1 00:00:05,380 --> 00:00:07,860 I'll go through this in more detail later. 2 00:00:07,900 --> 00:00:13,580 Let's just look briefly at some of the devices that we had in the past and then some modern devices. 3 00:00:14,020 --> 00:00:19,930 The original Ethernet was 10 base five using this really big yellow cable. 4 00:00:19,990 --> 00:00:27,280 So this cable was restricted and distance the signal would attenuate from one end of the cable to the 5 00:00:27,280 --> 00:00:28,060 other. 6 00:00:28,120 --> 00:00:30,730 And what they developed were repeaters. 7 00:00:30,730 --> 00:00:34,100 This is an example of a very early repeater. 8 00:00:34,210 --> 00:00:38,590 This would repeat the signal from one port to another. 9 00:00:38,590 --> 00:00:42,110 We could use ten base five here or ten base two. 10 00:00:42,130 --> 00:00:49,180 So this amplified the signal basically didn't understand the actual signal but it just amplified the 11 00:00:49,180 --> 00:00:51,280 signal from one port to another. 12 00:00:51,280 --> 00:00:53,110 Now you'll notice it doesn't have many ports on it. 13 00:00:53,140 --> 00:00:54,660 We've only got two ports. 14 00:00:54,880 --> 00:00:58,270 So it was simply repeating from one port to another. 15 00:00:58,270 --> 00:01:00,120 So example of a repeater. 16 00:01:00,310 --> 00:01:04,210 They then developed what was called a multiple port repeater. 17 00:01:04,210 --> 00:01:07,570 This is a Cisco fast hub 400 series. 18 00:01:07,750 --> 00:01:11,320 So we've got RJ 45 connectors on the front. 19 00:01:11,500 --> 00:01:13,530 We've got power on the back. 20 00:01:13,600 --> 00:01:18,970 But the idea is a hub is essentially a multi port repeater. 21 00:01:18,970 --> 00:01:22,710 We've got multiple ports and we are simply repeating the signal. 22 00:01:23,140 --> 00:01:28,200 We would connect RJ 45 until the twisted pairs an example to these ports. 23 00:01:28,450 --> 00:01:34,840 And what a hub does is once again it simply repeats the signal without understanding what's going on. 24 00:01:34,840 --> 00:01:39,810 So it doesn't understand the frames that it receives or the information that it receives. 25 00:01:39,910 --> 00:01:42,240 It simply amplifies it. 26 00:01:42,340 --> 00:01:47,050 So a repeater here would amplify the signal amplified from one port to another. 27 00:01:47,050 --> 00:01:49,170 Here we've got a multiple repeater. 28 00:01:49,180 --> 00:01:52,830 It's repeating the signal from one port to multiple other ports. 29 00:01:52,900 --> 00:01:58,930 So if traffic was received on port one on this hub it would simply amplify the signal out of all of 30 00:01:58,930 --> 00:01:59,830 those ports. 31 00:01:59,920 --> 00:02:05,370 So it repeats the signal out of every other port without understanding any of the details. 32 00:02:05,380 --> 00:02:08,830 Here's an example of a net gear hub on the front. 33 00:02:08,830 --> 00:02:12,670 We have 24 RJ 45 ports and on the back. 34 00:02:12,670 --> 00:02:18,190 We've got 10 base two as well as 10 base five. 35 00:02:18,190 --> 00:02:24,580 So again this would allow me to connect different cable types on the back we could connect 10 base five 36 00:02:24,580 --> 00:02:25,460 as an example. 37 00:02:25,540 --> 00:02:31,140 And then on the front we could have UDP RG 45 cabling as we know today. 38 00:02:31,210 --> 00:02:33,160 This has no intelligence. 39 00:02:33,260 --> 00:02:35,120 There's no intelligence in the hub. 40 00:02:35,210 --> 00:02:37,140 There's no intelligence in the repeater. 41 00:02:37,150 --> 00:02:40,230 Remember this is just repeating the signal from one port to another. 42 00:02:40,270 --> 00:02:42,330 This is a multiple repeater. 43 00:02:42,580 --> 00:02:45,120 If something is received on this port it just amplifies it. 44 00:02:45,120 --> 00:02:48,810 Out of all the other ports or repeats it out of all the other ports. 45 00:02:49,030 --> 00:02:54,520 Otherwise we get attenuation of signals and the signals degrade over a period of time which restricts 46 00:02:54,520 --> 00:02:55,900 the length of a cable. 47 00:02:55,900 --> 00:02:59,680 This allows me to increase the length of the cable. 48 00:02:59,680 --> 00:03:05,110 Now the problem in those days is the more devices that you have on the network the more collisions that 49 00:03:05,110 --> 00:03:08,610 you're going to have which causes problems and slows the network down. 50 00:03:08,620 --> 00:03:09,910 I'll talk more about that later. 51 00:03:10,270 --> 00:03:12,340 But the idea is that this is a hub. 52 00:03:12,430 --> 00:03:13,930 This is a repeater. 