1 1 00:00:00,227 --> 00:00:02,350 IPv6 addressing. 2 2 00:00:02,350 --> 00:00:04,840 In this lesson, we're going to introduce the concept 3 3 00:00:04,840 --> 00:00:08,900 surrounding IPv6 or Internet Protocol version six. 4 4 00:00:08,900 --> 00:00:11,090 So up to this point, we've really just talked 5 5 00:00:11,090 --> 00:00:13,970 about IPv4 including how to subnet it, 6 6 00:00:13,970 --> 00:00:16,760 but one of the problems that we have with IPv4 7 7 00:00:16,760 --> 00:00:19,250 is that it's limited in its address space. 8 8 00:00:19,250 --> 00:00:21,100 This is because there are only 32 bits 9 9 00:00:21,100 --> 00:00:23,130 that make up an IPv4 address, 10 10 00:00:23,130 --> 00:00:26,810 giving us only 4.2 billion possible address combinations. 11 11 00:00:26,810 --> 00:00:30,150 Now I know 4.2 billion sounds like a whole lot of IPs, 12 12 00:00:30,150 --> 00:00:32,690 but when we took out entire portions of things 13 13 00:00:32,690 --> 00:00:34,530 for things like IP put addresses, 14 14 00:00:34,530 --> 00:00:37,040 local host addresses, private IPs 15 15 00:00:37,040 --> 00:00:38,500 and then there was a huge amount of waste 16 16 00:00:38,500 --> 00:00:40,460 before you even started to use subnetting, 17 17 00:00:40,460 --> 00:00:43,590 this led to a big issue and we began to start running 18 18 00:00:43,590 --> 00:00:46,560 out of network addresses inside of IPv4. 19 19 00:00:46,560 --> 00:00:50,610 This is known as address exhaustion and it is a real thing. 20 20 00:00:50,610 --> 00:00:53,010 In fact, in November of 2019, 21 21 00:00:53,010 --> 00:00:56,280 RIPE NCC, the Regional Internet Registry for Europe, 22 22 00:00:56,280 --> 00:00:57,917 West Asia and the former USSR, 23 23 00:00:57,917 --> 00:00:59,880 announced they have already exhausted 24 24 00:00:59,880 --> 00:01:02,880 its entire pool of IPv4 addresses. 25 25 00:01:02,880 --> 00:01:06,670 Luckily though, the Internet Engineering Task Force or IETF 26 26 00:01:06,670 --> 00:01:08,480 had already started looking into the future 27 27 00:01:08,480 --> 00:01:10,950 and they developed IPv6 as a standard 28 28 00:01:10,950 --> 00:01:13,430 all the way back in 1995 29 29 00:01:13,430 --> 00:01:17,110 with an RFC that documented their vision for IPv6 30 30 00:01:17,110 --> 00:01:21,530 which they termed IP Next Generation or IPng. 31 31 00:01:21,530 --> 00:01:26,530 Now you see IPv6 is actually a huge improvement over IPv4 32 32 00:01:26,600 --> 00:01:29,030 in terms of the number of addresses available. 33 33 00:01:29,030 --> 00:01:32,397 Instead of using a 32-bit address like we do in IPv4, 34 34 00:01:32,397 --> 00:01:35,830 IPv6 going to use 128-bit address. 35 35 00:01:35,830 --> 00:01:39,260 This is going to give you a much larger address space. 36 36 00:01:39,260 --> 00:01:41,340 In fact, it's going to give you a possibility 37 37 00:01:41,340 --> 00:01:45,170 of 340 undecillion IP addresses. 38 38 00:01:45,170 --> 00:01:47,520 That is enough IP addresses for every man, 39 39 00:01:47,520 --> 00:01:49,670 woman and child on the planet. 40 40 00:01:49,670 --> 00:01:52,300 This is two to the 128th power. 41 41 00:01:52,300 --> 00:01:55,040 In fact, there are many, many IP addresses 42 42 00:01:55,040 --> 00:01:57,450 for each man, woman and child on the planet 43 43 00:01:57,450 --> 00:02:00,000 because there are so many IP addresses available. 44 44 00:02:00,000 --> 00:02:01,710 Now you might be wondering to yourself, 45 45 00:02:01,710 --> 00:02:04,970 hey, we went from IPv4 to IPv6. 46 46 00:02:04,970 --> 00:02:06,840 What happened to version five? 47 47 00:02:06,840 --> 00:02:09,130 Why did we jump straight to version six? 48 48 00:02:09,130 --> 00:02:11,130 Well version five was created, 49 49 00:02:11,130 --> 00:02:14,070 but it was never fully adopted as an official protocol 50 50 00:02:14,070 --> 00:02:17,080 or standard and therefore it never went into production. 51 51 00:02:17,080 --> 00:02:19,000 Instead, a lot of those concepts that were developed 52 52 00:02:19,000 --> 00:02:21,710 under version five because it was an experimental protocol, 53 53 00:02:21,710 --> 00:02:23,640 were then brought into IPv6 54 54 00:02:23,640 --> 00:02:25,600 when it became an official standard. 55 55 00:02:25,600 --> 00:02:29,380 So let's talk about the benefits of IPv6. 56 56 00:02:29,380 --> 00:02:30,660 One of the biggest benefits 57 57 00:02:30,660 --> 00:02:32,630 is that much larger address space 58 58 00:02:32,630 --> 00:02:35,100 because of the 128-bit addresses. 59 59 00:02:35,100 --> 00:02:36,200 In addition to that, 60 60 00:02:36,200 --> 00:02:38,910 IPv6 also increased the efficiency of our networks 61 61 00:02:38,910 --> 00:02:42,470 by removing IPv4's broadcast data flow type. 62 62 00:02:42,470 --> 00:02:44,980 Now IPv6 is also more secure 63 63 00:02:44,980 --> 00:02:47,750 because there is no packet or datagram fragmentation 64 64 00:02:47,750 --> 00:02:49,800 within the IPv6 standard. 