Protokollbridges

Protokollbridges, or protocol bridges, are network devices or software components that connect two or more networks and enable communication by bridging across protocol boundaries. In its most common sense, a protocol bridge is a layer-2 device that forwards frames between network segments according to MAC addresses, potentially handling multiple data-link protocols. More broadly, the term also covers devices that translate or encapsulate data to allow communication between networks using different higher-layer protocols.

Two main forms exist: (1) bridging (or learning bridges) that preserve the original protocol and operate at the data link layer; (2) protocol translators or gateways that perform protocol conversion, often operating at higher layers to enable end-to-end communication between incompatible systems (for example connecting Ethernet/IP networks to fieldbus or other industrial protocols).

Bridges build forwarding tables by observing source addresses, thereby learning where devices are located and reducing unnecessary broadcasts. They can segment collision domains, improve performance, and maintain transparency for IP within each segment. When translating protocols, they must map data units, addresses, and semantics across the boundaries, sometimes introducing latency and requiring careful synchronization.

Used in enterprise networks to connect LANs with different media, in network migrations, and in industrial environments to connect legacy fieldbuses to IP networks via gateways. In software-defined and virtualization contexts, virtual bridges connect virtual machines to physical networks and to each other.

Distinguish bridges from routers and gateways; bridges do not route IP networks by default, whereas gateways translate protocols. Security, performance, and compatibility are key considerations when deploying Protokollbridges.