Cisco CCNA – CCENT Certification Exam Training – Broadcasts, Hubs, Routers, And Switches

In a prior Cisco CCENT certification examination tutorial, we talked about broadcasts and the probable of a broadcast storm. (If you missed that 1, check out my website’s Tutorials area.) In modern tutorial, we will talk about a number of various common network devices and how they assistance to limit broadcast propagation – or in some conditions, how they do not enable!

In the “do not help” office, we’ll come across hubs and repeaters. These two gadgets work at Layer 1 of the OSI design (the Bodily layer), and their sole intent is to strengthen the electrical alerts despatched more than the cable. They do not have anything to do with switching or routing, and they do not aid to restrict broadcasts. (A hub is generally just a repeater with a lot more ports.)

On the other conclusion of the spectrum, we have routers. Routers run at Layer 3 of the OSI design (the Community layer), and by default routers do not ahead broadcasts. They can be configured to “translate” specified broadcast types into unicasts, but you can expect to discover far more about that in your CCNA scientific tests.

Considering that routers do not forward broadcasts, there is certainly a misconception that routers have almost nothing to do with broadcasts. Routers can in fact deliver broadcasts, and they can settle for them – but they will not ahead them. Which is an critical difference.

In between these two extremes, we obtain switches. Switches work at Layer 2 of the OSI design (the Information Hyperlink layer), and the default conduct of a change is to acknowledge a broadcast and forward it out each individual other solitary port on that swap except the port that initial gained the broadcast.

If that appears like a large amount of broadcast forwarding, it is! If we have an 80-port change and one port gets a broadcast, by default a copy of that broadcast is likely to be forwarded out the other 79 ports. Most likely, not all of those people hosts related to those people switchports require to see that broadcast, and sending avoidable broadcast success in an unnecessary use of network sources, significantly bandwidth.

Luckily for us for us, there is a way to configure a Cisco change to restrict which ports obtain that broadcast, and we are going to choose a search at that strategy in the upcoming installment of my Cisco CCENT certification test tutorial series!