In a previous Cisco CCENT certification exam tutorial, all of us discussed broadcasts and even the potential involving a broadcast storm. (If you missed that one, pay a visit to my website’s Courses section. ) In today’s tutorial, we’ll discuss many different commonplace network devices in addition to how they assist to limit broadcast distribution – or in some instances, how they perform not help!
Inside the “do not really help” department, most of us find hubs plus repeaters. These a couple of devices operate with Layer 1 of the OSI model (the Physical layer), and their sole purpose is in order to strengthen the electric powered signals sent more than the cable. They will not have anything in order to do with turning or routing, and even they do not help to limit contacts. (A hub is simply just a repeater with additional ports. )
One the other side of the coin end involving the spectrum, many of us have routers. Routers operate at Part 3 of the OSI model (the Network layer), plus by default routers do not ahead broadcasts. They can be configured to be able to “translate” certain transmitted types into unicasts, but you’ll find out more about that will inside your CCNA scientific studies.
Since routers carry out not forward shows, there’s a misconception that routers have nothing to conduct with broadcasts. Routers can indeed generate broadcasts, and so they can take them – but they will not likely forwards them. That’s a great important distinction.
Among these two opposites, we find switches. Switches operate at Coating 2 of the OSI model (the Data Link layer), and the default behavior of a new switch is to accept a transmitted and forward this out every some other single port about that switch besides the port that first received typically the broadcast.
If that will feels like a whole lot of broadcast forwarding, it is! When we have an 80-port switch and something slot receives a broadcast, by default a duplicate of that send out will probably be forwarded out the other 79 ports. Probably, not all of these hosts connected in order to those switchports need to see that broadcast, and sending unnecessary broadcast effects in an unwanted use of network resources, particularly bandwidth.
Luckily for us all, there exists a way to be able to configure a Gresca switch to limitation which ports obtain that broadcast, plus we’ll take some sort of look at that will method in the next installment of my Cisco CCENT certification exam tutorial series!
Chris Bryant, CCIE #12933, is usually the owner regarding The Bryant Edge, home of totally free Barullo CCENT Certification and even CCNA Certification Assessment tutorials, The Ultimate CCNA Study Package, plus Ultimate CCNP Examine Packages.
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