Collision and Broadcast Domains

Both broadcast and collision domains are inherent characteristics of network devices during transmission of packets from one node to another. Therefore, they need to be managed properly to avoid congestion and efficiently utilize network resources.

In broadcast domain, the set of all network devices receive broadcast frames or messages originating from any of the devices within the segment under consideration. It includes all of the hosts that a broadcast frame transmitted by a single host can reach.

Examples: switch is one broadcast domain if VLAN is not configured, but it will have as many collision domains as the number of switch ports. This means, switch is capable of handling broadcast domains, which is unlike hubs, repeaters, etc. Routers are also capable of creating broadcast domains.

A collision domain, on the other hand, is a network segment or subnet with two or more devices sharing the same bandwidth. It is the segment of the network where packet collision may occur if two nodes attempt to communicate at the same time to grab a network service.

Collision domain is unpleasant issue, may cause competition for a resource, and thus may cause collisions. Examples: Hubs have one broadcast domain and one collision domain. Ethernets are single collision and broadcast domain devices but uses CSMA/CD to handle collisions. However, similar to switches, bridges isolate collision domains to realize efficient resource utilizations.