65 65 00:02:49,800 --> 00:02:51,880 There's also no maximum transmission units 66 66 00:02:51,880 --> 00:02:53,830 for discovery within each session 67 67 00:02:53,830 --> 00:02:56,470 unlike IPv4 which contained an MTU 68 68 00:02:56,470 --> 00:02:58,620 with a certain size for each packet. 69 69 00:02:58,620 --> 00:03:01,410 In IPv4, if I sent you a packet that was larger 70 70 00:03:01,410 --> 00:03:03,550 than your maximum transmission unit size, 71 71 00:03:03,550 --> 00:03:04,820 it would actually fragment that 72 72 00:03:04,820 --> 00:03:06,160 and send it over the network. 73 73 00:03:06,160 --> 00:03:07,860 And then when it reached its destination, 74 74 00:03:07,860 --> 00:03:09,720 it would be reassembled and read. 75 75 00:03:09,720 --> 00:03:11,430 This was actually a security risk. 76 76 00:03:11,430 --> 00:03:13,230 It also required extra processing 77 77 00:03:13,230 --> 00:03:15,210 and it could actually slow down your networks 78 78 00:03:15,210 --> 00:03:17,660 because it become a very inefficient way of doing things 79 79 00:03:17,660 --> 00:03:18,860 in our modern networks 80 80 00:03:18,860 --> 00:03:20,800 with higher internet connection speeds. 81 81 00:03:20,800 --> 00:03:23,560 So with IPv6, they decided to do away 82 82 00:03:23,560 --> 00:03:25,620 with fragmentation completely. 83 83 00:03:25,620 --> 00:03:28,210 Now in addition to providing all of these new benefits, 84 84 00:03:28,210 --> 00:03:30,630 the creators of IPv6 were also very smart 85 85 00:03:30,630 --> 00:03:34,430 and realized that IPv6, to be embraced and accepted fully, 86 86 00:03:34,430 --> 00:03:37,330 it would have to be backwards compatible with IPv4 87 87 00:03:37,330 --> 00:03:42,330 and allow both IPv6 and IPv4 to coexist on the same network. 88 88 00:03:42,470 --> 00:03:45,220 After all, it was already late in 1990s 89 89 00:03:45,220 --> 00:03:47,600 when IPv6 was being developed and released 90 90 00:03:47,600 --> 00:03:49,020 and lots of computer networks 91 91 00:03:49,020 --> 00:03:51,230 were already feel it all over the globe. 92 92 00:03:51,230 --> 00:03:52,650 So it would not be feasible 93 93 00:03:52,650 --> 00:03:55,670 for us to simply change over everything in a single day. 94 94 00:03:55,670 --> 00:03:57,230 Think about it like the current migration 95 95 00:03:57,230 --> 00:03:58,063 we're going through 96 96 00:03:58,063 --> 00:04:00,480 from gas powered to electric power vehicles. 97 97 00:04:00,480 --> 00:04:02,660 This is happening throughout the entire 2020s 98 98 00:04:02,660 --> 00:04:04,180 and into 2030s. 99 99 00:04:04,180 --> 00:04:06,700 Now this would be an impossible thing for us to say, 100 100 00:04:06,700 --> 00:04:09,580 hey, everybody on January 1st 2025, 101 101 00:04:09,580 --> 00:04:11,430 no one can use gas powered vehicles anymore. 102 102 00:04:11,430 --> 00:04:13,500 All of them we'll replace with electric vehicles 103 103 00:04:13,500 --> 00:04:14,740 as of that date. 104 104 00:04:14,740 --> 00:04:15,940 If a government tried to do that, 105 105 00:04:15,940 --> 00:04:17,900 they'd probably have a revolution on their hands 106 106 00:04:17,900 --> 00:04:20,910 because so many people already own gas powered cars 107 107 00:04:20,910 --> 00:04:23,560 and spent a ton of money and investing into those cars 108 108 00:04:23,560 --> 00:04:25,640 and infrastructure to support them. 109 109 00:04:25,640 --> 00:04:28,230 Now for that reason, we're not going to simply replace 110 110 00:04:28,230 --> 00:04:30,080 all gas powered cars overnight. 111 111 00:04:30,080 --> 00:04:32,430 Instead, there's going to be this slow transition 112 112 00:04:32,430 --> 00:04:35,850 from gas power to electric that goes on by 2030 113 113 00:04:35,850 --> 00:04:38,650 or maybe 2040 as more and more of the newer cars 114 114 00:04:38,650 --> 00:04:40,780 sold in the world will be sold as electric 115 115 00:04:40,780 --> 00:04:43,150 and they'll stop selling gas power vehicles. 116 116 00:04:43,150 --> 00:04:46,660 Well the exact same thing is going on with IPv6. 117 117 00:04:46,660 --> 00:04:50,740 So IPv6 allows for both IPv4 and IPv6 118 118 00:04:50,740 --> 00:04:52,870 to co-exist on the same networks 119 119 00:04:52,870 --> 00:04:55,110 and the equipment that runs these networks 120 120 00:04:55,110 --> 00:04:58,110 becomes known as dual stack which simply means 121 121 00:04:58,110 --> 00:05:01,930 they can run both IPv4 protocols and IPv6 protocols 122 122 00:05:01,930 --> 00:05:04,830 on the same network devices simultaneously. 123 123 00:05:04,830 --> 00:05:08,170 With dual stack devices, if a client supports IPv6, 124 124 00:05:08,170 --> 00:05:10,660 the router or switch would prefer to use IPv6 125 125 00:05:10,660 --> 00:05:12,480 and we'll talk under that method. 126 126 00:05:12,480 --> 00:05:15,090 Now if a device is not able to support IPv6, 127 127 00:05:15,090 --> 00:05:16,810 it flips itself back and says, 128 128 00:05:16,810 --> 00:05:20,130 okay, I'll talk to you using the older IPv4 protocol. 