In the context of computer networks, a bridge (bridge) is a device that connects two or more network segments, operating at the data link layer of the OSI model (layer 2).

Its main purpose is to filter network traffic, transmitting or blocking data packets (frames) based on the source and destination MAC (Medium Access Control) addresses. By doing so, it helps manage traffic on a network, reduce congestion, and increase network efficiency by logically segmenting it.

Main Functions of a Bridge:

• Traffic Filtering: Decides whether a data frame should be forwarded or discarded based on the source and destination MAC address. If the frame is destined for a device on the same network segment, the bridge blocks it so as not to resend it unnecessarily. If the destination is on a different segment, the bridge forwards the frame to that segment.
• Creation of Network Segments: Bridges can divide a larger network into smaller segments, reducing the collision domain (area where packet collisions can occur on an Ethernet network) and improving overall network performance.
• MAC Address Learning: A bridge has the ability to learn and store the MAC addresses of the devices connected to each of its ports. This allows you to make smart decisions about where to forward data frames.

Bridge Types:

• Local Bridges: They connect network segments within the same building or geographic area.
• Remote Bridges: They can connect network segments that are geographically separated, using telecommunications links.
• Transparent: They are invisible to devices on the network; The devices do not need to be configured to use them.
• Non-Transparent: They require special configurations on network devices to operate.

Use in Modern Networks:

In modern networks, bridge functionality is often integrated into other network devices, such as switches and routers. In fact, a switch can be considered a multi-port bridge with advanced traffic filtering and management capabilities.

Bridge implementation has become more sophisticated over time, offering additional features such as support for Virtual LANs (VLANs) and other network control protocols.

In home and small business networking environments, the bridge feature is also often found in wireless access points and routers, where it is used to connect different network media (for example, wired and wireless) or to expand the network.