1 1 00:00:00,490 --> 00:00:02,220 Fiber media. 2 2 00:00:02,220 --> 00:00:04,140 The next type of cable we need to talk about 3 3 00:00:04,140 --> 00:00:05,830 is fiber optic cables. 4 4 00:00:05,830 --> 00:00:07,930 Now fiber optic cables are going to use light 5 5 00:00:07,930 --> 00:00:10,070 from an LED, a light emitting diode, 6 6 00:00:10,070 --> 00:00:12,350 or a laser to transmit information 7 7 00:00:12,350 --> 00:00:14,450 through a thin piece of glass fiber. 8 8 00:00:14,450 --> 00:00:16,800 Now fiber optic cables are great because they're immune 9 9 00:00:16,800 --> 00:00:19,210 to electromagnetic interference, or EMI, 10 10 00:00:19,210 --> 00:00:20,750 because there's no electricity involved 11 11 00:00:20,750 --> 00:00:23,670 in the data transmission as it's going down that cable. 12 12 00:00:23,670 --> 00:00:26,310 Also because we're using light instead of electricity, 13 13 00:00:26,310 --> 00:00:28,710 our signal can go an extremely long distance 14 14 00:00:28,710 --> 00:00:31,270 without much attenuation or signal loss. 15 15 00:00:31,270 --> 00:00:32,480 Whereas our copper cables, 16 16 00:00:32,480 --> 00:00:34,420 specifically cat 3 through cat 7, 17 17 00:00:34,420 --> 00:00:36,330 could only go about 100 meters, 18 18 00:00:36,330 --> 00:00:38,370 fiber optic cables can go hundreds of meters, 19 19 00:00:38,370 --> 00:00:40,050 or even hundreds of miles. 20 20 00:00:40,050 --> 00:00:42,730 After all, we have some really long fiber optic cables 21 21 00:00:42,730 --> 00:00:44,070 that are sitting on the ocean floor 22 22 00:00:44,070 --> 00:00:45,500 between the United States and Europe, 23 23 00:00:45,500 --> 00:00:48,720 and that is a huge distance all the way across the Atlantic. 24 24 00:00:48,720 --> 00:00:50,410 Now, this is one of the biggest benefits 25 25 00:00:50,410 --> 00:00:51,690 of fiber optic cables. 26 26 00:00:51,690 --> 00:00:55,130 It can cover an expansive range and longer distances. 27 27 00:00:55,130 --> 00:00:56,210 In addition to that, 28 28 00:00:56,210 --> 00:00:58,630 we can turn the light on and off very quickly 29 29 00:00:58,630 --> 00:01:01,810 adding to higher beam with applications by using fiber. 30 30 00:01:01,810 --> 00:01:04,100 If you remember from our copper media discussions, 31 31 00:01:04,100 --> 00:01:06,420 we were talking in terms of 10 megabits per second, 32 32 00:01:06,420 --> 00:01:09,220 100 megabits per second, one gigabit per second, 33 33 00:01:09,220 --> 00:01:11,610 10 gigabits per second, and things like that. 34 34 00:01:11,610 --> 00:01:13,100 But now that we've moved on to fiber, 35 35 00:01:13,100 --> 00:01:14,240 we can start talking about things 36 36 00:01:14,240 --> 00:01:16,220 in the terabits per second range. 37 37 00:01:16,220 --> 00:01:18,380 In fact, all the way back in 2012, 38 38 00:01:18,380 --> 00:01:21,030 the Japanese telecommunications company NTT 39 39 00:01:21,030 --> 00:01:24,260 was able to send data at one petabit per second. 40 40 00:01:24,260 --> 00:01:26,440 Now that is really, really fast. 41 41 00:01:26,440 --> 00:01:28,300 And so fiber is starting to be used 42 42 00:01:28,300 --> 00:01:30,360 in a lot of extremely fast networks. 43 43 00:01:30,360 --> 00:01:32,030 And it's usually not the fiber cable 44 44 00:01:32,030 --> 00:01:34,280 that becomes your limitation in the network anymore, 45 45 00:01:34,280 --> 00:01:36,560 instead, it's your other networking equipment, 46 46 00:01:36,560 --> 00:01:37,520 things like your switches, 47 47 00:01:37,520 --> 00:01:39,490 and your routers, and your end user devices, 48 48 00:01:39,490 --> 00:01:40,770 they just can't keep up. 49 49 00:01:40,770 --> 00:01:42,160 And so for this reason, 50 50 00:01:42,160 --> 00:01:43,710 most business class networks 51 51 00:01:43,710 --> 00:01:46,790 are still going to use fiber around 10 gigabits per second, 52 52 00:01:46,790 --> 00:01:48,620 because of those switches and routers. 53 53 00:01:48,620 --> 00:01:50,870 But this is more of a cost benefit decision 54 54 00:01:50,870 --> 00:01:54,120 than a technical limitation of the fiber cables themselves. 