129 129 00:05:20,130 --> 00:05:22,130 This way I can still support you. 130 130 00:05:22,130 --> 00:05:24,600 Another method that we use is known as tunneling. 131 131 00:05:24,600 --> 00:05:28,510 This is where IPv6 is going to be tunneled over an IPv4 device. 132 132 00:05:28,510 --> 00:05:30,860 This allows your older IPv4 routers 133 133 00:05:30,860 --> 00:05:33,340 to still carry IPv6 traffic. 134 134 00:05:33,340 --> 00:05:36,270 IPv6 is essentially going to be tunneled as a mechanism 135 135 00:05:36,270 --> 00:05:40,260 for encapsulating the IPv6 packets within IPv4 headers 136 136 00:05:40,260 --> 00:05:43,940 and carrying this IPv6 data over those IPv4 routers 137 137 00:05:43,940 --> 00:05:46,240 and other infrastructure that already exists. 138 138 00:05:46,240 --> 00:05:48,410 It does this by creating a point-to-point tunnel 139 139 00:05:48,410 --> 00:05:50,140 between the source and destination 140 140 00:05:50,140 --> 00:05:52,200 and then encapsulating that information. 141 141 00:05:52,200 --> 00:05:55,360 This allows isolated IPv6 clients and servers 142 142 00:05:55,360 --> 00:05:57,040 to be able to communicate without needing to upgrade 143 143 00:05:57,040 --> 00:05:59,360 all of the routers and switch infrastructure 144 144 00:05:59,360 --> 00:06:02,780 that still uses IPv4 that may exist between them. 145 145 00:06:02,780 --> 00:06:06,610 Now one day we may eventually see IPv4 retired fully, 146 146 00:06:06,610 --> 00:06:09,410 but so far it hasn't happened and personally, 147 147 00:06:09,410 --> 00:06:11,160 I'm not holding my breath. 148 148 00:06:11,160 --> 00:06:13,950 From some articles I've read, predictions are that IPv4 149 149 00:06:13,950 --> 00:06:16,840 will remain with us until at least 2040 150 150 00:06:16,840 --> 00:06:19,040 so you're going to have to know how to work with both 151 151 00:06:19,040 --> 00:06:22,730 IPv4 and IPv6 for the foreseeable future 152 152 00:06:22,730 --> 00:06:24,400 as a network technician. 153 153 00:06:24,400 --> 00:06:27,880 Another benefit of IPv6 is that it has a simplified header. 154 154 00:06:27,880 --> 00:06:30,580 So instead of those 12 fields that we had in IPv4, 155 155 00:06:30,580 --> 00:06:33,180 we only have five fields in IPv6 156 156 00:06:33,180 --> 00:06:34,680 making it a slimmed down header 157 157 00:06:34,680 --> 00:06:37,380 that is a lot more efficient to send over our networks. 158 158 00:06:37,380 --> 00:06:41,670 So you may be wondering what does an IPv6 header look like. 159 159 00:06:41,670 --> 00:06:44,240 Well I'm going to show it to you, but please realize 160 160 00:06:44,240 --> 00:06:46,490 you don't need to memorize this for the exam. 161 161 00:06:46,490 --> 00:06:48,690 Instead, this is just to show you the different fields 162 162 00:06:48,690 --> 00:06:50,770 that were in IPv4 which is on top 163 163 00:06:50,770 --> 00:06:52,940 versus IPv6 which is on bottom. 164 164 00:06:52,940 --> 00:06:54,970 And now you can see how much more simple 165 165 00:06:54,970 --> 00:06:58,210 IPv6 really is over IPv4. 166 166 00:06:58,210 --> 00:06:59,940 Alright, let's get back to some things 167 167 00:06:59,940 --> 00:07:01,920 that you do need to understand for the exam. 168 168 00:07:01,920 --> 00:07:05,330 Like what does an IPv6 address actually look like. 169 169 00:07:05,330 --> 00:07:08,310 Well I already said that it's 128 bits in length 170 170 00:07:08,310 --> 00:07:11,890 so that means it would have 128 ones or zeros 171 171 00:07:11,890 --> 00:07:13,350 if we wrote it out in binary 172 172 00:07:13,350 --> 00:07:15,670 and that seems like a really bad idea to me. 173 173 00:07:15,670 --> 00:07:17,130 So we're not going to do that. 174 174 00:07:17,130 --> 00:07:18,960 Now we could use dotted decimal notation 175 175 00:07:18,960 --> 00:07:20,430 like we did an IPv4, 176 176 00:07:20,430 --> 00:07:22,740 but that still will be a lot of octets to write out 177 177 00:07:22,740 --> 00:07:27,400 because we would need 16 octets to represent all 128 bits. 178 178 00:07:27,400 --> 00:07:30,040 So to solve this problem, the IETF 179 179 00:07:30,040 --> 00:07:33,030 decided that we should use hexadecimal digits instead. 180 180 00:07:33,030 --> 00:07:35,610 You see, hexadecimal is base 16 181 181 00:07:35,610 --> 00:07:37,520 which you may or may not remember from your high school 182 182 00:07:37,520 --> 00:07:38,730 algebra classes. 183 183 00:07:38,730 --> 00:07:41,140 Now in hexadecimal, each hexadecimal digit 184 184 00:07:41,140 --> 00:07:43,410 is actually four bits and this is going to allow us 185 185 00:07:43,410 --> 00:07:45,000 to represent an IPv6 address 186 186 00:07:45,000 --> 00:07:47,450 by combining four hexadecimal digits together 187 187 00:07:47,450 --> 00:07:49,520 to make up what we call a segment. 