31 hours 29 minutes

Video Description

OSI Model 2 Layer 2 Data Link This lesson focuses on the second layer of the OSI model, which is the data link layer. Essentially, this layer is about access to a computer, access to a device. This is the layer that packages bits and data into frames. Frames are segments of data that we are pushing over layer 2 connectivity. It is a transfer from point to point and MAC addresses.

Video Transcription

next we have our laywer too Now are lait. Layer two is going to be our data link layer are later too. Is going to essentially be access to a computer access to our device now, whereas our layer one was a physical layer are layer two is going to package that bits
those physical bits, those physical impulses
it's going to package those into data and into frames were talking about frames were essentially thinking of segments of data that we're pushing over a layer to connective ity. So we think layer to we're thinking of frames and then we'll talk about a different term will use when we're talking about layer three.
So our layer to data link layer or acts we have access. It's going to be a transfer from point to point, whereas our further layers that we're gonna move on to with networking maybe the transfer of data across multiple networks are layer to connective ity is going to be from
point A to point B.
When we think about layer to, we also think about Mac addresses Now. Mac addresses stand for media access control addresses, and these were the addresses that are hard encoded into our network interface cards so that they have a globally worldwide, unique set of numbers that identify them.
We'll talk a little bit more about Mac addresses and how that
how they look in the later module. But all we really need to know right now is that Mac addresses are supposed to be unique to our network interface card. Different manufacturers are given, given different ranges of numbers to use, and they keep track of those. And when they manufacture their cards
to keep these numbers, keep these numbers
this this similar keep them unique per network interface card. If we had an environment where hypothetically, if we had two computers with with the same Mac address, we would end up with ah lot of different problems with connective ity with those two devices on our network. So these Mac addresses are unique,
so our transfer of our data when it gets to the point where it's sending to a specific Mac address
that's our layer to that's the point in our transfer. Where were we have layer to connective ity? If we are sending data from, say, a single computer to another computer directly through using its Mac address. We have that layer to data link layer. We can even throw a hub in there.
But as we've talked about in previous modules with hubs,
hubs don't really look at data packets. They don't really route or they don't really. They don't send data. According to I P addresses, most hubs or just dumb hubs, they really just act as repeaters. If we had other computers connected to this hub, this hub isn't going to care who who's connected to it.
It's going to send data. If we send it from computer a targeting computer, be
it's going to send it to computer see and computer D as well, and then just hope that they disregard it. So our hub would be a layer to device. Because it's not. It's not performing our Layer three networking layer functions. It's not routing. I. P is not routing at packets
by their I P address. It's not looking at I P address and addresses and moving those packets to designated designated computers. It's really just taking in the packet, and it's just sending it out to the different computers, even if it's if it's looking at a Mac address like we're using a switch.
We're still just using a layer to device there, just that data link player.
Think of our layer to our data link layer as if the truck is driving down. Has our package is driving down our street and it's the act of handing off the box to our particular house on our street. All we're really doing it. This data link layer is we're getting data from one point to another
providing that packaging of data and bits into frames. And when you think about layer to think about access thing about hubs or layer two switches or Mac addresses, and that's gonna be our at our laywer, too.

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Instructed By

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Anthony Harris
Systems Analyst and Administrator at SAIC