55 55 00:01:54,120 --> 00:01:57,590 So if fiber is so great with a huge expensive range, 56 56 00:01:57,590 --> 00:01:59,040 and super high speeds, 57 57 00:01:59,040 --> 00:02:00,570 there's got to be some drawbacks, right? 58 58 00:02:00,570 --> 00:02:02,430 Why isn't everyone using fiber? 59 59 00:02:02,430 --> 00:02:05,610 Well, we really do have two main drawbacks with fiber. 60 60 00:02:05,610 --> 00:02:07,700 First, fiber is expensive. 61 61 00:02:07,700 --> 00:02:09,690 Now, the price of fiber continues to drop, 62 62 00:02:09,690 --> 00:02:11,030 and it has year over year, 63 63 00:02:11,030 --> 00:02:13,730 but it's still much more expensive than a copper network. 64 64 00:02:13,730 --> 00:02:16,410 For this reason, most businesses only use fiber 65 65 00:02:16,410 --> 00:02:18,030 to connect backbones of their networks 66 66 00:02:18,030 --> 00:02:19,160 to their edge switches, 67 67 00:02:19,160 --> 00:02:20,580 or they're going to use fiber 68 68 00:02:20,580 --> 00:02:22,150 if they need to cover a large distance 69 69 00:02:22,150 --> 00:02:23,890 that they can't cover with copper. 70 70 00:02:23,890 --> 00:02:26,910 Second, fiber is more difficult to work with than copper. 71 71 00:02:26,910 --> 00:02:29,400 In fact, when I teach network plus in the classroom, 72 72 00:02:29,400 --> 00:02:32,310 I teach my students how to build their own Cat 5e cables. 73 73 00:02:32,310 --> 00:02:35,540 Now for less than $10, I can give each student a crimper, 74 74 00:02:35,540 --> 00:02:37,520 a set of connectors, and a cable tester, 75 75 00:02:37,520 --> 00:02:38,820 and they can take it home with them, 76 76 00:02:38,820 --> 00:02:40,490 and they can do it in about 10 minutes 77 77 00:02:40,490 --> 00:02:42,110 to learn how to build their own cables. 78 78 00:02:42,110 --> 00:02:43,450 It's really easy. 79 79 00:02:43,450 --> 00:02:44,670 Now, fiber on the other hand 80 80 00:02:44,670 --> 00:02:46,280 is much more difficult to work with, 81 81 00:02:46,280 --> 00:02:48,490 and it requires special tools and training 82 82 00:02:48,490 --> 00:02:50,370 to learn how to make those fiber cables, 83 83 00:02:50,370 --> 00:02:52,610 or to repair broken fiber cables. 84 84 00:02:52,610 --> 00:02:53,600 In my experience, 85 85 00:02:53,600 --> 00:02:56,580 it costs about five to 10 times more to run a fiber cable 86 86 00:02:56,580 --> 00:02:58,270 than it does to run a copper cable 87 87 00:02:58,270 --> 00:03:01,220 inside an office building, or between office buildings. 88 88 00:03:01,220 --> 00:03:03,010 Now, even with the drawbacks, and expense, 89 89 00:03:03,010 --> 00:03:05,200 and difficulty of working with fiber optic cables, 90 90 00:03:05,200 --> 00:03:07,100 fiber optics definitely have a place 91 91 00:03:07,100 --> 00:03:08,690 in most enterprise networks. 92 92 00:03:08,690 --> 00:03:09,870 And so we need to spend some time 93 93 00:03:09,870 --> 00:03:11,870 going over the different types of fiber optic cables 94 94 00:03:11,870 --> 00:03:13,510 that you may come across. 95 95 00:03:13,510 --> 00:03:16,120 First, we need to categorize our fiber optic cables, 96 96 00:03:16,120 --> 00:03:18,260 and we do this as either single-mode fibers, 97 97 00:03:18,260 --> 00:03:19,840 or multi-mode fibers. 98 98 00:03:19,840 --> 00:03:22,010 Now single mode fibers, or SMF, 99 99 00:03:22,010 --> 00:03:23,640 is a type of fiber optic cable 100 100 00:03:23,640 --> 00:03:25,530 that carries a single beam of light directly 101 101 00:03:25,530 --> 00:03:28,260 from one end of the cable to the other end of the cable. 102 102 00:03:28,260 --> 00:03:29,140 To achieve this, 103 103 00:03:29,140 --> 00:03:31,670 a single mode fiber has a smaller and thinner core 104 104 00:03:31,670 --> 00:03:33,420 than does a multimode fiber. 105 105 00:03:33,420 --> 00:03:34,550 Now, single mode fiber 106 106 00:03:34,550 --> 00:03:36,310 is used for long distance communications 107 107 00:03:36,310 --> 00:03:37,660 due to its smaller core size 108 108 00:03:37,660 --> 00:03:40,320 of 8.3 to 10 microns in diameter. 