53 00:03:13,930 --> 00:03:15,720 We don't worry too much about these days. 54 00:03:15,820 --> 00:03:21,810 A lot of people say David don't even show me hubs because they're pointless but they forget that wireless. 55 00:03:21,850 --> 00:03:27,250 This is an example of a wireless access point very modern wireless access point supports Wi-Fi sex the 56 00:03:27,250 --> 00:03:34,630 latest version of Wi-Fi at the time of this recording a Wi-Fi network or a wireless network is essentially 57 00:03:34,930 --> 00:03:37,040 a hub in the air. 58 00:03:37,120 --> 00:03:39,420 We are sharing the air. 59 00:03:39,580 --> 00:03:43,510 So whatever I'm saying can be heard by you if you're within range. 60 00:03:43,750 --> 00:03:48,300 Both of us can speak at the same time because it's a shared medium. 61 00:03:48,300 --> 00:03:54,880 We are sharing the air now Wi-Fi six does try and implement some very clever stuff to allow multiple 62 00:03:54,880 --> 00:03:56,840 devices to talk at the same time. 63 00:03:57,010 --> 00:04:01,680 So it kind of approaches a switch but it's still acting as a hub. 64 00:04:01,690 --> 00:04:02,630 So what is a switch. 65 00:04:02,840 --> 00:04:04,500 Here's an example of a switch. 66 00:04:04,510 --> 00:04:08,680 This is an older switch that is 750 very popular for doing labs. 67 00:04:08,680 --> 00:04:14,110 Cisco labs noticed lots of ports on the switch we got 48 ports on the switch. 68 00:04:14,110 --> 00:04:16,400 The number of ports on your switch varies. 69 00:04:16,420 --> 00:04:19,270 You can have very small switches you could have larger switches. 70 00:04:19,270 --> 00:04:24,860 Here's an example is a five Port switch T.P. linked switch very small switch. 71 00:04:24,920 --> 00:04:31,750 Has another four port switch from TB link so you don't necessarily have lots of ports but in an enterprise 72 00:04:31,750 --> 00:04:35,410 environment you typically will you'll have a lot of ports on a switch. 73 00:04:35,410 --> 00:04:37,090 These are smaller switches. 74 00:04:37,090 --> 00:04:42,250 The point is is that the form factor or the way that these devices look varies. 75 00:04:42,250 --> 00:04:49,510 But the big difference between a switch and a hub is a switch has intelligence a switch actually reads 76 00:04:49,540 --> 00:04:55,360 what are called the frames received on Ethernet when you send data into Ethernet we're sending what's 77 00:04:55,360 --> 00:04:56,710 called a frame. 78 00:04:56,710 --> 00:05:00,620 So this device uses what's called a MAC address table. 79 00:05:00,670 --> 00:05:02,740 It's the same as these devices of the top here. 80 00:05:02,860 --> 00:05:08,860 They basically receive frames and they have the intelligence to only forward the frames out of the correct 81 00:05:08,860 --> 00:05:09,310 ports. 82 00:05:09,840 --> 00:05:14,680 So if there was a device with a certain MAC address on this port and traffic was received on this port 83 00:05:14,800 --> 00:05:20,470 going to that MAC address it would only be sent out of that port rather than out of all ports a hub 84 00:05:21,010 --> 00:05:27,190 or multiple repeater is done when a when traffic is received on one port it just simply amplifies it 85 00:05:27,490 --> 00:05:33,180 or floods it is the term out of all ports so everyone receives that frame here. 86 00:05:33,220 --> 00:05:39,250 A switch has a MAC address table it has some intelligence and it learns where MAC addresses are in the 87 00:05:39,250 --> 00:05:43,680 network and then it will only forward the traffic out of the relevant ports. 88 00:05:43,810 --> 00:05:46,500 Based on the destination MAC address and a frame. 89 00:05:46,720 --> 00:05:51,070 So if traffic comes into this port it's going to you based on your mac address it's learned that you're 90 00:05:51,070 --> 00:05:55,720 connected to this port when traffic arrives in this port going to your mac address it's only going to 91 00:05:55,720 --> 00:06:01,500 be sent out of this port whereas if it arrived on a hub it would send it out of all ports. 92 00:06:01,570 --> 00:06:07,000 So a big difference between a switch and a hub is a switch has intelligence. 93 00:06:07,120 --> 00:06:09,400 It works at what's called Layer 2. 94 00:06:09,400 --> 00:06:11,550 We'll talk about that later in a moment. 95 00:06:11,590 --> 00:06:16,210 So it has some intelligence and it'll only forward the frames out of the correct ports. 96 00:06:16,210 --> 00:06:19,630 Now some people would say but hold on a minute David what is a bridge. 