Time
12 hours 41 minutes
Difficulty
Advanced
CEU/CPE
13

Video Description

We're almost at the summit of the OSI model as we examine layers 5 and 6, otherwise known as the session and presentation layers respectively. The session layer is responsible for establishing connections between applications that reside up at layer 7. It uses a negotiation procedure or handshake to setup, transfer data (maintenance), and tear down the connection or session. The terms connection and session are often used interchangeably. The presentation layer handles file-level encryption, compression, and formatting duties. Universal file formats such as gif, jpeg, and mp3 are defined at layer 6. This is a brief video and the key point to remember, and one that is certainly testable, is that no protocols exist at layer 6. This is striking since even the layer 1 physical layer has protocols as they relate to media such as cables and wiring.

Video Transcription

00:04
Now we're up to layer five this session layer and this layer is responsible for establishing a connection between two applications. So when you have that client piece connecting to a server piece that session layer stuff, So for instance, you know, we talked about S S L T L s
00:22
being layer for and
00:24
you know that's true. If you're gonna put it at a specific layer for a test, right, And if you have to put it at one layer or another, Layer four is where I belong. However, the truth of the matter really is that SSL functions across laters four through seven,
00:41
and you can certainly see a session with your piece. When you have
00:45
the Web browser connecting to the Web server, that element is session layer. That's a session with your connection, eh? So we would look for the phrase of set up maintenance and tear down of a connection. They really could also say, set up maintenance and tear down of a session.
01:02
And then many people would say, almost like getting chewed session that seemed too obvious.
01:07
Sometimes it seems so obvious because it's obvious because it's true. So don't let that throw you off.
01:12
So down at the bottom, you can see TCP does some session oriented stuff. That's true. That whole negotiation, the handshake process. But again, things really were not designed to go in a nice, neat little box. But for a test, we have to put them in the nice, neat little box. So of course T c p u t p. You're gonna be later for
01:33
and Session Lee or set up maintenance and tear down
01:36
of the connection.
01:38
Now we move up to lay your six and let your six is responsible for three things formatting, encryption and compression. So when we talk about compression, of course, we're removing any sort of redundancy in the file so that it takes less time, perhaps too
01:53
transmit across the network or depending on how it is compressed,
01:57
taking up less space on the hard drive. We talk about encryption and the thing about encryption to keep in mind his encryption happens across many layers. You know it. Layer one. You have hardware based encryption. Layer three. You have I p sec player for you. Of s s l N t l s.
02:15
Lay your six. We're talking about the file level encryption. So within the operating system,
02:21
encrypting a file that's the type of encryption. Layer six now. Ah, compression encryption and then also formatting, making sure we're in a universe reversal format so that I can create an email on a Mac and send it to you on your PC and
02:38
and everything still in the same format. But we're also talking about things like Jeff Files, J Pegs,
02:44
MP three's and NP four's The Formatting that's necessary for those elements. Those air all lay your six elements, also testable.
02:53
This is the only layer of the S I model that does not have a protocol, and that's definitely question that they like to ask. Or that would be very appealing to ask, for instance, if I wrote the exam and you know, even down a layer one even now, at the physical layer, we have protocols for wiring and other specifications,
03:14
so lay your six has no
03:15
protocols associating with it. Think about the three things formatting compression and encryption

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