Learn How to Use a Bridge to Expand Your Local Network

Pair two local area networks to work as a single network

Shanghai bridge
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A network bridge joins two otherwise separate computer networks to enable communication between them and allow them to work as a single network. Bridges are used with local area networks (LANs) to extend their reach to cover larger physical areas than the LAN can otherwise reach. Bridges are similar to—but more intelligent than—simple repeaters, which also extend signal range.

How Network Bridges Work

Bridge devices inspect incoming network traffic and determine whether to forward or discard it according to its intended destination.

 An Ethernet bridge, for example, inspects each incoming Ethernet frame including the source and destination MAC addresses—sometimes the frame size—when making individual forwarding decisions. Bridge devices operate at the data link layer of the OSI model

Types of Network Bridges

Bridge devices exist for Wi-Fi to Wi-Fi, Wi-Fi to Ethernet, and Bluetooth to Wi-Fi connections. Each is designed for specific kinds of networking.

  • Wireless bridges support Wi-Fi wireless access points.
  • Wi-Fi to Ethernet bridges allow connections to Ethernet clients and interface them to a local Wi-Fi network, which is useful for older network devices that lack Wi-Fi capability.
  • A Bluetooth to Wi-Fi bridge supports connections with Bluetooth mobile devices that have proliferated in homes and offices in recent years.

Wireless Bridging

Bridging is especially popular on Wi-Fi computer networks. In Wi-Fi, wireless bridging requires that access points communicate with each other in a special mode that supports the traffic that flows between them.

Two access points that support wireless bridging mode work as a pair. Each continues to support its own local network of connected clients while additionally communicating with the other to handle bridging traffic.

Bridging mode can be activated on an access point through an administrative setting or sometimes a physical switch on the unit.

Not all access points support wireless bridging mode; consult the manufacturer's documentation to determine whether a given model supports this feature.

Bridges vs. Repeaters

Bridges and network repeaters share a similar physical appearance; sometimes, a single unit performs both functions. Unlike bridges, however, repeaters do not perform any traffic filtering and do not join two networks together. Instead, repeaters pass along all traffic they receive. Repeaters serve primarily to regenerate traffic signals so that a single network can reach longer physical distances.

Bridges vs. Switches and Routers

In wired computer networks, bridges serve a similar function as network switches. Traditionally, wired bridges support one incoming and one outgoing network connection, which is accessible through a hardware port, whereas switches usually offer four or more hardware ports. Switches are sometimes called multiport bridges for this reason.

Bridges lack the intelligence of network routers: Bridges do not understand the concept of remote networks and cannot redirect messages to different locations dynamically but instead support only one outside interface.