busstopologi

Bus topology, or busstopologi in some languages, is a network arrangement in which all devices connect to a single central communication line, called the bus or backbone. The shared medium carries signals in both directions, and every device on the line can hear transmissions. In traditional Ethernet implementations using a coaxial cable, data is placed on the bus and travels to all nodes, with only the intended recipient paying attention to the frame while others ignore it.

Technical wiring and signaling rely on the backbone being a single, continuous medium. To prevent signal reflections that can cause communication errors, terminators are placed at both ends of the bus. Many early Ethernet networks used coaxial cables such as thicknet or thinnet. Access control is typically achieved with a shared medium protocol, commonly CSMA/CD, where devices listen before transmitting and collisions are detected and handled by a backoff procedure.

Advantages of bus topology include straightforward installation and relatively low cable costs for small networks, as well as easy extension by tapping into the backbone. However, as more devices are added, performance degrades due to an increasing likelihood of collisions. A fault or damage to the backbone can bring down the entire network, and troubleshooting can be challenging because traffic is shared and not easily isolated. Cable length and the number of connected devices are also limited by electrical constraints.

Today, bus topology is largely obsolete in new Ethernet deployments, which favor star topologies using switches. It remains of historical importance for understanding early local area networks and is sometimes encountered in educational settings or legacy installations.