What is Network Bridge?

Network bridges operate at Layer 2 (Data Link) of the OSI model, forwarding Ethernet frames between segments based on MAC address tables. They learn which devices are on which port by examining source MAC addresses of incoming frames. Bridges extend network reach while filtering traffic — frames destined for the same segment are not forwarded. In virtualization, software bridges (Linux bridge, Open vSwitch) connect virtual machines to physical networks. Docker uses bridge networks by default for container communication. Bridges differ from routers (Layer 3, IP-based forwarding) and switches (modern multi-port bridges with hardware acceleration).