Collision & broadcast domain

 

Collision domain

A collision domain is that the part of a network where packet collisions can occur. A collision happens when two or more devices send a data at same time on the shared network segments. The packet crash and both devices must send the packet again, which decrease network efficiency. Collisions are happens in hub environment, because every p0rt on a hub is in same collision domains. Contrast, each port on a bridges, a switches or routers is in a separate collision domain.

The below example illustrates the collision domains:

We have 6 collision domain in the above example .

NOTE
Remember, every port on a hub is in the same collision domain. Each port on a bridges, a switches or routers is in a separate collision domains.

Broadcast domain

A broadcast domain is a domain wher a broadcast is forwarded. A broadcast domain contain every device that can reach each other at the data link layer by using broadcast. All ports are on hubs or a switches are by default in the same broadcast domain. Every port on a router are in the different broadcast domains and router do not forward broadcast from one broadcast domain to another broadcast domain.

The below example explain the concept:

In the above picture we have three broadcast domain, And every ports on a hub or a switch are on the same broadcast domain, and every ports on a router are in a different broadcast domain.