188 188 00:07:49,520 --> 00:07:52,460 Now a segment is going to have 16 bits in it. 189 189 00:07:52,460 --> 00:07:54,770 This is represented by those four hexadecimal digits 190 190 00:07:54,770 --> 00:07:56,190 and then we're going to add a colon 191 191 00:07:56,190 --> 00:07:57,610 and then we're going to keep adding segments 192 192 00:07:57,610 --> 00:08:00,010 until we get up to 128 bits 193 193 00:08:00,010 --> 00:08:01,640 which is going to take eight segments, 194 194 00:08:01,640 --> 00:08:04,270 each of those having four hexadecimal digits each. 195 195 00:08:04,270 --> 00:08:07,230 This gives me a total of 32 hexadecimal digits 196 196 00:08:07,230 --> 00:08:09,200 which is still pretty long. 197 197 00:08:09,200 --> 00:08:13,060 Now with 128 bits being represented in an IPv6 address, 198 198 00:08:13,060 --> 00:08:16,570 this means we will have no more than 32 hexadecimal digits 199 199 00:08:16,570 --> 00:08:18,440 inside of all these segments. 200 200 00:08:18,440 --> 00:08:21,890 Now why did I say no more than 32 digits in length 201 201 00:08:21,890 --> 00:08:24,010 for the total of these eight segments? 202 202 00:08:24,010 --> 00:08:26,550 Why wouldn't it just be 32 hexadecimal digits 203 203 00:08:26,550 --> 00:08:29,460 because 32 digits times four bits per digit 204 204 00:08:29,460 --> 00:08:32,040 would give us 128 bits? 205 205 00:08:32,040 --> 00:08:35,290 Well this is because IPv6 actually allows us to use 206 206 00:08:35,290 --> 00:08:37,210 a shorthand to be able to simplify 207 207 00:08:37,210 --> 00:08:39,620 our very long IPv6 addresses. 208 208 00:08:39,620 --> 00:08:41,710 Now the rules of shorthand are really important 209 209 00:08:41,710 --> 00:08:44,400 because you could see exam questions on these. 210 210 00:08:44,400 --> 00:08:46,740 So if you have four zeros for a segment, 211 211 00:08:46,740 --> 00:08:49,100 you can actually put one zero there instead 212 212 00:08:49,100 --> 00:08:51,030 and drop those leading zeros. 213 213 00:08:51,030 --> 00:08:54,550 For example, let's pretend I have a really long IPv6 address 214 214 00:08:54,550 --> 00:08:59,550 of 2018:0000:0000:0000:0000:0000:4815:54ae. 215 215 00:09:08,210 --> 00:09:11,110 Using this simple rule, I can replace all those segments 216 216 00:09:11,110 --> 00:09:13,570 that have multiple zeros with a single zero. 217 217 00:09:13,570 --> 00:09:18,570 This would give me 2018:0:0:0:0:0:4815:54ae. 218 218 00:09:23,330 --> 00:09:26,420 Alright, this reduced my number of hexadecimal digits 219 219 00:09:26,420 --> 00:09:30,540 down from 32 to just 17 so it's about half the length. 220 220 00:09:30,540 --> 00:09:33,270 We're getting better, but I'm not going to stop there. 221 221 00:09:33,270 --> 00:09:34,460 There's another rule I can use 222 222 00:09:34,460 --> 00:09:36,720 in the world of IPv6 shorthand. 223 223 00:09:36,720 --> 00:09:39,050 This rule says that if there are multiple segments 224 224 00:09:39,050 --> 00:09:40,550 that all have zeros in them 225 225 00:09:40,550 --> 00:09:43,160 and no other hex digits are being represented there, 226 226 00:09:43,160 --> 00:09:45,820 I can summarize that by using a double colon 227 227 00:09:45,820 --> 00:09:47,880 and take out all those zeros. 228 228 00:09:47,880 --> 00:09:50,240 Now this rule is special because you can only do 229 229 00:09:50,240 --> 00:09:54,190 the double colon thing one time inside an IPv6 address. 230 230 00:09:54,190 --> 00:09:57,380 So using my double colon rule, I can summarize 231 231 00:09:57,380 --> 00:10:02,223 232 2018:0:0:0:0:0:4815:54ae 232 233 00:10:04,510 --> 00:10:07,070 into removing all those five sets of zeros 233 234 00:10:07,070 --> 00:10:08,670 and replacing them with a double colon 234 235 00:10:08,670 --> 00:10:11,590 and getting myself 2018::4815:54ae. 235 236 00:10:14,020 --> 00:10:16,740 So I went from 32 hexadecimal digits 236 237 00:10:16,740 --> 00:10:18,600 down to 17 hexadecimal digits. 237 238 00:10:18,600 --> 00:10:20,870 and now I'm down from 17 digits 238 239 00:10:20,870 --> 00:10:22,830 all the way down to 12 digits. 239 240 00:10:22,830 --> 00:10:25,430 Much smaller, much easier to work with. 240 241 00:10:25,430 --> 00:10:27,970 You can see how this shorthand is really helpful. 241 242 00:10:27,970 --> 00:10:30,880 So how are you going to recognize an IPv6 address 242 243 00:10:30,880 --> 00:10:32,700 versus an IPv4 address? 243 244 00:10:32,700 --> 00:10:35,880 Well the first way is by looking at what IPv4 is. 244 245 00:10:35,880 --> 00:10:39,130 IPv4 is always going to use the dotted decimal notation 245 246 00:10:39,130 --> 00:10:40,750 using four octets. 246 247 00:10:40,750 --> 00:10:42,210 Now IPv6 on the other hand 247 248 00:10:42,210 --> 00:10:44,270 is going to use colons between its numbers 248 249 00:10:44,270 --> 00:10:46,180 and it's going to be written in hexadecimal. 