WEBVTT 00:00.990 --> 00:05.160 The CPI is a combination of two protocols. 00:05.460 --> 00:13.050 These are the actual in my screen, just these are the transmission protocol, transmission control 00:13.050 --> 00:15.450 protocol plus internet protocol. 00:16.500 --> 00:17.070 So. 00:18.620 --> 00:23.680 These two particles form part of the Internet protocol suite IPS. 00:24.080 --> 00:31.220 So a conceptual model of how Nature Protocol sent network traffic over the internet that breaks down 00:31.220 --> 00:37.850 network communication into four layers, as shown in this illustration. 00:38.540 --> 00:43.820 So as you can see, Internet Protocol Application Layer transports their internet layer link layer, 00:43.820 --> 00:47.690 and these are the what these layers use, what protocols, says Laotians. 00:47.960 --> 00:50.540 And this is the link layer is the physical layer. 00:51.110 --> 00:57.470 So, uh, these are the two four layers from a protocol stack. 00:58.160 --> 01:03.410 So these links here's the all clear, uh, link layer. 01:03.800 --> 01:07.250 This is the layer one, layer two, layer three and layer form. 01:07.580 --> 01:09.770 This start with a link, clearly and one. 01:10.160 --> 01:12.500 So this layer is the lowest level. 01:12.500 --> 01:19.880 And this, uh, describes the physical mechanisms used, uh, to transfer information between nodes 01:20.060 --> 01:21.980 on a local network. 01:22.830 --> 01:23.570 Uh, Ben. 01:23.610 --> 01:27.340 One examples include, uh, internet here. 01:27.350 --> 01:28.270 Can I show you? 01:28.310 --> 01:31.100 So this is the Ethernet port, for example. 01:31.580 --> 01:36.260 Um, or point to point, uh, protocol. 01:36.780 --> 01:40.510 Uh, so these are the physical layer and top of them. 01:40.520 --> 01:43.490 This is the layer number two layer number two. 01:44.360 --> 01:46.570 Uh, so this is the internet layer. 01:46.580 --> 01:50.960 So this layer provides the mechanisms for addressing network notes. 01:51.320 --> 01:52.550 Well, I can layer one. 01:52.940 --> 01:56.390 The nodes don't have to be located on the local network. 01:56.600 --> 02:02.900 This level contains the, uh, IP for IPv6 on a model networks. 02:02.900 --> 02:08.450 The actual protocol used called either B I IP version four or IP version six. 02:08.900 --> 02:15.050 And and then let's talk about our, uh, third layer transport layer. 02:15.290 --> 02:15.590 Yeah. 02:16.610 --> 02:25.010 Transport layer these layers is responsible for connection between clients and servers, so sometimes 02:25.010 --> 02:31.910 ensuring the correct order of Pekar's and providing service multiplexing service multiplexing allows 02:31.910 --> 02:39.050 a single node to support multiple different services by assigning a different number for each service. 02:39.410 --> 02:43.090 So this number is called a part TCP. 02:43.220 --> 02:46.670 The user data protocol operate on this layer. 02:46.670 --> 02:51.830 TCP and UDP operate in this transport layer. 02:52.550 --> 03:00.730 And lastly, we have application layer here, so this layer contains network protocols such as Hypertext, 03:00.930 --> 03:08.210 the hypertext transfer protocol ATP, which transfers web page contents. 03:08.630 --> 03:16.850 Uh, we have the simple mail transport protocol for which transferring which transferring email and 03:16.850 --> 03:22.250 domain name system protocol, which converts a name to and not on the network. 03:22.800 --> 03:28.910 Further, this course we will focus primarily on this layer, actually, but we will focus on all of 03:28.910 --> 03:29.330 this there. 03:29.330 --> 03:31.220 So this is the most important layer for us. 03:31.970 --> 03:38.780 Each layer interacts only with the layer of two and below, but there is a must be external interaction 03:38.780 --> 03:39.620 within the stack. 03:40.190 --> 03:42.440 So like that. 03:48.310 --> 03:48.700 One. 03:49.270 --> 03:49.660 Yes. 04:08.150 --> 04:08.550 There. 04:13.900 --> 04:14.370 So. 04:19.690 --> 04:22.440 Now, let's pretend that new figure. 04:23.230 --> 04:25.060 Uh, for better understanding. 04:26.380 --> 04:26.800 Um. 04:27.890 --> 04:28.430 Yes. 04:29.270 --> 04:31.580 This is the one box here. 04:32.030 --> 04:33.960 And this is the mail. 04:34.700 --> 04:36.740 This will be our mail application. 04:41.640 --> 04:42.900 Mail application. 04:48.380 --> 04:49.220 Vacation. 04:52.930 --> 04:54.290 This is the mail application. 04:54.580 --> 05:00.160 And, um, this is the human years, so it's. 05:01.780 --> 05:04.270 Justin, users here, for example. 05:06.570 --> 05:09.420 This will be our user, so. 05:12.920 --> 05:16.370 It's it's some books here as well. 05:16.730 --> 05:28.010 So this will be a user interface interface, which is harsh HTML hash, HTML rendering, and we have 05:28.340 --> 05:30.740 we will conduct ourselves here. 05:32.030 --> 05:39.500 Content partners like, uh, tech such will jpg content. 05:41.230 --> 05:42.130 Serves. 05:43.300 --> 05:44.320 Passers. 05:45.670 --> 05:55.090 What this feeling is text, for example, hushed html jpg, the on the wheel, uh, top of below them 05:55.240 --> 05:56.350 is very real. 05:56.350 --> 05:59.710 Have network communication network home. 06:02.210 --> 06:11.150 So what these will is and SMTP is SMTP, for example, pop three or three and IMAP. 06:11.240 --> 06:12.770 So this is the email application. 06:13.640 --> 06:22.580 Uh, so SMTP, POP3 and IMAP is the mail protocols, and this will be network network. 06:23.600 --> 06:24.050 Here. 06:25.630 --> 06:27.880 And servers here, server. 06:29.950 --> 06:30.490 Sir. 06:32.560 --> 06:36.220 This network report is directly the server and user interface. 06:36.700 --> 06:38.890 Will direct that it'll go to our homeland. 06:39.430 --> 06:42.910 So typically, applications contains these components. 06:43.330 --> 06:47.140 First is network communication. 06:48.130 --> 06:56.000 So this component communicates over the network and processes incoming and outgoing outgoing data. 06:56.330 --> 06:57.450 What email application? 06:57.460 --> 07:04.960 The network communication is most likely in the standard protocol, such as a SMTP pump three and IMAP, 07:05.650 --> 07:08.200 and we have here content partners as well. 07:08.380 --> 07:09.850 So data is transferred over. 07:09.850 --> 07:15.350 A network usually contains content that must be extracted and processed. 07:15.910 --> 07:24.250 Content might be include textual data such as the body of an e-mail or it might be contain pictures 07:24.370 --> 07:25.240 or videos. 07:26.320 --> 07:28.930 And we have user interface for user. 07:29.500 --> 07:37.870 So the user interface allows the user to be received emails and to create new emails for transmission 07:38.080 --> 07:39.220 in a mail application. 07:39.220 --> 07:47.650 The user interface might display emails using hashed email or be in a web of a browser. 07:48.730 --> 07:52.810 Not that the user interacting with the user interface doesn't have to be human. 07:52.810 --> 08:00.400 Being caused by the application that automates the sending and receiving of emails triggered a command 08:00.400 --> 08:01.030 line tool. 08:02.090 --> 08:10.190 And we have here data encapsulation, which we will discuss this in the next lecture.