Network bridges are devices that allow multiple LANs to communicate with one another, expanding their reach beyond that of a single network. They inspect incoming traffic from network devices like computers, phones, printers, and routers, then decide whether to forward that traffic or discard it.

There are seven layers to every network, from the hardware devices used to transmit information to applications. The Open Systems Interconnection (OSI) diagram maps these layers out visually. Network bridges are on the second, or data-link, layer of the OSI model.

What helps the bridge decide where to route incoming traffic is the information being communicated by each device trying to send and receive data on the network. That can include what protocol a device is using to connect, as well as that device’s Media Access Control (MAC) address, also referred to as a hardware or physical address.

The main purpose of a network bridge is to allow more devices to access a network without what’s known as a “collision domain” happening. Collision domains are when two or more devices on the same network try to transmit data at the exact same time, causing problems.

If a network is too large, a network bridge can be used to segment it into smaller networks. If, for example, 30 devices were connected to one network, a bridge could decrease the likelihood of a collision happening by partitioning that into two networks of 15 devices each.

When a device transmits for the first time on the network, its MAC address is added to the forwarding table for the network bridge to reference later. Once every device’s MAC address has been added to the table, the network bridge can efficiently route traffic.

Do I Need a Network Bridge?

Most people probably don’t need to use a network bridge. They usually don’t need to connect an excessive number of devices to their network or need a physical coverage area wider than their home.

If you have a lot of devices that need to connect to your wireless LAN, as in a large office with multiple computers/routers/etc., or need to connect multiple LANs a network bridge could be useful. If your network is especially large, a network switch might be a better option.

Types of Network Bridges

A network bridge can support multiple connection types depending on the protocol used. There are Wi-Fi to Ethernet bridges, Wi-Fi to Bluetooth bridges, and Wi-Fi to Wi-Fi bridges. Each of these can be used for a specific purpose. For example:

• A Wi-Fi to Wi-Fi bridge can be used to set up wireless access points like the one in your local coffee shop.
• Bluetooth to Wi-Fi bridges are used to connect mobile devices using Bluetooth at home or at the office.
• Ethernet to Wi-Fi bridges let ethernet devices access a wireless network, and are especially useful for older devices that don’t have Wi-Fi connectivity.

Network Bridges vs. Other Network Devices

Several other devices can be used to build a LAN in addition to network bridges. Some of them serve similar functions, but none are exactly the same.

Repeaters, for example, look a bit like bridges but their only function is to expand an LAN’s coverage area by forwarding traffic along. They can’t route traffic or divide a network. Some network bridges can also act as repeaters.

Switches perform much the same function as a bridge, with some variations. They have more physical ports than a bridge, usually four or more, so switches are sometimes called multiport bridges. They use ASICS (Application Specific Integrated Circuits) to route traffic, while a bridge uses software. Switches can route traffic using three methods: store and forward, cut-through, or fragment-free. Bridges just use store and forward.

Routers are more “intelligent” than a network bridge in that they can route traffic dynamically. They can be configured to filter certain data packets for greater network security. Routers, in conjunction with gateways, operate as the “backbone” of the internet and thus have the ability to deal with multiple network addressing frameworks and data packet sizes. They also have a “bridge mode” you can use when there’s a spotty connection. If you’re looking for ways to improve your home Wi-Fi that don’t require extra money, we’ve got a few tips you can try for free before you decide to add a network bridge to your home LAN.