249 250 00:10:46,180 --> 00:10:49,530 Alright, now one of the questions you might see on test day 250 251 00:10:49,530 --> 00:10:52,830 is to identify an IPv6 address when you see one. 251 252 00:10:52,830 --> 00:10:54,910 For example, you might get a question like 252 253 00:10:54,910 --> 00:10:57,410 which of the following is an IPv6 address? 253 254 00:10:57,410 --> 00:10:59,150 This would be a fair question to ask you. 254 255 00:10:59,150 --> 00:11:03,020 You're going to get some options like 192.168.1.1 255 256 00:11:03,020 --> 00:11:05,540 which we know isn't it because that's an IPv4 address. 256 257 00:11:05,540 --> 00:11:10,540 You're going to get 12:34:56:78:90:AB or 1234::5678:90AB. 257 258 00:11:15,740 --> 00:11:18,860 So wait a minute, those last two I just said, 258 259 00:11:18,860 --> 00:11:20,750 they're really similar, aren't they? 259 260 00:11:20,750 --> 00:11:24,060 Yes, but only one of those is a valid IPv6 address. 260 261 00:11:24,060 --> 00:11:25,360 Do you know which one it is? 261 262 00:11:25,360 --> 00:11:27,730 Because most students get confused here. 262 263 00:11:27,730 --> 00:11:31,740 Now the second option here is actually not an IPv6 address. 263 264 00:11:31,740 --> 00:11:33,560 Instead it's a MAC address. 264 265 00:11:33,560 --> 00:11:35,890 Remember, MAC addresses which are a layer two 265 266 00:11:35,890 --> 00:11:37,780 physical addresses are always going to have 266 267 00:11:37,780 --> 00:11:40,970 12 hexadecimal digits and separated by colons. 267 268 00:11:40,970 --> 00:11:42,940 Usually they're going to be written as six groups 268 269 00:11:42,940 --> 00:11:45,570 of two digits each and each of those are going to be separated 269 270 00:11:45,570 --> 00:11:46,950 by a single colon. 270 271 00:11:46,950 --> 00:11:48,940 An IPv6 address on the other hand, 271 272 00:11:48,940 --> 00:11:51,870 should always be written in segments of four digits each 272 273 00:11:51,870 --> 00:11:54,340 and they should always have 16 segments 273 274 00:11:54,340 --> 00:11:56,710 unless you see a double colon. 274 275 00:11:56,710 --> 00:11:58,810 In this example, we have a double colon 275 276 00:11:58,810 --> 00:12:01,750 between the first and second segment in our third option. 276 277 00:12:01,750 --> 00:12:04,550 So this is a good shorthand that we can use 277 278 00:12:04,550 --> 00:12:07,200 and we identify that it was an IPv6 address 278 279 00:12:07,200 --> 00:12:08,900 because we removed all the zeros 279 280 00:12:08,900 --> 00:12:12,270 between the first and second segment inside this address. 280 281 00:12:12,270 --> 00:12:15,440 So if you count up something that looks like an IPv6 address 281 282 00:12:15,440 --> 00:12:19,210 and it has 12, exactly 12 hexadecimal digits 282 283 00:12:19,210 --> 00:12:20,720 separated by single colons 283 284 00:12:20,720 --> 00:12:22,590 and you don't see a double colon anywhere, 284 285 00:12:22,590 --> 00:12:25,860 that is a MAC address, not an IPv6 address. 285 286 00:12:25,860 --> 00:12:27,930 Otherwise if it looks something like this 286 287 00:12:27,930 --> 00:12:29,580 and includes hexadecimal digits, 287 288 00:12:29,580 --> 00:12:32,920 it's going to be an IPv6 address on exam day. 288 289 00:12:32,920 --> 00:12:35,210 For the exam, you just need to be able to recognize 289 290 00:12:35,210 --> 00:12:37,290 what an IPv6 address looks like 290 291 00:12:37,290 --> 00:12:39,500 and you should be able to summarize one down 291 292 00:12:39,500 --> 00:12:41,800 by taking out zeros and consolidating them 292 293 00:12:41,800 --> 00:12:43,720 using that double colon trick. 293 294 00:12:43,720 --> 00:12:46,080 If you can do these two things, you're going to be fine 294 295 00:12:46,080 --> 00:12:48,730 for IPv6 addressing on exam day. 295 296 00:12:48,730 --> 00:12:51,010 Now when it comes to IPv6 addressing, 296 297 00:12:51,010 --> 00:12:53,729 there are three different address types that you can use, 297 298 00:12:53,729 --> 00:12:56,260 unicast addresses, multicast addresses 298 299 00:12:56,260 --> 00:12:57,950 and anycast addresses. 299 300 00:12:57,950 --> 00:13:00,400 One of the interesting things about IPv6 300 301 00:13:00,400 --> 00:13:02,770 that really distinguishes it from IPv4 301 302 00:13:02,770 --> 00:13:05,570 is that we can assign multiple IPv6 addresses 302 303 00:13:05,570 --> 00:13:07,600 to a single interface on a client 303 304 00:13:07,600 --> 00:13:09,470 and these assignments can be a mixture 304 305 00:13:09,470 --> 00:13:11,410 of any of these three different types, 305 306 00:13:11,410 --> 00:13:14,020 unicast, multicast and anycast. 306 307 00:13:14,020 --> 00:13:16,870 So even if you only have one network interface card 307 308 00:13:16,870 --> 00:13:18,670 on your workstation or laptop, 308 309 00:13:18,670 --> 00:13:21,150 you could have multiple IPv6 addresses 309 310 00:13:21,150 --> 00:13:23,600 and different types of IPv6 addresses 310 311 00:13:23,600 --> 00:13:26,120 assigned to that one card. 311 312 00:13:26,120 --> 00:13:28,200 Unicast addresses are going to be used to identify 312 313 00:13:28,200 --> 00:13:29,700 a single interface. 