97 00:06:19,630 --> 00:06:20,320 A bridge. 98 00:06:20,350 --> 00:06:24,820 You can think of as an intermediate device between a switch and a hub. 99 00:06:24,820 --> 00:06:26,180 So we had repeaters first. 100 00:06:26,200 --> 00:06:32,020 Then we've got hubs and then we had bridges which basically did things in software they learned where 101 00:06:32,020 --> 00:06:39,070 the MAC addresses were of devices in the network and then someone rebranded their devices as switches 102 00:06:39,370 --> 00:06:42,160 because they could learn MAC addresses in hardware. 103 00:06:42,340 --> 00:06:46,910 So they use something called an application specific integrated circuit or a sec. 104 00:06:47,230 --> 00:06:52,710 So the lines are a little bit blurred but for the CCMA you don't have to worry about that a switch learns 105 00:06:53,110 --> 00:06:57,610 where devices are learns where their MAC addresses are and then we'll only forward the traffic out of 106 00:06:57,610 --> 00:07:02,690 the relevant ports a bridge was an intermediate device between a switch and a hub. 107 00:07:02,710 --> 00:07:09,010 So historically we had repeaters that we had hubs and we had bridges software switches if you like and 108 00:07:09,010 --> 00:07:11,380 then we have switches today. 109 00:07:11,380 --> 00:07:15,100 Now notice the number of ports on the switch there many many ports on the switch. 110 00:07:15,580 --> 00:07:21,660 So that's one of the features of switches they allow us to connect many devices in our local area network. 111 00:07:21,670 --> 00:07:27,680 They are essentially useful sending traffic within a local area network or LAN. 112 00:07:27,670 --> 00:07:31,600 We're not going to try and send it from one network to another. 113 00:07:31,600 --> 00:07:39,910 These operate on mac addresses using what's called Layer 2 in the OSA model or TCE IP model hubs or 114 00:07:39,910 --> 00:07:45,660 layer 1 devices they are basically dumb devices they don't understand what they receive. 115 00:07:45,760 --> 00:07:51,250 These are called Layer two devices because they use Ethernet frames and then we have routers which use 116 00:07:51,400 --> 00:07:54,370 IP addresses to rot from one network to another. 117 00:07:54,370 --> 00:07:56,500 They are called Layer three devices. 118 00:07:56,560 --> 00:08:01,900 We'll talk about those terms in a separate video layer one layer to layer three layer 4 and layer five 119 00:08:01,900 --> 00:08:08,080 to seven you need to know those layers you need to know the TTP IP and we say models so don't worry 120 00:08:08,080 --> 00:08:14,260 too much about that for the moment just get an understanding dumb device repeats everything that receives 121 00:08:14,260 --> 00:08:19,840 on one put out of all of the ports more intelligent device uses mac addresses learns where devices are 122 00:08:20,170 --> 00:08:21,560 and then we have writers. 123 00:08:21,850 --> 00:08:25,150 Now your home device might look something like this teepee link. 124 00:08:25,150 --> 00:08:27,460 This is a little tepee link right. 125 00:08:27,640 --> 00:08:31,970 It allows us to root from one network to another. 126 00:08:32,020 --> 00:08:38,950 Typically little routers like this allow us to go from our Ethernet LAN local area network onto the 127 00:08:39,070 --> 00:08:39,640 Internet. 128 00:08:39,700 --> 00:08:43,390 So to what's called a one wide area network. 129 00:08:43,390 --> 00:08:52,900 So Ethernet ports this is how we connect our devices to the broader wireless and then we've got a connection 130 00:08:52,900 --> 00:08:54,090 to the Internet. 131 00:08:54,090 --> 00:09:02,410 He has a Cisco router what you'll notice is the shroud it is as big as the switch but it has far fewer 132 00:09:02,410 --> 00:09:03,580 ports on it. 133 00:09:03,580 --> 00:09:07,660 We've only got a few Ethernet ports and then we've got other types of ports. 134 00:09:07,660 --> 00:09:09,960 These are what are called serial ports. 135 00:09:09,970 --> 00:09:14,950 Now fortunately in the new CCMA you don't have to learn about these serial interfaces. 136 00:09:14,950 --> 00:09:16,150 They were very slow. 137 00:09:16,150 --> 00:09:17,260 Older interfaces. 138 00:09:17,260 --> 00:09:23,650 The most common when technology and land technology tonight today is Ethernet so Ethernet is what you 139 00:09:23,650 --> 00:09:24,090 need to know. 140 00:09:24,670 --> 00:09:30,250 So that's why I'm spending so much time discussing Ethernet these older interfaces aren't that important 141 00:09:30,250 --> 00:09:31,330 today. 