109 109 00:03:40,320 --> 00:03:41,980 This smaller core size allows 110 110 00:03:41,980 --> 00:03:43,750 for a more precise signal transmission 111 111 00:03:43,750 --> 00:03:45,140 over a longer distance 112 112 00:03:45,140 --> 00:03:47,850 because it forces the light to travel along a single path 113 113 00:03:47,850 --> 00:03:49,170 down the center of that cable 114 114 00:03:49,170 --> 00:03:51,030 without being dispersed around. 115 115 00:03:51,030 --> 00:03:52,900 Now, if you see workers with a large roll 116 116 00:03:52,900 --> 00:03:54,730 of fiber optic cable in your neighborhood, 117 117 00:03:54,730 --> 00:03:57,160 this is usually going to be a single mode fiber, 118 118 00:03:57,160 --> 00:03:59,090 and they're going to be able to cover a long distance 119 119 00:03:59,090 --> 00:04:00,990 from their internet service providers facility 120 120 00:04:00,990 --> 00:04:02,290 all the way into your neighborhood, 121 121 00:04:02,290 --> 00:04:03,840 and that's why they do it. 122 122 00:04:03,840 --> 00:04:05,230 The second type of fiber we have 123 123 00:04:05,230 --> 00:04:08,030 is known as multimode fiber, or MMF. 124 124 00:04:08,030 --> 00:04:10,810 Now multimode fiber is a type of fiber optic cable 125 125 00:04:10,810 --> 00:04:11,920 that carries a beam of light 126 126 00:04:11,920 --> 00:04:13,500 as it's data transmission medium, 127 127 00:04:13,500 --> 00:04:15,190 just like a single mode fiber, 128 128 00:04:15,190 --> 00:04:17,640 but it uses a thicker core size. 129 129 00:04:17,640 --> 00:04:19,240 Now multimode fiber cores 130 130 00:04:19,240 --> 00:04:21,910 are between 50 to 100 microns in diameter. 131 131 00:04:21,910 --> 00:04:24,200 This makes them about 6 to 10 times larger 132 132 00:04:24,200 --> 00:04:26,260 than a single mode fiber's core. 133 133 00:04:26,260 --> 00:04:29,040 Now 50 to 100 microns might sound pretty small, 134 134 00:04:29,040 --> 00:04:30,390 and it is, relatively, 135 135 00:04:30,390 --> 00:04:32,730 I mean, an average human is only about 70 microns 136 136 00:04:32,730 --> 00:04:33,590 in diameter, 137 137 00:04:33,590 --> 00:04:35,550 this is still an increased core size 138 138 00:04:35,550 --> 00:04:37,430 over the size of a single mode fiber, 139 139 00:04:37,430 --> 00:04:40,150 and it allows light to start bouncing around and refracting 140 140 00:04:40,150 --> 00:04:41,880 as it's traveling down the cable. 141 141 00:04:41,880 --> 00:04:43,450 Due to this, multimode fiber 142 142 00:04:43,450 --> 00:04:45,500 is usually going to be used in shorter distances, 143 143 00:04:45,500 --> 00:04:48,160 up to around two kilometers or less in size, 144 144 00:04:48,160 --> 00:04:50,320 and that's about a mile in distance. 145 145 00:04:50,320 --> 00:04:53,160 Now multimode fibers are commonly used in the same place 146 146 00:04:53,160 --> 00:04:55,540 you're going to normally use a copper patch cable. 147 147 00:04:55,540 --> 00:04:57,950 For example, if you're going to be using a multimode fiber 148 148 00:04:57,950 --> 00:04:59,420 to connect a router to a switch, 149 149 00:04:59,420 --> 00:05:02,110 or a switch to a switch, or switches to servers, 150 150 00:05:02,110 --> 00:05:04,110 any place you'd normally use a patch cable, 151 151 00:05:04,110 --> 00:05:05,890 or even a cable run between your patch cable 152 152 00:05:05,890 --> 00:05:06,930 and your wall jack, 153 153 00:05:06,930 --> 00:05:09,810 could be a place you use a multimode fiber instead. 154 154 00:05:09,810 --> 00:05:12,740 For the exam, you do not need to memorize the exact size 155 155 00:05:12,740 --> 00:05:15,340 of the cores for single-mode or multi-mode fibers, 156 156 00:05:15,340 --> 00:05:16,890 they're not going to ask you that. 157 157 00:05:16,890 --> 00:05:19,550 Instead, you need to remember the multi-mode fibers 158 158 00:05:19,550 --> 00:05:21,200 are going to have a larger core size, 159 159 00:05:21,200 --> 00:05:23,720 and therefore they cannot cover longer distances 160 160 00:05:23,720 --> 00:05:25,530 the way a single mode fiber can. 161 161 00:05:25,530 --> 00:05:28,170 If you need to pick out a cable to cover a longer distance, 162 162 00:05:28,170 --> 00:05:31,100 you want to make sure you're selecting a single mode fiber. 