In a past Cisco CCENT accreditation exam tutorial, all of us talked about broadcasts and the potential associated with a broadcast thunderstorm. (If you overlooked that one, pay a visit to my website’s Lessons section. ) Inside of today’s tutorial, most of us discuss many different commonplace network devices and how they aid to limit broadcast propagation – or in some cases, how they do not help!
In the “do not help” department, most of us find hubs in addition to repeaters. These two devices operate with Layer 1 associated with the OSI model (the Physical layer), and their single purpose is in order to strengthen the electric powered signals sent above the cable. They will not have anything in order to do with turning or routing, plus they never help to limit contacts. (A hub is actually just a repeater with increased ports. )
One the other side of the coin end associated with the spectrum, all of us have routers. Routers operate at Coating 3 of the OSI model (the Network layer), plus by default routers do not forwards broadcasts. They can certainly be configured to “translate” certain broadcast types into unicasts, but you’ll understand more about that will in your CCNA scientific studies.
Since routers carry out not forward broadcasts, there’s a belief that routers have got nothing to carry out with broadcasts. Routers can indeed generate messages, and so they can acknowledge them – although they will never frontward them. That’s a great important distinction.
Among these two extreme conditions, we find switches. Fuses operate at Part 2 of the OSI model (the Data Link layer), and the arrears behavior of the switch is to be able to accept a transmit and forward this out every some other single port in that switch except the port that first received the particular broadcast.
If that feels like a lot of broadcast forwarding, it is! If we come with an 80-port switch then one port receives a transmitted, by default a copy of that transmitted will probably be forwarded out the other 79 ports. More than likely, not necessarily all of individuals hosts connected to be able to those switchports need to see that broadcast, and mailing unnecessary broadcast outcomes in an unnecessary use of network resources, particularly band width.
Luckily for us, we have a way to configure a Cisco switch to limitation which ports acquire that broadcast, plus we’ll take the look at of which method in typically the next installment regarding my Cisco CCENT certification exam guide series!
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