1 00:00:02,220 --> 00:00:14,220 Today we are going to talk about something that is very important in our society 2 00:00:14,220 --> 00:00:26,219 because it has changed our life, because it improved the collaborative work and it led us to share our contents. 3 00:00:26,219 --> 00:00:40,700 So, it's a real revolution in the way we usually work using this kind of tools, IT tools. 4 00:00:40,700 --> 00:00:48,020 We are going to talk about network, computer network and obviously the internet. 5 00:00:48,020 --> 00:01:32,549 So the first thing that we must know is the definition of a computer network. 6 00:01:32,549 --> 00:01:40,709 A computer network is a set of computers and devices connected to each other for the purpose 7 00:01:40,709 --> 00:01:44,950 of sharing information and resources. 8 00:01:44,950 --> 00:01:55,510 that can be shared on the network not just only a software or files but it can also some hardware, 9 00:01:56,709 --> 00:02:07,329 hard disks, printers and so on. It can be shared the program information and data managed by 10 00:02:07,329 --> 00:02:14,680 different users also. In all networks or communication system you will find 11 00:02:14,680 --> 00:02:23,979 the same elements, the elements of communication that are transmitter, receiver, we also need a 12 00:02:23,979 --> 00:02:36,400 channel and obviously the measured that I want to transmit that must be encoded and decoded. 13 00:02:36,400 --> 00:02:47,400 So the code is so important. To do the communication with the computers we have already known some codes. 14 00:02:47,400 --> 00:03:06,240 If we take into consideration the size of the computer network, we can classify the networks into at least three different types. 15 00:03:06,240 --> 00:03:19,620 The lowest or the smallest is land. In a land or a local area network you just only cover a building, 16 00:03:19,620 --> 00:03:32,580 no more than a building. If you cover more or less a city you have a man network, 17 00:03:32,580 --> 00:03:42,539 the metropolitan area network and if it is bigger you have a one which is a large 18 00:03:42,539 --> 00:03:50,460 scale network a wide area networks so taking into consideration the size of 19 00:03:50,460 --> 00:04:03,870 the computer network we have these three types if you take if you take into 20 00:04:03,870 --> 00:04:12,750 consideration the ownership we can have public private and virtual private networks private 21 00:04:12,750 --> 00:04:25,889 networks is a you you you have a sex in a public way it's a global way one best example can be the 22 00:04:25,889 --> 00:04:34,470 internet it is private is just only for some users for example the different 23 00:04:34,470 --> 00:04:41,930 types of intranets you have a lot of types of intranets most commonly LANs 24 00:04:41,930 --> 00:04:50,370 generally is for LANs or for FTP services also and finally virtual private 25 00:04:50,370 --> 00:04:58,310 network is the interconnection of various providers network using the 26 00:04:58,310 --> 00:05:16,769 structure of global network well if you take into consideration how to manage 27 00:05:16,769 --> 00:05:27,689 the network we can have two types client server that is an old-fashioned model in 28 00:05:27,689 --> 00:05:30,810 in which you need at least one computer 29 00:05:30,810 --> 00:05:35,050 which is different from the other computers, the client. 30 00:05:35,050 --> 00:05:38,670 This computer control and manage the traffic 31 00:05:38,670 --> 00:05:43,670 of the network, and it's usually so called a server. 32 00:05:45,209 --> 00:05:49,949 So you need a server in order to manage the network. 33 00:05:51,449 --> 00:05:56,449 And the rest of the computers must connect it to it. 34 00:05:57,689 --> 00:06:24,490 But nowadays it's very very usual that we haven't any server, all the computers are servers, so we usually have peer-to-peer network in which there is no nodes, all nodes or workstations are simultaneously clients and servers, and it's a new model that is usually used nowadays. 35 00:06:24,490 --> 00:06:40,060 If you take into consideration the topology, we have three main types. 36 00:06:40,060 --> 00:06:43,600 The first one is bus. 37 00:06:43,600 --> 00:06:53,769 The networks share the same channel, called a bus, with a single cable, is no longer used. 38 00:06:53,769 --> 00:07:03,569 In topology, the information circulates in one direction and each computer analyzes whether 39 00:07:03,569 --> 00:07:07,009 it is the target for the information. 40 00:07:07,009 --> 00:07:19,550 In star topology, all computers are connected to a hub or a switch which transmits the information. 41 00:07:19,550 --> 00:07:33,259 The most common thing is that we have mixed topologies nowadays. 42 00:07:33,259 --> 00:07:40,300 Well, other important thing is if we have cable or not, or we have wireless, that's 43 00:07:40,300 --> 00:07:45,579 the reason why we can use different types of wire. 44 00:07:45,579 --> 00:07:52,740 The most common is UDP, unsheathed wisdom pair, it's a cable consisting of copper or 45 00:07:52,740 --> 00:07:59,620 aluminum wires interlaced in pairs to avoid interference. 46 00:07:59,620 --> 00:08:07,579 Depending on the number of wires we use and the length of each strand, we have different 47 00:08:07,579 --> 00:08:16,990 speeds of transmission, and it's called category cuts. 48 00:08:16,990 --> 00:08:24,529 So we have different cables with different capacity. 49 00:08:24,529 --> 00:08:37,769 Another type of cable can be STP that is similar to UTP but is more secure. 