163 163 00:05:31,100 --> 00:05:34,060 Remember, single mode fibers have a much smaller core size, 164 164 00:05:34,060 --> 00:05:36,250 and therefore light can only travel in one direction 165 165 00:05:36,250 --> 00:05:37,370 down that cable. 166 166 00:05:37,370 --> 00:05:38,880 When you have a multimode fiber, 167 167 00:05:38,880 --> 00:05:40,080 the light can bounce around more 168 168 00:05:40,080 --> 00:05:41,650 because of the larger core size, 169 169 00:05:41,650 --> 00:05:43,570 and therefore, you're going to have less distance 170 170 00:05:43,570 --> 00:05:46,220 with multimode fiber because you have more noise. 171 171 00:05:46,220 --> 00:05:48,490 This means multimode fibers tend to be less expensive 172 172 00:05:48,490 --> 00:05:49,620 to build and buy, 173 173 00:05:49,620 --> 00:05:52,050 and they're cheaper to install than a single mode fiber. 174 174 00:05:52,050 --> 00:05:53,470 So a lot of network designers 175 175 00:05:53,470 --> 00:05:54,850 will actually implement solutions 176 176 00:05:54,850 --> 00:05:57,370 that use multi-mode fibers over single mode fibers 177 177 00:05:57,370 --> 00:05:58,500 whenever possible. 178 178 00:05:58,500 --> 00:06:01,350 And to do that, they'll make sure they have lower distances. 179 179 00:06:01,350 --> 00:06:03,610 So maybe they'll go 500 meters between switches, 180 180 00:06:03,610 --> 00:06:05,700 instead of two kilometers per switch. 181 181 00:06:05,700 --> 00:06:07,400 Now, if you happen to be working in the field, 182 182 00:06:07,400 --> 00:06:08,790 and you're trying to identify a cable 183 183 00:06:08,790 --> 00:06:11,080 as either a single mode or a multi-mode fiber, 184 184 00:06:11,080 --> 00:06:12,370 the easiest way to do this 185 185 00:06:12,370 --> 00:06:14,590 is by simply looking at the color of the cable. 186 186 00:06:14,590 --> 00:06:16,410 If the cable has a yellow sheath on it, 187 187 00:06:16,410 --> 00:06:18,960 it's a single mode fiber, or SMF cable, 188 188 00:06:18,960 --> 00:06:21,500 if the cable is an aqua blue or orange color sheath, 189 189 00:06:21,500 --> 00:06:24,600 it means it's a multimode fiber, or MMF cable. 190 190 00:06:24,600 --> 00:06:27,590 Now, regardless of whether you use single mode or multimode, 191 191 00:06:27,590 --> 00:06:29,310 you still have to terminate these cables 192 192 00:06:29,310 --> 00:06:30,250 with some kind of a connector, 193 193 00:06:30,250 --> 00:06:32,170 so you can plug them in your devices. 194 194 00:06:32,170 --> 00:06:34,000 Now, there's going to be four different connector types 195 195 00:06:34,000 --> 00:06:35,370 that you're going to come across, 196 196 00:06:35,370 --> 00:06:39,040 SC, ST, LC, and MTRJ. 197 197 00:06:39,040 --> 00:06:41,600 For the exam, you need to be able to visually identify 198 198 00:06:41,600 --> 00:06:42,880 each of these connectors. 199 199 00:06:42,880 --> 00:06:44,380 If I showed you a picture of one, 200 200 00:06:44,380 --> 00:06:45,770 you need to be able to describe it, 201 201 00:06:45,770 --> 00:06:47,580 and pick it out on the exam. 202 202 00:06:47,580 --> 00:06:50,060 So how are you going to remember which one is which? 203 203 00:06:50,060 --> 00:06:51,170 Well, don't worry, 204 204 00:06:51,170 --> 00:06:53,080 I got some memory aids to help you with this, 205 205 00:06:53,080 --> 00:06:54,990 and make sure you get it right on the exam. 206 206 00:06:54,990 --> 00:06:56,880 First, let's look at SC, 207 207 00:06:56,880 --> 00:06:58,850 which stands for subscriber connector. 208 208 00:06:58,850 --> 00:07:01,540 Now SC is fairly popular because they're low cost, 209 209 00:07:01,540 --> 00:07:03,700 they're durable, and they're easy to install. 210 210 00:07:03,700 --> 00:07:05,710 Some people call these the square connector, 211 211 00:07:05,710 --> 00:07:07,220 or the standard connector. 212 212 00:07:07,220 --> 00:07:08,070 But personally, 213 213 00:07:08,070 --> 00:07:10,180 I like to call it the stick and click connector 214 214 00:07:10,180 --> 00:07:12,880 'cause it helps remember what it looks like on exam day. 215 215 00:07:12,880 --> 00:07:15,780 Now, when you look at an SC, or a stick and click connector, 216 216 00:07:15,780 --> 00:07:17,800 you're going to see a little ridge on the top of it, 217 217 00:07:17,800 --> 00:07:19,930 a lot like an RJ45 connector. 