Collision domain

Wifi hidden station problem

Collision domain

A collision domain is a network segment connected by a shared medium or through repeaters where simultaneous data transmissions collide with one another. In a collision domain, only one device can successfully send data at a time, and if two devices attempt to send data simultaneously, a collision occurs, causing the data to be corrupted and requiring retransmission.

Characteristics

Collision domains are a fundamental concept in Ethernet networking, particularly in networks using Carrier Sense Multiple Access with Collision Detection (CSMA/CD). In such networks, devices listen to the network before transmitting to avoid collisions. If a collision is detected, devices stop transmitting and wait for a random period before attempting to resend the data.

Impact on Network Performance

The size of a collision domain can significantly impact network performance. Larger collision domains have a higher likelihood of collisions, leading to increased retransmissions and reduced network efficiency. To mitigate this, network devices such as switches and routers are used to segment collision domains, thereby reducing the number of devices that share the same domain.

Reducing Collision Domains

- **Switches**: Unlike hubs, which extend collision domains, switches create separate collision domains for each connected device. This isolation allows multiple devices to communicate simultaneously without collisions. - **Routers**: Routers also segment collision domains by forwarding data between different networks, ensuring that collisions in one domain do not affect another.

Historical Context

In early Ethernet networks, bus topology and star topology with hubs were common, leading to large collision domains. The advent of switches and the transition to full-duplex communication have largely eliminated the problem of collisions in modern networks.

Related Concepts

- Broadcast domain - Network topology - Ethernet frame - Media Access Control - Network segment

See Also

• Carrier Sense Multiple Access with Collision Detection
• Network switch
• Router
• Hub
• Broadcast domain
• Ethernet