313 314 00:13:29,700 --> 00:13:32,700 These are broken down into globally-routed unicast addresses 314 315 00:13:32,700 --> 00:13:34,670 and link-local addresses. 315 316 00:13:34,670 --> 00:13:36,490 A globally-routed unicast address 316 317 00:13:36,490 --> 00:13:39,900 is similar to what we have as a public address with IPv4 317 318 00:13:39,900 --> 00:13:43,340 using unicast A, B and C class addresses. 318 319 00:13:43,340 --> 00:13:46,590 Now in IPv6, a globally-routed unicast address 319 320 00:13:46,590 --> 00:13:49,310 is always going to start out with its first segment 320 321 00:13:49,310 --> 00:13:52,780 containing 2000 to 3999. 321 322 00:13:52,780 --> 00:13:56,490 Now if you see 2000 to 3999 as your first segment, 322 323 00:13:56,490 --> 00:13:59,500 this means it's a globally-routed unicast address. 323 324 00:13:59,500 --> 00:14:01,800 For example, the IPv6 address 324 325 00:14:01,800 --> 00:14:04,830 of 25A40DB885A3123456788A2E03707334 325 326 00:14:14,560 --> 00:14:17,740 would be globally-routable as a unicast address 326 327 00:14:17,740 --> 00:14:20,820 because its first segment contains 25A4 327 328 00:14:20,820 --> 00:14:24,420 which is between 2000 and 3099. 328 329 00:14:24,420 --> 00:14:26,410 Now a link-local address on the other hand, 329 330 00:14:26,410 --> 00:14:28,420 also called a local use address, 330 331 00:14:28,420 --> 00:14:31,780 is used like a private IP address was in IPv4. 331 332 00:14:31,780 --> 00:14:34,690 A link-local address in IPv6 can only be used 332 333 00:14:34,690 --> 00:14:37,590 on a local area network and it always is going to begin 333 334 00:14:37,590 --> 00:14:42,590 with FE80 as its first segment within an IPv6 address. 334 335 00:14:42,670 --> 00:14:45,500 Now whenever an IPv6 system starts up, 335 336 00:14:45,500 --> 00:14:47,830 it's going to actually create a link-local address 336 337 00:14:47,830 --> 00:14:50,810 for each IPv6 interface on that system 337 338 00:14:50,810 --> 00:14:52,460 even if a globally-routable address 338 339 00:14:52,460 --> 00:14:54,490 was already manually configured or obtained 339 340 00:14:54,490 --> 00:14:57,440 through a configuration protocol like DHCP. 340 341 00:14:57,440 --> 00:15:00,090 To do this, it's going to use something known as SLAAC, 341 342 00:15:00,090 --> 00:15:04,580 the Stateless Address Auto Configuration or SLAAC. 342 343 00:15:04,580 --> 00:15:06,340 With stateless auto configuration, 343 344 00:15:06,340 --> 00:15:08,420 the host does not need to obtain addresses 344 345 00:15:08,420 --> 00:15:09,930 or other configuration information 345 346 00:15:09,930 --> 00:15:12,610 from a centralized server like DHCP. 346 347 00:15:12,610 --> 00:15:15,380 Instead, it can actually independently assign itself 347 348 00:15:15,380 --> 00:15:17,750 a link-local address, test the uniqueness 348 349 00:15:17,750 --> 00:15:19,150 of that link-local address, 349 350 00:15:19,150 --> 00:15:21,150 assign the link-local address to itself, 350 351 00:15:21,150 --> 00:15:23,950 contact the router and provide direction to the node 351 352 00:15:23,950 --> 00:15:26,420 about how to proceed with the auto configuration 352 353 00:15:26,420 --> 00:15:29,500 and it can even configure the global unicast address 353 354 00:15:29,500 --> 00:15:30,840 that it wants to use. 354 355 00:15:30,840 --> 00:15:33,260 We're going to come back to this concept in just a few minutes 355 356 00:15:33,260 --> 00:15:35,670 as we dive a bit deeper into it as we start to talk 356 357 00:15:35,670 --> 00:15:39,330 about EUI-64 and the Neighbor Discovery Protocol 357 358 00:15:39,330 --> 00:15:40,950 since both of these processes 358 359 00:15:40,950 --> 00:15:43,190 are used with the stateless address auto configuration 359 360 00:15:43,190 --> 00:15:45,310 protocol known as SLAAC. 360 361 00:15:45,310 --> 00:15:47,440 Next we have multicast addresses. 361 362 00:15:47,440 --> 00:15:49,580 Now multicast addresses are used to identify 362 363 00:15:49,580 --> 00:15:52,030 a group of interfaces so that a packet can be sent 363 364 00:15:52,030 --> 00:15:54,240 to a multicast address and then be delivered 364 365 00:15:54,240 --> 00:15:56,410 to all the interfaces within a group. 365 366 00:15:56,410 --> 00:15:59,960 In IPv6, a multicast address will always contain FF 366 367 00:15:59,960 --> 00:16:03,200 as the first two digits within the first segment. 367 368 00:16:03,200 --> 00:16:06,020 If you see FF at the beginning of an IPv6 address, 368 369 00:16:06,020 --> 00:16:08,540 remember, it's multicast. 369 370 00:16:08,540 --> 00:16:10,070 The final type of address we have 370 371 00:16:10,070 --> 00:16:12,470 is known as an anycast address. 