218 218 00:07:19,930 --> 00:07:22,970 And when you push the SC into a network jack or wall jack, 219 219 00:07:22,970 --> 00:07:24,300 you're going to hear a little click 220 220 00:07:24,300 --> 00:07:26,380 that tells you it's inserted properly. 221 221 00:07:26,380 --> 00:07:28,550 Now this is why I call it the stick and click, 222 222 00:07:28,550 --> 00:07:30,070 because you stick it into the jack, 223 223 00:07:30,070 --> 00:07:31,420 and you hear the click. 224 224 00:07:31,420 --> 00:07:33,040 With SC, you're usually going to see 225 225 00:07:33,040 --> 00:07:34,540 two cables bundled together, 226 226 00:07:34,540 --> 00:07:36,930 each one with its own SC connector on it, 227 227 00:07:36,930 --> 00:07:39,280 and that way you can plug them into the jack. 228 228 00:07:39,280 --> 00:07:41,380 Each of these cables is going to be used for transmitting, 229 229 00:07:41,380 --> 00:07:42,670 or receiving the data. 230 230 00:07:42,670 --> 00:07:46,230 So to transmit and receive, you need two cables. 231 231 00:07:46,230 --> 00:07:49,410 Next, we have an ST, or straight tip connector. 232 232 00:07:49,410 --> 00:07:52,090 Now the ST connector is also relatively low cost, 233 233 00:07:52,090 --> 00:07:53,270 and easy to use. 234 234 00:07:53,270 --> 00:07:56,050 The ST is one of the older types of fiber characters we have 235 235 00:07:56,050 --> 00:07:59,330 and just like SC, it has a transmit and receive cable, 236 236 00:07:59,330 --> 00:08:01,690 each with its own ST connector on it. 237 237 00:08:01,690 --> 00:08:03,460 I like to call the ST connectors, 238 238 00:08:03,460 --> 00:08:05,040 the stick and twist connector, 239 239 00:08:05,040 --> 00:08:06,730 because you're going to insert it into the jack, 240 240 00:08:06,730 --> 00:08:08,760 and then turn it about half a turn to the right 241 241 00:08:08,760 --> 00:08:10,210 until it locks in place, 242 242 00:08:10,210 --> 00:08:12,760 like a BNC connector does with a copper network. 243 243 00:08:12,760 --> 00:08:15,280 Now, you're not going to hear a click like an SC connector, 244 244 00:08:15,280 --> 00:08:16,950 but you are going to stick it in place, 245 245 00:08:16,950 --> 00:08:19,950 and twist it until it locks and stops turning. 246 246 00:08:19,950 --> 00:08:22,790 Third, we have an LC, or lucent connector. 247 247 00:08:22,790 --> 00:08:25,790 This is a newer and smaller version of an SC connector. 248 248 00:08:25,790 --> 00:08:27,110 Like the SC connector, 249 249 00:08:27,110 --> 00:08:29,910 it does use a stick and click connection to the jack. 250 250 00:08:29,910 --> 00:08:31,560 Now to remember the LC connector, 251 251 00:08:31,560 --> 00:08:33,200 instead of the SC connector, 252 252 00:08:33,200 --> 00:08:35,430 I like to call this the love connector. 253 253 00:08:35,430 --> 00:08:37,160 This is because you're almost always going to find 254 254 00:08:37,160 --> 00:08:38,260 the LC connector 255 255 00:08:38,260 --> 00:08:41,200 with its transmit and receive sides attached side-by-side, 256 256 00:08:41,200 --> 00:08:42,240 like lovers. 257 257 00:08:42,240 --> 00:08:45,130 You can actually place them together and they lock together. 258 258 00:08:45,130 --> 00:08:47,910 Whereas the SC is often found as two individual cables, 259 259 00:08:47,910 --> 00:08:51,300 the LC, or love connector, is almost always married together 260 260 00:08:51,300 --> 00:08:53,760 and they're coupled up right next to each other. 261 261 00:08:53,760 --> 00:08:55,660 Fourth, we have the MTRJ, 262 262 00:08:55,660 --> 00:08:58,000 or mechanical transfer registered jack. 263 263 00:08:58,000 --> 00:09:00,290 MTRJ is a fiber optic cable connector 264 264 00:09:00,290 --> 00:09:03,210 that's very popular and widely used with networking devices 265 265 00:09:03,210 --> 00:09:05,060 because it has a smaller form factor. 266 266 00:09:05,060 --> 00:09:07,440 It's much smaller than the other three we talked about. 267 267 00:09:07,440 --> 00:09:10,070 Each MTRJ connector is going to have both the transmit 268 268 00:09:10,070 --> 00:09:11,570 and receive pins terminated 269 269 00:09:11,570 --> 00:09:13,870 inside a single plastic connector. 