1 00:00:00,660 --> 00:00:10,200 The PDU, The protocol data unit in each layer contains the payload data that is being transmitted, 2 00:00:10,200 --> 00:00:17,040 and it's a common to prefix a header which contains information required for the payload data to be 3 00:00:17,040 --> 00:00:23,250 transmitted, such as the addresses of the source and destination nodes on the network to the payload 4 00:00:23,250 --> 00:00:23,710 data. 5 00:00:23,730 --> 00:00:33,480 So sometimes the protocol data unit PDU also has a footer here that is suffixed to the payload data 6 00:00:33,480 --> 00:00:39,900 and contains values needed to ensure correct transmission, such as error checking information. 7 00:00:39,900 --> 00:00:48,960 And here in this diagram I created how pdus are laid out in the eips. 8 00:00:48,990 --> 00:00:55,260 Remember from the previous lectures IPS means Internet protocol suite. 9 00:00:58,880 --> 00:01:01,880 So let's get started with the application layer here. 10 00:01:01,880 --> 00:01:09,380 So you can see here we have layer four, we have application session, um, internet layer and the link 11 00:01:09,380 --> 00:01:09,920 layer. 12 00:01:09,950 --> 00:01:15,830 Now I will explain all of these layers and their payloads heaters one by one. 13 00:01:15,830 --> 00:01:23,720 So the TCP header contains a source and destination port number which is here. 14 00:01:25,280 --> 00:01:28,910 Source and destination port number here. 15 00:01:29,630 --> 00:01:36,860 And these port numbers allow a single node to have a multiple unique network. 16 00:01:36,860 --> 00:01:49,580 Connections and port numbers for TCP and UDP ranges from 0 to 65,500. 17 00:01:51,060 --> 00:01:51,870 35. 18 00:01:57,010 --> 00:02:01,780 And the most port numbers are assigned as needed to new connections. 19 00:02:01,780 --> 00:02:08,350 But some numbers have been given a special assignment such as the Port 80 for HTTP. 20 00:02:08,380 --> 00:02:14,650 You can find the current list of assigned port numbers in the ATC services file on the most Unix like 21 00:02:14,650 --> 00:02:23,380 operating system, but you can also check in from the Wikipedia from internet and TCP payload and header 22 00:02:23,380 --> 00:02:32,290 are commonly called the segment where the UDP payload and header are commonly called a datagram. 23 00:02:33,370 --> 00:02:38,260 The IPA protocol uses a source and destination headers. 24 00:02:41,420 --> 00:02:51,290 The destination address lost the data to be sent to a specific node on the network and the source address. 25 00:02:51,320 --> 00:03:01,100 Lost the receiver of the data to know which node sent the data and lost the receiver to reply to the 26 00:03:01,100 --> 00:03:01,820 sender. 27 00:03:07,240 --> 00:03:15,910 IPv4 uses 32 bit addresses, which you will typically see written as a four numbers separated by dots 28 00:03:15,910 --> 00:03:17,500 such as this. 29 00:03:18,580 --> 00:03:20,950 192168. 30 00:03:25,040 --> 00:03:27,230 192168. 31 00:03:27,260 --> 00:03:28,040 Here. 32 00:03:29,420 --> 00:03:30,620 Ten and one. 33 00:03:30,620 --> 00:03:32,300 So this is an example. 34 00:03:32,330 --> 00:03:43,010 IP version four, IP address and IPv6 actually let me notify their IP version four. 35 00:03:44,430 --> 00:03:44,700 So. 36 00:03:45,090 --> 00:03:48,120 But the IPV six here. 37 00:03:50,180 --> 00:03:56,690 IPv6 uses 128 bit addresses. 38 00:03:58,850 --> 00:04:07,100 Because 32 bit addresses aren't sufficient for the numbers of nodes on the modern networks. 39 00:04:07,930 --> 00:04:14,810 IPv6 addresses are usually written as a hexadecimal number separated by colons such as. 40 00:04:14,830 --> 00:04:25,330 For example, if a 80 0004 times zero here, actually let me increase the size it here. 41 00:04:26,250 --> 00:04:27,240 000. 42 00:04:27,510 --> 00:04:28,740 And. 43 00:04:30,280 --> 00:04:32,620 So this is an example. 44 00:04:32,650 --> 00:04:35,800 IPV four IPV six address. 45 00:04:36,690 --> 00:04:39,510 Long strings of four times zero. 46 00:04:39,510 --> 00:04:41,910 As you can see here, we've written like that. 47 00:04:42,270 --> 00:04:48,960 Long strings of 000 numbers are collapsed into two columns. 48 00:04:48,960 --> 00:04:57,060 For example, if you want to read, write this IPV IP version six number easily. 49 00:04:57,060 --> 00:04:58,530 You can also write like that. 50 00:04:58,530 --> 00:04:59,190 For example. 51 00:04:59,190 --> 00:05:00,690 One, two, three. 52 00:05:00,780 --> 00:05:02,370 So one. 53 00:05:05,190 --> 00:05:05,820 Two, three. 54 00:05:13,860 --> 00:05:18,050 The Internet also contains source and destination address. 55 00:05:19,430 --> 00:05:22,090 Source and destination address. 56 00:05:22,950 --> 00:05:32,310 Ethernet uses a 64 bit value called a media access control address, which is typically set during a 57 00:05:32,310 --> 00:05:35,400 manufacture of the Ethernet adapter. 58 00:05:35,400 --> 00:05:44,370 And you will usually see MAC addresses written as a series of hexadecimal numbers separated by dashes 59 00:05:44,370 --> 00:05:45,810 or colons. 60 00:05:46,170 --> 00:05:49,980 For example, Mac Address three writes like this. 61 00:05:50,100 --> 00:05:51,270 Example zero. 62 00:05:51,870 --> 00:05:52,440 A. 63 00:05:53,440 --> 00:05:54,220 With dashes. 64 00:05:54,220 --> 00:05:55,430 We will separate here. 65 00:05:55,600 --> 00:05:58,330 28 and nine. 66 00:05:59,590 --> 00:06:02,080 For a five. 67 00:06:03,040 --> 00:06:12,370 So this is an example media access control address and the Ethernet payload, including the header and 68 00:06:12,370 --> 00:06:17,230 footer is commonly referred as frame.