371 372 00:16:12,470 --> 00:16:15,360 Anycast addresses are used to identify a set of interfaces 372 373 00:16:15,360 --> 00:16:18,130 so that a packet can be sent to any member of a set. 373 374 00:16:18,130 --> 00:16:20,060 We're going to talk more about how anycast works 374 375 00:16:20,060 --> 00:16:23,330 when we cover IPv6 data flows in a separate video. 375 376 00:16:23,330 --> 00:16:25,020 Anycast addresses are actually allocated 376 377 00:16:25,020 --> 00:16:26,760 from the unicast address space 377 378 00:16:26,760 --> 00:16:29,740 so there's really no way to determine if an IPv6 address 378 379 00:16:29,740 --> 00:16:34,120 is unicast or anycast just by looking at the IPv6 address. 379 380 00:16:34,120 --> 00:16:36,740 Now when you're looking at multicast or link-local, 380 381 00:16:36,740 --> 00:16:38,490 you have a very easy way to do this, 381 382 00:16:38,490 --> 00:16:40,100 but you don't have an easy way 382 383 00:16:40,100 --> 00:16:42,580 to figure out unicast versus anycast. 383 384 00:16:42,580 --> 00:16:44,810 Alright, let's go back and talk a little bit more 384 385 00:16:44,810 --> 00:16:45,690 about SLAAC, 385 386 00:16:45,690 --> 00:16:48,840 the stateless address auto configuration process. 386 387 00:16:48,840 --> 00:16:50,810 Now as I said, in IPv6, 387 388 00:16:50,810 --> 00:16:53,710 there is an auto configuration process known as SLAAC 388 389 00:16:53,710 --> 00:16:55,680 and we use this to discover the current network 389 390 00:16:55,680 --> 00:16:57,200 that the interface is located on 390 391 00:16:57,200 --> 00:17:00,060 and then allow it to select its own host ID 391 392 00:17:00,060 --> 00:17:05,060 based on its MAC address using a process known as EUI-64. 392 393 00:17:05,260 --> 00:17:10,120 Now this EUI-64 or Extended Unique Identifier process 393 394 00:17:10,120 --> 00:17:13,330 will allow a host to assign itself a unique 64-bit 394 395 00:17:13,330 --> 00:17:17,950 IPv6 interface identifier called EUI-64. 395 396 00:17:17,950 --> 00:17:20,720 Now this EUI-64 format address 396 397 00:17:20,720 --> 00:17:24,180 is obtained by using the interface's 48-bit MAC address. 397 398 00:17:24,180 --> 00:17:27,960 The MAC address is first separated into two 24-bit portions. 398 399 00:17:27,960 --> 00:17:30,100 The first half of the MAC address is going to contain 399 400 00:17:30,100 --> 00:17:33,800 the OUI or the Organizational Unique Identifier 400 401 00:17:33,800 --> 00:17:35,560 and the second half is going to contain 401 402 00:17:35,560 --> 00:17:37,710 the specific network interface card. 402 403 00:17:37,710 --> 00:17:41,100 Now in between those, we're going to shove a 16-bit 403 404 00:17:41,100 --> 00:17:44,440 hexadecimal value of FFFE. 404 405 00:17:44,440 --> 00:17:48,670 This way I can take 24 bits, 16 bits and 24 bits 405 406 00:17:48,670 --> 00:17:53,470 and put together to get a 64-bit EUI address. 406 407 00:17:53,470 --> 00:17:56,050 Now this gives you the 64 bits that you're going to need 407 408 00:17:56,050 --> 00:17:58,570 to identify your interface on that network. 408 409 00:17:58,570 --> 00:18:01,000 Then the interface will use auto discovery 409 410 00:18:01,000 --> 00:18:02,550 to determine the network it is on 410 411 00:18:02,550 --> 00:18:05,750 and add the network portion of the IPv6 address 411 412 00:18:05,750 --> 00:18:07,930 which is going to be the first 64 bits 412 413 00:18:07,930 --> 00:18:09,670 inside of our addresses. 413 414 00:18:09,670 --> 00:18:11,670 Now we're going to put that first 64 bits 414 415 00:18:11,670 --> 00:18:14,250 to represent the network in front of the 64 bits 415 416 00:18:14,250 --> 00:18:18,110 from the EUI-64 address we created from our MAC address 416 417 00:18:18,110 --> 00:18:21,750 to create a unicast globally-routable IPv6 address 417 418 00:18:21,750 --> 00:18:23,270 that we can now use. 418 419 00:18:23,270 --> 00:18:25,620 So you can see how all this works together 419 420 00:18:25,620 --> 00:18:26,880 using that MAC address 420 421 00:18:26,880 --> 00:18:29,400 to create this globally-routable address. 421 422 00:18:29,400 --> 00:18:32,910 Now DHCP can also be used within IPv6 422 423 00:18:32,910 --> 00:18:34,280 if you prefer to use it. 423 424 00:18:34,280 --> 00:18:35,670 If you do, you're going to have to use 424 425 00:18:35,670 --> 00:18:38,220 the DHCP version six protocol. 425 426 00:18:38,220 --> 00:18:39,670 This would allow you to have DHCP 426 427 00:18:39,670 --> 00:18:43,370 automatically assign things from a DHCP version six server. 427 428 00:18:43,370 --> 00:18:47,200 But since the auto configuration process with EUI-64 428 429 00:18:47,200 --> 00:18:50,120 is already built into the IPv6 protocol by default, 429 430 00:18:50,120 --> 00:18:52,980 you really don't need to use DHCP version six. 430 431 00:18:52,980 --> 00:18:55,680 But if you do want to use DHCP version six, 431 432 00:18:55,680 --> 00:18:57,560 you can and it will allow you to assign 432 433 00:18:57,560 --> 00:19:00,070 what addresses each interface is going to get 433 434 00:19:00,070 --> 00:19:00,903 instead of allowing them 434 435 00:19:00,903 --> 00:19:03,870 to use the auto configuration protocol of SLAAC. 