270 270 00:09:13,870 --> 00:09:15,350 And this is about half the size 271 271 00:09:15,350 --> 00:09:18,130 of an SC, ST, or LC connector. 272 272 00:09:18,130 --> 00:09:20,270 This means that by using an MTRJ, 273 273 00:09:20,270 --> 00:09:22,840 you can have a switch that fits 24 fiber ports 274 274 00:09:22,840 --> 00:09:24,210 in the same chassis size 275 275 00:09:24,210 --> 00:09:27,730 as a regular RJ45 24 port copper switch, 276 276 00:09:27,730 --> 00:09:29,880 whereas with ST, SC, or LC, 277 277 00:09:29,880 --> 00:09:32,520 you'd only be able to get about 12 switch ports in there. 278 278 00:09:32,520 --> 00:09:35,700 Now, often you're going to see MTRJ used on fiber switches, 279 279 00:09:35,700 --> 00:09:36,533 and they're going to connect 280 280 00:09:36,533 --> 00:09:38,870 to fiber patch distribution panels on one side, 281 281 00:09:38,870 --> 00:09:42,340 and the other side, will convert it to SC, ST, or LC, 282 282 00:09:42,340 --> 00:09:45,150 for distribution out to a wall jack into an office. 283 283 00:09:45,150 --> 00:09:47,420 Now remember, all of these cables are fiber, 284 284 00:09:47,420 --> 00:09:48,760 and they're all made of glass. 285 285 00:09:48,760 --> 00:09:50,780 And when we connect these cables to the connectors, 286 286 00:09:50,780 --> 00:09:52,680 these connectors have two different styles 287 287 00:09:52,680 --> 00:09:54,630 that we can contact with those jacks. 288 288 00:09:54,630 --> 00:09:56,530 The main difference between these two styles 289 289 00:09:56,530 --> 00:09:58,690 is how the fibers end face looks. 290 290 00:09:58,690 --> 00:10:00,160 Now, what are these two options? 291 291 00:10:00,160 --> 00:10:02,760 Well, they're APC, and UPC. 292 292 00:10:02,760 --> 00:10:06,520 First, we have APC, the angled physical contact connector. 293 293 00:10:06,520 --> 00:10:08,600 With APC, the fiber end face 294 294 00:10:08,600 --> 00:10:10,540 is posed at an eight degree angle. 295 295 00:10:10,540 --> 00:10:12,620 This angled face means that the reflected light 296 296 00:10:12,620 --> 00:10:14,120 is going to reflected at an angle 297 297 00:10:14,120 --> 00:10:15,560 into the clouding of the cable, 298 298 00:10:15,560 --> 00:10:18,250 instead of straight back down towards the source of light. 299 299 00:10:18,250 --> 00:10:21,410 This provides a better overall signal with less noise. 300 300 00:10:21,410 --> 00:10:25,100 Next, we have UPC, or the ultra physical contact connector. 301 301 00:10:25,100 --> 00:10:28,440 With UPC, the fiber end face is posed with no angling, 302 302 00:10:28,440 --> 00:10:30,450 and instead it has more of a curvature to it 303 303 00:10:30,450 --> 00:10:31,490 for better core alignment 304 304 00:10:31,490 --> 00:10:33,550 when it goes and gets plugged into a jack. 305 305 00:10:33,550 --> 00:10:35,100 Because of this lack of an angle, 306 306 00:10:35,100 --> 00:10:37,640 reflected light is going to be reflected straight back down 307 307 00:10:37,640 --> 00:10:40,050 towards the light source, and it creates more noise., 308 308 00:10:40,050 --> 00:10:41,800 and this causes a bit of signal loss 309 309 00:10:41,800 --> 00:10:44,010 over a regular APC connector. 310 310 00:10:44,010 --> 00:10:46,010 In general, you're going to see SC connectors 311 311 00:10:46,010 --> 00:10:50,210 like to use APC more, while MTRJ tends to use UPC more. 312 312 00:10:50,210 --> 00:10:51,300 If you're working in the field, 313 313 00:10:51,300 --> 00:10:54,270 and trying to identify a connector as either APC or UPC, 314 314 00:10:54,270 --> 00:10:55,570 the easiest way of doing that 315 315 00:10:55,570 --> 00:10:57,640 is by looking at the color on the connector. 