Defining Collision Domains Cisco CCNP Exam Tutorial

Defining Collision Domains Cisco CCNP Exam Tutorial
A collision domain is an area in which a collision can occur. Fair , but what "collision" are they talking about here? we are talking about collisions that occur on CSMA/CD segments, or Carrier Sense Multiple Access with Collision Detection. If two hosts on an Ethernet segment transmit data at exactly the same time, the data from the two hosts will collide on the shared segment. CSMA/CD exists to lessen the chances of this happening, but collisions can still occur. To lessen the chances of collisions occurring, they may decide to generate multiple, smaller collision domains.

CCNA exam success depends on mastering the fundamentals, & two important fundamentals are knowing exactly what the terms "collision domain" & "broadcast domain" mean. In this free Cisco tutorial, we'll take a look at the term "collision domain" & how a collision domain is defined.

To generate smaller collision domains, we'll need to introduce some type of networking tool into this example. Hubs & repeaters have their place as far as extending the reach of a network segment & cutting down on attenuation, but these OSI Layer two devices do nothing to define collision domains. they could connect each host into a separate port on a hub (a hub is basically a multiport repeater) & we'd still have two single collision domain with four hosts in it.

Let's say they have four hosts on a single Ethernet segment. The entire segment is a collision domain; any data sent by two of the hosts can collide with data sent by any of the other hosts. they have two collision domain containing four devices.

Passing the CCNA is all about knowing the details of how things work, & knowing CSMA/CD theory & how to define collision domains is two of the plenty of details you've got to master. In the next part of this CCNA tutorial, we'll take a look at broadcast domains, & how defining broadcast domains in the right places can dramatically cut down on unnecessary traffic on your network.

The most common & most effective way to generate multiple collision domains is to use a switch. If they connect each of these four hosts to their own separate switch port, they would now have four separate collision domains, each with two host; each switch port actually acts as a single collision domain, making collisions between these four hosts impossible.