WEBVTT 00:00.830 --> 00:02.030 Data transmission. 00:03.220 --> 00:09.160 Let's briefly look at how data is transferred from one node to another using the IPS data encapsulation 00:09.160 --> 00:09.730 model. 00:09.760 --> 00:14.230 In this diagram, you are seeing the simple Ethernet network with the three nodes. 00:14.230 --> 00:16.270 One, two, two, three. 00:16.870 --> 00:24.160 So here in this example, the node at here, actually let's name this the typhoons. 00:25.460 --> 00:26.190 Computer. 00:27.430 --> 00:33.340 And here let's actually make this oxly.com and. 00:34.230 --> 00:36.060 Or for example. 00:36.960 --> 00:38.010 iPhones. 00:39.840 --> 00:41.040 Network, right? 00:41.280 --> 00:42.540 Yeah, in our laptop. 00:44.890 --> 00:45.140 Here. 00:45.970 --> 00:46.660 So. 00:47.760 --> 00:56.980 And for example, with the IP address, 192.168 .0. 101 named Typhoons. 00:56.980 --> 01:06.910 Computer Typhoons computer wants to send the data using the IP protocol to the node at the with the 01:06.940 --> 01:08.020 IP address here. 01:08.320 --> 01:09.340 Telecom. 01:09.370 --> 01:15.130 The IP address 192.168 .0. 108. 01:16.640 --> 01:18.460 And the switch device. 01:18.470 --> 01:20.300 This is the switch device of us. 01:21.440 --> 01:26.750 Forwards Ethernet frames between all nodes on the network. 01:27.230 --> 01:33.080 The switch doesn't need an IP address because it operates only at the link layer. 01:33.350 --> 01:35.860 Remember what the what link layer is this? 01:35.870 --> 01:37.430 This is the layer one. 01:39.860 --> 01:42.620 So the switch device. 01:43.550 --> 01:49.620 Doesn't need an IP address because it operates only at the link layer. 01:49.640 --> 01:53.360 And here I will write that down. 01:53.360 --> 02:00.500 What what is take place takes place to send the data between two nodes. 02:00.530 --> 02:01.700 The first step. 02:02.360 --> 02:04.460 The operating. 02:05.620 --> 02:06.220 System. 02:06.220 --> 02:07.810 Actually, let me copy this. 02:07.810 --> 02:08.250 Here. 02:08.260 --> 02:08.770 Yeah. 02:10.690 --> 02:11.920 And make topper. 02:11.950 --> 02:13.000 The first step. 02:13.000 --> 02:13.840 Step one. 02:14.560 --> 02:15.460 Step one. 02:16.260 --> 02:20.970 The operating system network stack. 02:21.760 --> 02:25.390 So the operating system network stack node. 02:27.280 --> 02:35.140 Encapsulates the application and transport layer data and builds an IP packet with a source address 02:35.140 --> 02:41.890 of 192.168 .0. 101. 02:42.640 --> 02:45.580 Remember, this is the Typhoon's computer IP address. 02:46.640 --> 03:00.110 And the destination address here I read wrote that as a to the destination address of 192.168 .0. 108. 03:01.040 --> 03:03.380 And the step two after that. 03:03.380 --> 03:06.380 Step two is, um. 03:07.090 --> 03:15.700 The operating system can at this point encapsulate the IP data as an Ethernet frame. 03:17.790 --> 03:25.650 Encapsulate IP IP data as an Ethernet frame. 03:30.560 --> 03:34.310 So the operating system can at this point, as I said. 03:35.210 --> 03:42.740 Encapsulate IP data as an Ethernet frame, but it might not know the Mac address of the target node 03:42.740 --> 03:49.910 and it can request the Mac address for a particular IP address using the address resolution protocol. 03:49.940 --> 03:58.820 ARP, which sends a request to all nodes on the network to find that the Mac address for the destination 03:58.850 --> 04:01.850 IP address and a step three. 04:01.910 --> 04:11.210 Step three is once the node at Typhoon's computer receives an address resolution protocol response, 04:11.210 --> 04:13.970 it can build the frame right as here. 04:14.910 --> 04:19.980 So the setting source address of the local MAC address of here. 04:20.010 --> 04:24.300 1155774A1B, b. 04:24.480 --> 04:26.310 And the destination address. 04:26.310 --> 04:30.630 So the destination address is actually this and here. 04:31.960 --> 04:41.260 Our address resolution Protocol just figured out our typhoon's computer Mac address and tells us that 04:41.260 --> 04:44.740 our source MAC address is Typhoon's computer Mac address. 04:44.740 --> 04:46.930 And the destination is this. 04:49.080 --> 04:51.450 And the step four is. 04:55.830 --> 04:59.370 Actually a sharp response. 04:59.790 --> 05:08.580 Step three was area response and the step four is that then the lastly, the switch forwards the frame 05:08.580 --> 05:18.790 to the destination node, which unpacks the IP packet and verifies that the destination IP address matches. 05:18.810 --> 05:28.560 Then the IP payload is extracted and the passes up to the stack to be received by the waiting application.