Bridges - Basic Hardware Component

A bridge device filters data traffic at a network boundary. Bridges reduce the amount of traffic on a LAN by dividing it into two segments.A network bridge connects multiple network segments at the data link layer (layer 2) of the OSI model. Bridges do send broadcasts to all ports except the one on which the broadcast was received.

Bridges inspect incoming traffic and decide whether to forward or discard it. Bridges serve a similar function as switches, that also operate at Layer 2. Traditional bridges, though, support one network boundary, whereas switches usually offer four or more hardware ports. Switches are sometimes called "multi-port bridges" for this reason.

Bridges come in three basic types:
- Local bridges: Directly connect local area networks (LANs)
- Remote bridges: Can be used to create a wide area network (WAN) link between LANs. Remote bridges, where the connecting link is slower than the end networks, largely have been replaced with routers.
- Wireless bridges: Can be used to join LANs or connect remote stations to LANs

Today, bridges are slowly but surely falling out of favor. Ethernet switches offer similar functionality; they can provide logical divisions, or segments, in the network. In fact, switches are sometimes referred to as multi-port bridges because of the way they operate.