Managing Collisions

Collisions occur on a network when two or more networked devices transmit data at the same time. The result is that the data collides, becomes corrupted, and needs to be re-sent. If these collisions keep occurring, the network slows down and can eventually impact network users. Media Access Control (MAC) techniques can help prevent collisions from occurring. Two commonly used MAC methods include Collision Sense Multiple Access/Collision Detection, or CSMA/CD, used with wired Ethernet networks and Collision Sense Multiple Access/Collision Avoidance, or CSMA/CA, used with 802.11 wireless networks.

The more devices that connect to an Ethernet network, the more likely it is that collisions will occur on the network. In other words, the more devices you add to an Ethernet network, the slower, exponentially, the network will become. This decreasing of performance has driven improvements in the structure of how Ethernet networks. Improvements include the substitution of older hubs with new, high-performance Ethernet switches and the reduction of broadcast-intensive applications.

Collisions can mostly be avoided by using switches instead of hubs. Switches enable for the segmentation of Ethernet networks into smaller collision domain. Whereas the use of a hub creates a large single collision domain, each port on a switch represents a separate collision domain. The switch can provide full-duplex communication to the node/nodes connected to that port. In a switched network, systems do not need to use collision detection and can just transmit without hesitation.

TIP:Remember that a switch reduces the need for a contention-based network environment because the switch ports break down the network into smaller collision domains. The smaller the collision domain, the fewer collisions that occur.