142 00:09:31,330 --> 00:09:32,770 But think of your home broader. 143 00:09:32,860 --> 00:09:34,520 How do you connect to the Internet. 144 00:09:34,540 --> 00:09:37,210 Maybe you've got an A DSL connection. 145 00:09:37,210 --> 00:09:42,120 So your service provider mine here in the U.K. is British Telecom. 146 00:09:42,190 --> 00:09:44,510 They've given me an A DSL connection. 147 00:09:44,530 --> 00:09:48,070 Now some of you may be fortunate enough to have fibre to your home. 148 00:09:48,160 --> 00:09:50,940 So in actual fact your one connection is Ethernet. 149 00:09:50,950 --> 00:09:56,020 In that case but in the old days it might have been something like the serial interface. 150 00:09:56,020 --> 00:09:58,840 But notice this right here this is an interesting road. 151 00:09:59,050 --> 00:10:00,410 Eighteen hundred series right. 152 00:10:00,730 --> 00:10:06,610 This is an older router that would be used in small medium business or in a remote branch office of 153 00:10:06,610 --> 00:10:08,560 a large corporate. 154 00:10:08,560 --> 00:10:11,160 This device does a lot of things. 155 00:10:11,200 --> 00:10:15,300 It has all telephone connections here where you could put old analog phones in. 156 00:10:15,520 --> 00:10:21,130 So these ports share these f access ports would allow you to connect an old analog phone to the rudder 157 00:10:21,580 --> 00:10:27,490 and then this would allow you to make telephone calls to your service provider like AT&T or British 158 00:10:27,490 --> 00:10:28,820 Telecom etc.. 159 00:10:28,990 --> 00:10:30,250 It's also got a way an interface. 160 00:10:30,250 --> 00:10:32,830 So one of these interfaces could go here. 161 00:10:32,890 --> 00:10:36,100 It also allows us to connect to the Internet. 162 00:10:36,130 --> 00:10:39,270 It's also got like a switch part to it. 163 00:10:39,280 --> 00:10:46,220 So the idea here is this is kind of like a hybrid device writers today mix a lot of switching with them. 164 00:10:46,420 --> 00:10:50,430 Like I said nothing is as simple as it seems in its purest form. 165 00:10:50,440 --> 00:10:53,860 A router will rot from one network to another. 166 00:10:53,860 --> 00:11:02,080 So as an example we are routing from Ethernet to serial or we are routing from physical Ethernet to 167 00:11:02,080 --> 00:11:05,950 wireless or we are writing from one connection type to another. 168 00:11:05,950 --> 00:11:09,970 So as an example this writer could support voice over IP. 169 00:11:09,970 --> 00:11:16,250 We could have IP phones talking to analog phones but this is where it gets a little bit less clear cut. 170 00:11:16,320 --> 00:11:22,030 This is what you need to remember a router has writing functionality in its most basic form. 171 00:11:22,060 --> 00:11:25,770 A writer writes from one IP network to another. 172 00:11:25,780 --> 00:11:31,240 So here we are talking about IP addresses such as IP version for IP version 6 addresses. 173 00:11:31,240 --> 00:11:37,780 We are routing from one network to another as in one IP network to another in a lot of cases. 174 00:11:37,780 --> 00:11:43,330 We would be routing from one physical media to a different physical media. 175 00:11:43,330 --> 00:11:48,640 This is typically used for connections to the Internet or to wide area networks. 176 00:11:48,640 --> 00:11:54,430 So we are connecting from a local area network to a wide area network switches are typically used in 177 00:11:54,430 --> 00:12:00,240 the local area networks are local within the building as an example local at your home you're not going 178 00:12:00,240 --> 00:12:03,830 to use this to write to the Internet or write to other sites. 179 00:12:04,240 --> 00:12:09,130 A router does that function so it rots from one network to another layer to switch as this is called 180 00:12:09,130 --> 00:12:15,730 uses Mac addresses but switches today have routing functionality so switch like this is called a layer 181 00:12:15,730 --> 00:12:22,690 3 switch because it has routing capabilities built into it and then it'll rot from one VLAN or virtual 182 00:12:22,690 --> 00:12:26,300 local area network to another virtual local area network. 183 00:12:26,470 --> 00:12:31,340 Basically from one subnet to another subnet we'll talk about that later. 184 00:12:31,360 --> 00:12:39,670 Thing to remember is basic definition routing switching dumb device so no intelligence here. 185 00:12:39,670 --> 00:12:43,510 Intelligence based on Mac addresses intelligence based on IP addresses.