Time
31 hours 29 minutes
Difficulty
Beginner
CEU/CPE
30

Video Description

OSI Model Layer 4 Transport This lesson covers Layer 4, the transport layer of the OSI model. This layer provides us with management and control and also helps us to transfer data that we send and receive. It helps splits communications into different packages using either Transmission Control Protocol (TCP) or User Data Protocol (UDP). These protocols provide for either verification or no verification of delivery.

Video Transcription

00:04
next we have our layer four now are layer four is our transport layer, and it's going to provide us with management, control, management and control. It's going to also help us to transfer Data now are layer four. We don't want to confuse with our layer five our session layer.
00:21
Our Layer five provides more control over communication as faras
00:25
who can talk win, and it allows us to be able to send and receive messages without those messages conflicting or those messages starting to get job, All because we have multiple people talking at the same time. That's our layer five are Layer four is going to manage and control the data.
00:43
The pack in the data packets that we're focused on, the ones that were sending or that we're receiving is gonna manage those packets.
00:50
Our laywer for our transport port layer. It's going to help split our communications into different packages, and it's going to do this by using one of two different protocols gonna either use TCP or UDP. TCP stands for transmission control protocol.
01:07
U T P stands for user data grand protocol and
01:10
well, we've talked about these a little bit more are quite a bit more in depth as faras their exact details and certain frame sizes in some of our other modules. But our TCP and UDP, in a nutshell, provide for either no verification of delivery or verification of delivery receipt or no receipt.
01:30
If we think about T. C, P versus UDP, and we go back to our model shipping model here, T C P is going to be as if our our manufacturer here sent our package through verified male Senate through mail that requires our signature
01:48
and requires them to get back a receipt on delivery.
01:52
Ah, you tp. It's like if they dropped it in the mail and they didn't put a tracking code on it, there was no there was no tracking. There was no way for them to make sure that it got to us. That's our difference between TCP and UDP
02:02
now are different protocols either perform on TCP or UDP. We'll talk about a different protocols later, such as http https Sshh Secure shell SSL secure socket layer these air additional protocols. But all of our protocols are either
02:23
TCP or UDP based.
02:24
These are gonna be our basis for packaging up our data. These are going to be our basis for communications. And it's what's going thio transfer and manage our data and make sure that we're sending the package is in the right way. If we took, we can't take all of our data
02:43
and just send it all in one giant packet.
02:46
Our data isn't won't be manageable are our networks can't manage that. It would be very hard if we tried to send a one, get like, say, a one gig or two gig transfer of data from one computer to another and just tried to package it all in one packet. There's a
03:04
very good chance that that could be corrupted. There's a very good chance that,
03:08
well, none of our devices with support a packet size that large. So we essentially break down our files that were sending into these smaller packets that have different size limits. And TCP and UDP have their own different size limits and they have different asked parts to them that help to manage if they're getting receipt or not,
03:29
and
03:30
they also managed whether what order they're being reassembled and to make sure that they're being reassembled properly.
03:36
Our laywer for our transport layer provides management in control because they're using TCP because they help their managing T C P r UDP. TCP also provides making a new ability to make sure that packets are ordered in a proper way.
03:55
TCP helps to allow for re transmission of packets if they're bad, whereas UDP is going to be again a mess method of sending information, a method of sending these packages where it's just going to stream them.
04:12
Now you may be thinking, Well, why would I want to send you TP then? If there's no verification,
04:15
I would always want to send everything TCP right. Do I have control over that? Can I switch to send everything TCP on my computer Communications? Well, not really.
04:26
TCP and UDP have their functions and there are times when you would want to use UDP and their son and there are a lot of protocols on. We can't really go on our computer and manage what our protocols send over TCP are you T P.
04:40
But there are ways that we can manage that in our in our other settings, such as what protocols were using when we're sending information.
04:46
Um,
04:47
udp will be used for things like when we're streaming video or when we are making a Skype or a VoIP call. When we're making a call using Skype and we're streaming that data, we want it to be streaming over UDP because if we're using TCP,
05:04
that data is already requiring a lot of bandwidth.
05:08
We want to get the fastest response time possible. We don't want it to be choppy. We don't want it to be really fragmented. So we just our computer just says I'm just gonna push this and I'm not gonna verify before I send the next packet like TCP does. Because if I'm if I'm streaming a video with Skype or I'm making a phone call with Boyd
05:27
and I'm sending these packages,
05:29
I don't want my computer to send a little chunk and then wait until the other computer says it received it. Send another little chunk wait for my computer to say it received it, because I'm gonna have a very, very choppy conversation with somebody over Skype.
05:42
UDP is just going to say
05:44
I've got this and it has to get out. Our factory is on,
05:48
you know we have a product that is just flying off the shelves. We don't have time to have someone sit there and do all these tracking codes and make sure all the packages get to each individual house. We just need to put things on the truck and send them. And maybe one or two people don't get a package with you. D. P
06:06
Maybe I missed a packet or two and there's a little bit of fuzziness or there's a little bit of choppiness in the video,
06:12
but it's a lot less than if I had to sit here and wait for respond back its receipt that says that I got this. So UDP is just going to send and send incidents in the descent
06:23
so the layer four layer four is going to manage, manage how we do that. It's going to manage if we're sending TCP or UDP. If we need to wait for a receipt or if we need to just send and send in sentence and and send
06:38
all of this is negotiated. All of our if we're sending over TCP or UDP is negotiated based on the protocol that we're using based on later late levels, so we just want to keep in mind are big names here for later. For our TCP and UDP, it's going to be management and control
06:56
on splitting kind of communications and different packages.

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