50 00:08:37,769 --> 00:08:48,309 Nowadays you usually use also optical fiber that consists of a group of very thin wires 51 00:08:48,309 --> 00:08:55,509 made of transparent material, generally glass or plastic, over with pulses or light 52 00:08:55,509 --> 00:09:03,830 repressing transmitting data and sent. The light source be laser or LED. It has very high 53 00:09:05,590 --> 00:09:12,309 brand width and its speed is bigger. For Wi-Fi technology, 54 00:09:12,309 --> 00:09:26,590 which is a computer network data we need a Wi-Fi routers 0.6 as a remote transmitters so we can 55 00:09:26,590 --> 00:09:38,110 use recession devices Wi-Fi cars and so on motherboards is a very is is the the technology 56 00:09:38,110 --> 00:09:55,379 that we usually use nowadays without any cable wireless if we want to create the LAN as over 57 00:09:56,980 --> 00:10:04,980 other apps with the computer you need some hardware and also some software the typical 58 00:10:04,980 --> 00:10:13,220 hardware is in this slide we have the network card or the network board a network card are 59 00:10:13,220 --> 00:10:21,299 devices that connect computers to the network and are usually integrated into the motherboards or 60 00:10:21,299 --> 00:10:30,019 mobile computers a other thing is the router this is a computer network interconnection device 61 00:10:30,659 --> 00:10:39,139 its main function is to send information and find the best route that connect to computers 62 00:10:39,139 --> 00:10:51,139 We also can have switches, hub, but it's not so much usual, these both are the most usual. 63 00:10:51,139 --> 00:10:56,139 Well, apart from the hardware, we also need some. 64 00:10:56,139 --> 00:11:10,009 The network protocol is the software required for two computers in a network to communicate with each other. 65 00:11:10,009 --> 00:11:21,690 Computers speak the same language to share information, and this language is usually 66 00:11:21,690 --> 00:11:26,460 so-called communication protocol. 67 00:11:26,460 --> 00:11:35,240 Although there are a lot of protocols, nowadays we usually use the TCPIP protocol. 68 00:11:35,240 --> 00:11:43,000 The TCP IP protocol controls the packets of different datagrams. 69 00:11:43,000 --> 00:11:47,299 The IP is responsible for addressing and the ports. 70 00:11:47,299 --> 00:11:55,019 Each node or element in a network must be identified by its IP address. 71 00:11:55,019 --> 00:12:03,600 The IP number consists in a set of four decimal figures of one byte separation by dots, which 72 00:12:03,600 --> 00:12:16,200 can have values from 0 to 255 and the IP address gives you information about the 73 00:12:16,200 --> 00:12:23,559 type of net and the type of the connection for example if you are in the 74 00:12:23,559 --> 00:12:31,500 same land all the figures in the IP address are the same if set the tool 75 00:12:31,500 --> 00:12:40,159 this to the last two the last two is your own your own others is what 76 00:12:40,159 --> 00:12:51,769 identified you in a land source for example apart from this it's important 77 00:12:51,769 --> 00:13:03,289 to know how to routine or the content of a gateway we usually do our networks in 78 00:13:03,289 --> 00:13:15,409 With the land networks, we create the manned networks and with the manned werewolves, we 79 00:13:15,409 --> 00:13:18,610 create one werewolf in this way. 80 00:13:18,610 --> 00:13:27,909 So to control the access to the nest level, we need what we usually call a gateway, mostly 81 00:13:27,909 --> 00:13:31,350 in the land level. 82 00:13:31,350 --> 00:13:39,009 The gateway is the IP address of the access to the internet in a LAN. 83 00:13:39,009 --> 00:13:51,220 So all the computers must connect it to this gateway if they want to connect to the internet. 84 00:13:51,220 --> 00:14:04,389 Finally, some services that are really interesting, for example, it is really complicated to memorize 85 00:14:04,389 --> 00:14:12,629 set of figure the IP address but you can transfer this IP address in something 86 00:14:12,629 --> 00:14:19,450 that uses and you understand better is what we usually so 87 00:14:19,450 --> 00:14:42,450 called DNS. So in DNS, for example, instead of 147.96.1.15, we can use www.ucmx. You know 88 00:14:42,450 --> 00:14:51,690 www means that you are on the internet worldwide web then is the mine and you 89 00:14:51,690 --> 00:14:57,389 can also have a subdomain and finally is connected with the country or the 90 00:14:57,389 --> 00:15:14,100 activity of the web pages well in any case in any case the combination of one 91 00:15:14,100 --> 00:15:24,080 P address and the port that let you to do the connection this combination is 92 00:15:24,080 --> 00:15:33,620 usually so called socket so in this table you can know the ports that do the 93 00:15:33,620 --> 00:15:40,100 connection and the protocol and the purpose of service that you can have if 94 00:15:40,100 --> 00:15:45,940 you use this combination for example you have this this protocol is very 95 00:15:47,779 --> 00:15:51,299 it's very familiar for you because it's the control is the protocol 96 00:15:52,259 --> 00:16:00,980 for website weights and this is for file transfer or all of these protocols are for incoming email 97 00:16:00,980 --> 00:16:15,139 so the socket is a the combination of the protocol and the port I think is all that 98 00:16:15,139 --> 00:16:28,519 you need to know connected with networks then maybe we I think I'm going to to do 99 00:16:28,519 --> 00:16:35,980 exercises and finally a test.