In this video, Anthony Sequeira walks you through some key facts regarding the OSI model.
Remember, the OSI model breaks down networking functions into seven layers:
- Application – high end protocols for network applications; examples inlcude HTTPS and FTP
- Presentation – data represenations like JPG and ASCII
- Session – this layer maintains sessions between end stations
- Transport – this layer is where we have segments (the PDU term); data can be sent with reliability or unreliability using protocols at this layer
- Network – this layer is responsible for routing packets (the PDU term) throughout the network and beyond; it is at this layer where IP address information (source and dest) is encapuslated
- Data link – this layer takes care of encapsulating in addressing information (and other important info) as required to send data in the network; in an Ethernet network, this includes the encapsulation of source and destination MAC address information; the PDU term at this layer is frame
- Physical – this includes the stuff that sends the bits over the wire and the wire itself; it also includes things we cannot see with our eyes, for example, the radio frequency spectrum used to carry data in WiFi networks; here the PDU is termed simply bits
Learn to Love It…
The OSI model gets a really bad reputation in the world it seems. This is not some silly acedemic thing made up just to torture aspiring networking or cyber security students, it is a model that you can use throughout your entire career to help you learn new technologies, and to help you pass a crap ton of exams! Oh – and you will also most likely use it every time you are troubleshooting a network related problem.
In fact, you really should consider using it every time because you can avoid some really, really potentially embarrasing moments in your career. You know, like having someone trbleshoot for hours at the application layer, when the iossue was the physical layer all along. You know, the classic, it was not plugged in issue!
The OSI model should be studied, debated, loved, revered, made fun of, for many many decades to come.
Thanks as always for stopping by and reading and or watching.
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