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Collision domain

Collision domain definition

Collision domain refers to a network scenario where one device's data transmission can collide with another's due to them sharing the same network segment. In other words, it's an area of a network where packet collisions can occur if two devices send data at the same time.

The widespread adoption of network switches and routers has made a collision domain less relevant. However, the concept of a collision domain is not entirely outdated. It remains a useful framework for understanding network performance and troubleshooting network issues, even in modern, switch-based networks.

See also: fiber distributed data interface, load balancing router, multicast router, digital switch

How does collision domain work

When a device connected to the network wants to send data, it first checks whether another device is transmitting. If the line is clear, it sends its data. But if two devices begin transmitting at once, their data collides and becomes garbled. When this happens, both devices stop transmitting, wait for a random amount of time, and then try again.

Collision domain prevention

Switches, routers, and wireless networks all help avoid collision domains in different ways. A network switch creates a separate collision domain for each of its ports, a router does the same but goes even further by also creating separate broadcast domains, while a wireless network avoids collisions by using a different method of data transmission called CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance).