different types of network media. In a traditional network, if you are using mixed media types you need a separate subnet for each type of media, and packet forwarding is required for each one of the network's multiple subnets. Packet forwarding is required because different protocols are used for different types of media. Network Bridge automates the configuration required to forward information from one type of media to another.

Only one bridge can exist on a computer running Windows XP, but you can use it to bridge as many network connections as the computer can physically accommodate. For information about creating a network bridge, see Bridge Connections.

Spanning tree algorithm
Network Bridge uses the IEEE spanning tree algorithm (STA) to establish a loop-free forwarding topology. When there are multiple paths in a bridged network, loops can form and the simple forwarding rules of a bridge can cause forwarding storms, a condition in which the same frame is relayed endlessly from one bridge to another. STA provides an automated mechanism to selectively disable bridge forwarding on individual ports as necessary to ensure that the forwarding topology is loop-free. You do not need to configure Network Bridge for the spanning tree algorithm.