316 316 00:10:57,640 --> 00:11:00,290 If the connector is green, it's APC, 317 317 00:11:00,290 --> 00:11:02,970 if the connector is blue, it's UPC. 318 318 00:11:02,970 --> 00:11:04,830 Now, the final thing we need to discuss 319 319 00:11:04,830 --> 00:11:07,380 is wavelength division multiplexing technologies, 320 320 00:11:07,380 --> 00:11:09,110 and these are used with fiber optic cables 321 321 00:11:09,110 --> 00:11:11,840 to get more things going over the same line. 322 322 00:11:11,840 --> 00:11:14,380 Now, because fiber optics originally used a single light 323 323 00:11:14,380 --> 00:11:16,450 to send data down a single fiber core, 324 324 00:11:16,450 --> 00:11:19,950 we can only send one zero or one one at a time. 325 325 00:11:19,950 --> 00:11:21,840 When the light was on, we got a one, 326 326 00:11:21,840 --> 00:11:23,510 when we had it off, we got a zero. 327 327 00:11:23,510 --> 00:11:25,210 And so we were sending one bit at a time, 328 328 00:11:25,210 --> 00:11:27,350 but we could turn it on and off very fast. 329 329 00:11:27,350 --> 00:11:29,230 Now, we also couldn't send or receive things 330 330 00:11:29,230 --> 00:11:30,480 over the same cable. 331 331 00:11:30,480 --> 00:11:32,390 So we had to have a dedicated cable for sending, 332 332 00:11:32,390 --> 00:11:33,990 and another one for receiving, 333 333 00:11:33,990 --> 00:11:35,740 otherwise, the light wouldn't be able to tell 334 334 00:11:35,740 --> 00:11:37,280 who is sending and who's receiving, 335 335 00:11:37,280 --> 00:11:40,050 and we would just see the single light being on or off 336 336 00:11:40,050 --> 00:11:41,870 over that single strand of fiber. 337 337 00:11:41,870 --> 00:11:43,420 Well, to solve this issue, 338 338 00:11:43,420 --> 00:11:45,730 wavelength division multiplexing was created. 339 339 00:11:45,730 --> 00:11:48,520 Now, wavelength division multiplexing, or WDM, 340 340 00:11:48,520 --> 00:11:50,740 is a technology that allows multiple signals 341 341 00:11:50,740 --> 00:11:52,240 to be combined into one signal, 342 342 00:11:52,240 --> 00:11:54,540 and then sent over a single fiber optic strand 343 343 00:11:54,540 --> 00:11:57,220 using different wavelengths for the laser light source. 344 344 00:11:57,220 --> 00:11:58,360 Now, by doing this, 345 345 00:11:58,360 --> 00:12:00,610 bi-directional communications over a single strand 346 346 00:12:00,610 --> 00:12:01,690 can be accomplished, 347 347 00:12:01,690 --> 00:12:04,550 as well as an increase in bandwidth and capacity. 348 348 00:12:04,550 --> 00:12:07,530 Now at its core, WDM systems use a multiplexer 349 349 00:12:07,530 --> 00:12:10,520 at the transmitter to join several light signals together, 350 350 00:12:10,520 --> 00:12:12,540 and then it sends it across the fiber. 351 351 00:12:12,540 --> 00:12:13,850 When it gets to the other side, 352 352 00:12:13,850 --> 00:12:16,230 it's going to use a demultiplexer at the receiver 353 353 00:12:16,230 --> 00:12:19,360 to split that signal back out into the multiple signals. 354 354 00:12:19,360 --> 00:12:21,240 Most wavelength division multiplexing 355 355 00:12:21,240 --> 00:12:22,910 is run over single mode fibers, 356 356 00:12:22,910 --> 00:12:24,870 but there are a few types of WDM 357 357 00:12:24,870 --> 00:12:27,130 that can run over multimode as well. 358 358 00:12:27,130 --> 00:12:29,430 Now, there are two main types of WDM 359 359 00:12:29,430 --> 00:12:33,830 that we need to talk about, namely, CWDM and DWDM. 360 360 00:12:33,830 --> 00:12:35,800 The first type is CWDM, 361 361 00:12:35,800 --> 00:12:38,700 and this stands for coarse wavelength division multiplexing. 362 362 00:12:38,700 --> 00:12:40,490 Coarse wavelength division multiplexing 363 363 00:12:40,490 --> 00:12:43,330 can support up to 18 wavelength channels being transmitted 364 364 00:12:43,330 --> 00:12:44,900 over a single fiber. 365 365 00:12:44,900 --> 00:12:45,870 To achieve this, 366 366 00:12:45,870 --> 00:12:48,490 each of these wavelengths is set 20 nanometers apart 367 367 00:12:48,490 --> 00:12:49,750 on their own channel. 368 368 00:12:49,750 --> 00:12:53,210 Now, CWDM is used mainly in shorter distance applications 369 369 00:12:53,210 --> 00:12:55,080 up to about 70 kilometers. 370 370 00:12:55,080 --> 00:12:57,300 Now, if you're going to be above 40 kilometers, 371 371 00:12:57,300 --> 00:12:58,780 but under 70 kilometers, 372 372 00:12:58,780 --> 00:13:01,400 you can only support 8 of those 18 channels 373 373 00:13:01,400 --> 00:13:02,850 because the longer distance you go, 374 374 00:13:02,850 --> 00:13:04,370 the more the light starts spreading out, 375 375 00:13:04,370 --> 00:13:06,150 and it causes noise over the channels, 376 376 00:13:06,150 --> 00:13:07,830 so you need more separation. 