Collision
Collision definition
A collision is a situation when two or more data packets try to occupy the same network channel at the same time. This leads to them interfering with one another. Collisions happen in a shared medium network, such as an Ethernet network, where devices have equal access.
Collisions in networking are largely associated with the Carrier Sense Multiple Access with Collision Detection (CSMA/CD) protocol. Here, all network nodes listen to the traffic on the line and only send data when no other traffic is detected. If several nodes send data at the same time, a collision is detected, and all nodes stop transmission for a random period before attempting again.
Collisions are a normal part of shared medium network operation. Still, high collision rates signal a problem with network design or configuration. For example, there may be too many hosts in a single collision domain or insufficient network bandwidth for the volume of traffic. Modern networking technologies like switching and full-duplex operation have reduced the impact of collisions in today’s networks.
See also: data packet, packet loss
Collision types
- Single collision domain. This is the simplest type of collision, occurring when several devices attempt to send data on the same network segment at the same time.
- Multiple collision domains. This type of collision occurs in larger networks with several segments (collision domains). If devices in different segments attempt to send data at the same time, it could lead to a collision on the network backbone (the primary data transmission line connecting these segments).
Network issues caused by collisions
- Network performance degradation. Frequent collisions can slow down network performance as devices often have to stop, wait, and try resending packets.
- Data loss. Collisions can lead to lost or damaged packets, requiring retransmission and using extra network resources.
- Network instability. In extreme cases, a high collision rate could make a network unstable or unusable, leading to significant business impact.