5.5
Collisions and Collision Domains in Shared Layer Environments
5.5.10 Segmenting collision domains
Although repeaters and hubs are useful, inexpensive networking devices, they extend collision domains. If the collision domain becomes too large, this can cause too many collisions and result in poor network performance.   The size of collision domains can be reduced by using intelligent networking devices that break up the domains. Examples of this type of networking device are bridges, switches, and routers. This process is called segmentation.

A bridge can eliminate unnecessary traffic on a busy network by dividing a network into segments and filtering traffic based on the station address. Traffic between devices on the same segment does not cross the bridge, and does not affect other segments. This works well as long as the traffic between segments is not too heavy. Otherwise, the bridge can become a bottleneck, and actually slow down communication.