377 377 00:13:07,830 --> 00:13:09,900 Now, CWDM does support speeds 378 378 00:13:09,900 --> 00:13:11,860 up to 10 gigabits per second for ethernet, 379 379 00:13:11,860 --> 00:13:13,620 and up to 16 gigabits per second 380 380 00:13:13,620 --> 00:13:15,550 for fiber channel installations. 381 381 00:13:15,550 --> 00:13:18,520 CWDM is sometimes used to connect routers and switches 382 382 00:13:18,520 --> 00:13:20,880 using GBIC or SFF transceivers, 383 383 00:13:20,880 --> 00:13:23,310 to connect switches and routers over longer distances 384 384 00:13:23,310 --> 00:13:25,380 then you could using a copper cable. 385 385 00:13:25,380 --> 00:13:27,750 The second type we have is DWDM, 386 386 00:13:27,750 --> 00:13:30,770 and this stands for dense wavelength division multiplexing. 387 387 00:13:30,770 --> 00:13:33,970 Now it's called D for dense, because we have DWDM, 388 388 00:13:33,970 --> 00:13:36,270 that's used to support 80 wavelength channels, 389 389 00:13:36,270 --> 00:13:39,200 all being transmitted simultaneously over a single fiber, 390 390 00:13:39,200 --> 00:13:40,920 that's right, eight zero, 80, 391 391 00:13:40,920 --> 00:13:42,900 instead of one eight, 18. 392 392 00:13:42,900 --> 00:13:44,130 Now each of these wavelengths 393 393 00:13:44,130 --> 00:13:47,000 is set on a channel only 0.8 nanometers apart, 394 394 00:13:47,000 --> 00:13:48,770 and this makes them very dense 395 395 00:13:48,770 --> 00:13:50,780 because we don't have 20 nanometers of separation 396 396 00:13:50,780 --> 00:13:52,050 like we did with coarse, 397 397 00:13:52,050 --> 00:13:53,760 instead we have 0.8 nanometers, 398 398 00:13:53,760 --> 00:13:55,640 and that's why we call it dense, 399 399 00:13:55,640 --> 00:13:57,680 dense wavelength division multiplexing 400 400 00:13:57,680 --> 00:14:00,610 because of the denseness and closeness of these channels. 401 401 00:14:00,610 --> 00:14:03,070 Now, DWDM is used to transport data 402 402 00:14:03,070 --> 00:14:04,790 over much longer distances 403 403 00:14:04,790 --> 00:14:07,100 because these connections can also be amplified 404 404 00:14:07,100 --> 00:14:08,870 as we're going across the cable. 405 405 00:14:08,870 --> 00:14:10,700 Now, since there are more channels being used, 406 406 00:14:10,700 --> 00:14:13,730 DWDM can handle a lot higher speeds as well, 407 407 00:14:13,730 --> 00:14:16,260 with top speeds of up to 100 gigabits per second 408 408 00:14:16,260 --> 00:14:17,170 per channel, 409 409 00:14:17,170 --> 00:14:20,830 and remember, DWDM can handle up to 80 channels, 410 410 00:14:20,830 --> 00:14:23,530 therefore, we can have a maximum theoretical speed 411 411 00:14:23,530 --> 00:14:26,830 of up to eight terabits per second, over a single cable. 412 412 00:14:26,830 --> 00:14:30,600 So where might you find yourself using DWDM? 413 413 00:14:30,600 --> 00:14:33,420 Well, if you work for a major internet service provider, 414 414 00:14:33,420 --> 00:14:35,280 or a telecommunication service provider, 415 415 00:14:35,280 --> 00:14:37,770 you may find yourself working with this type of equipment, 416 416 00:14:37,770 --> 00:14:38,710 but you're not going to find it 417 417 00:14:38,710 --> 00:14:40,880 in your traditional small office, home office, 418 418 00:14:40,880 --> 00:14:42,870 or even corporate office environments. 419 419 00:14:42,870 --> 00:14:45,550 These types of solutions are extremely expensive. 420 420 00:14:45,550 --> 00:14:48,050 And so they're mainly used as part of the internet backbone 421 421 00:14:48,050 --> 00:14:51,060 for large service providers who are running SONET systems. 422 422 00:14:51,060 --> 00:14:52,160 For most of us though, 423 423 00:14:52,160 --> 00:14:54,400 we're going to be limited to using CWDM, 424 424 00:14:54,400 --> 00:14:56,820 which comes embedded into some of our switches and routers 425 425 00:14:56,820 --> 00:14:58,850 when we're using fiber for our tracking pass, 426 426 00:14:58,850 --> 00:15:00,600 or our connections between devices.