435 436 00:19:03,870 --> 00:19:07,270 Now as I said, IPv6 will choose its own address 436 437 00:19:07,270 --> 00:19:09,640 based on its MAC address by default. 437 438 00:19:09,640 --> 00:19:12,160 Then it's going to use this thing known as NDP 438 439 00:19:12,160 --> 00:19:14,040 or the Neighbor Discovery Protocol 439 440 00:19:14,040 --> 00:19:17,080 to learn about the other layer two addresses on the network 440 441 00:19:17,080 --> 00:19:18,710 based on their MAC addresses 441 442 00:19:18,710 --> 00:19:21,340 and then it will pick its own host ID. 442 443 00:19:21,340 --> 00:19:23,310 Let's talk a little bit more about NDP, 443 444 00:19:23,310 --> 00:19:25,220 that Neighbor Discovery Protocol. 444 445 00:19:25,220 --> 00:19:27,570 NDP is used to perform router solicitation, 445 446 00:19:27,570 --> 00:19:30,080 router advertisement, neighbor solicitation, 446 447 00:19:30,080 --> 00:19:32,580 neighbor advertisement and redirection. 447 448 00:19:32,580 --> 00:19:34,270 Router solicitation is when your client 448 449 00:19:34,270 --> 00:19:35,390 is going to send a message 449 450 00:19:35,390 --> 00:19:37,230 to locate the routers on its network 450 451 00:19:37,230 --> 00:19:39,510 because it has to figure out what the default gateway is 451 452 00:19:39,510 --> 00:19:41,820 that everyone's using so it can get out of that network 452 453 00:19:41,820 --> 00:19:43,220 and onto the internet. 453 454 00:19:43,220 --> 00:19:46,150 Routers can also do advertisements over NDP. 454 455 00:19:46,150 --> 00:19:46,990 Essentially they're going to say, 455 456 00:19:46,990 --> 00:19:48,820 hey, I'm the router, I'm over here. 456 457 00:19:48,820 --> 00:19:51,640 You guys can solicit me and ask me questions. 457 458 00:19:51,640 --> 00:19:54,050 Neighbor solicitation is where your IPv6 458 459 00:19:54,050 --> 00:19:55,120 starts going around and saying, 459 460 00:19:55,120 --> 00:19:57,080 hey, what other nodes are on this network 460 461 00:19:57,080 --> 00:19:59,530 and they ask their neighbors or other devices. 461 462 00:19:59,530 --> 00:20:01,720 This allows your interface to try to determine 462 463 00:20:01,720 --> 00:20:04,160 what link layer addresses or layer two addresses 463 464 00:20:04,160 --> 00:20:06,210 are out there so it can learn from them 464 465 00:20:06,210 --> 00:20:08,550 and figure out how to talk to them directly. 465 466 00:20:08,550 --> 00:20:11,480 Now neighbor advertisement is like router advertisement, 466 467 00:20:11,480 --> 00:20:13,260 but it happens with your neighbors. 467 468 00:20:13,260 --> 00:20:15,620 Those clients start saying, hey, hey, I'm over here. 468 469 00:20:15,620 --> 00:20:17,260 These are all the different services that I offer. 469 470 00:20:17,260 --> 00:20:18,880 You should come talk to me. 470 471 00:20:18,880 --> 00:20:20,510 Finally, we have redirection 471 472 00:20:20,510 --> 00:20:22,290 which is where routers can inform the hosts 472 473 00:20:22,290 --> 00:20:24,620 that there are better first-hop router options out there 473 474 00:20:24,620 --> 00:20:26,760 to increase the efficiencies of your network. 474 475 00:20:26,760 --> 00:20:29,230 For example, if I'm sitting in San Juan, Puerto Rico 475 476 00:20:29,230 --> 00:20:31,860 and my computer thinks the best first-hop router 476 477 00:20:31,860 --> 00:20:34,420 is for me to get to New York and then go over to California, 477 478 00:20:34,420 --> 00:20:36,560 this may not be the most efficient route for me, 478 479 00:20:36,560 --> 00:20:37,950 but it probably works. 479 480 00:20:37,950 --> 00:20:40,380 Now another router in Florida might go, hey, you know what? 480 481 00:20:40,380 --> 00:20:42,360 I'm actually a better first-hop router for you. 481 482 00:20:42,360 --> 00:20:44,610 I can save you some time. So I'm closer. 482 483 00:20:44,610 --> 00:20:46,840 Come talk to me and I'll send your information 483 484 00:20:46,840 --> 00:20:48,740 all the way over to California faster for you 484 485 00:20:48,740 --> 00:20:50,350 than that guy up in New York can. 485 486 00:20:50,350 --> 00:20:52,370 This is the idea of redirection. 486 487 00:20:52,370 --> 00:20:54,640 Essentially the router says I'm better and faster. 487 488 00:20:54,640 --> 00:20:56,060 Use me instead. 488 489 00:20:56,060 --> 00:20:59,070 Now for the exam, you don't need to know NDP in depth, 489 490 00:20:59,070 --> 00:21:01,290 but you should understand that NDP, 490 491 00:21:01,290 --> 00:21:02,960 this Neighbor Discovery Protocol, 491 492 00:21:02,960 --> 00:21:05,850 is used in IPv6 and it takes a lot of the functions 492 493 00:21:05,850 --> 00:21:08,310 from layer two and layer three of the OSI model 493 494 00:21:08,310 --> 00:21:10,380 for router advertisement and neighbor discovery 494 495 00:21:10,380 --> 00:21:11,630 and handles them for you.