An Ethernet network bridge is a device which connects two different local area networks together. Both networks must connect using the same Ethernet protocol. Bridges can also be used to add remote computers to a LAN. Many bridges can connect multiple computers or other compatible devices with or without wires.
There are two common types of Ethernet bridges. One is the wi-fi bridge, which is used to connect a computer to a network without wires and without a network adapter. Another type is the powerline Ethernet bridge, which uses a building's electrical system to connect remote computers.
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Bridges use the Data Layer (Layer 2) of the Open Systems Interconnection (OSI) Reference Model to find computers on a network. They find devices using Media Access Control (MAC) addresses, which are hardware addresses. However, they can't find Internet protocol (IP) addresses as network routers can. Network routers operate at Level 3 of the OSI model, or the Network Layer.
There are many devices which act both as a bridge and as a router. These are sometimes referred to as "brouters." Bridges may also function as access points. Wi-fi bridges are most commonly used to connect wireless devices to a wired Ethernet network. They come in Wireless B, G and N standards, just like wireless routers and access points. The powerline Ethernet bridge plugs into an electrical wall socket. It turns the electrical wiring in your home or office into network cable.
Wireless bridges are typically less expensive and easier to install than routers. However, if the computer you're trying to connect isn't too far away from the network router, an access point or bridge and access point combination may be better. The wireless bridge and powerline bridge both obviate the necessity of stringing Ethernet cable through walls or an attic. They both simplify network installation significantly. You can also use an Ethernet bridge to connect an IP telephone or set top box to your network. You can also use the wi-fi bridge to put your Ethernet scanner, printer or digital camera on your wireless network.
Routers can use IP addresses to determine where data needs to go. Bridges, on the other hand, use MAC hardware addresses to send data. Thus routers are more efficient and intelligent than bridges. Routers also offer other features bridges typically don't have, such as built-in firewalls, network storage links, Internet access restrictions and MAC address filtering. Always use a router and access points whenever possible to build your local area network.