1 00:00:00,540 --> 00:00:03,690 We first talked about data flows back in IPv4 2 00:00:03,690 --> 00:00:05,070 earlier in this section, 3 00:00:05,070 --> 00:00:08,070 but they changed a little bit here in IPv6. 4 00:00:08,070 --> 00:00:09,780 Now there's still three data flows, 5 00:00:09,780 --> 00:00:11,460 but one of them has changed. 6 00:00:11,460 --> 00:00:12,660 We still have unicast, 7 00:00:12,660 --> 00:00:14,130 we still have multicast, 8 00:00:14,130 --> 00:00:16,290 but now we've done away with broadcast 9 00:00:16,290 --> 00:00:19,320 and we've introduced something called Anycast instead. 10 00:00:19,320 --> 00:00:22,470 Now, unicast works just like it did in IPv4, 11 00:00:22,470 --> 00:00:24,600 but instead of using IPv4 addresses, 12 00:00:24,600 --> 00:00:27,000 we're going to use IPv6 addresses. 13 00:00:27,000 --> 00:00:28,830 Now in this case, let's say my server wants 14 00:00:28,830 --> 00:00:31,680 to send a message to both PC one and PC two. 15 00:00:31,680 --> 00:00:33,570 Well, it's going to have to send out two copies 16 00:00:33,570 --> 00:00:36,330 of the same message, one intended for each host 17 00:00:36,330 --> 00:00:38,670 because it's going from one server to one host, 18 00:00:38,670 --> 00:00:41,400 and back from one server to the other host. 19 00:00:41,400 --> 00:00:44,250 Notice the only difference here is their IP addresses. 20 00:00:44,250 --> 00:00:47,040 We're using A, B, C, D, colon colon one, 21 00:00:47,040 --> 00:00:49,560 and all this space in between those two colons 22 00:00:49,560 --> 00:00:50,850 will be filled up with zeros 23 00:00:50,850 --> 00:00:53,880 to get us back to 32 hexa decimal digits. 24 00:00:53,880 --> 00:00:55,350 Next we have multicast. 25 00:00:55,350 --> 00:00:57,990 And in multicast, just like IPv4, 26 00:00:57,990 --> 00:00:59,910 we use multicast groups. 27 00:00:59,910 --> 00:01:01,410 The server's going to address the message 28 00:01:01,410 --> 00:01:02,820 to the multicast group. 29 00:01:02,820 --> 00:01:05,910 In this case FF zero zero colon colon A. 30 00:01:05,910 --> 00:01:07,320 Remember, anything that starts 31 00:01:07,320 --> 00:01:09,690 with FF is a multicast address, 32 00:01:09,690 --> 00:01:11,460 and then it's going to get to the switch. 33 00:01:11,460 --> 00:01:12,750 And when it gets to the switch, 34 00:01:12,750 --> 00:01:14,940 it distributes the additional copies to each 35 00:01:14,940 --> 00:01:17,280 of the recipients in the multicast group number 36 00:01:17,280 --> 00:01:20,040 based on this number one that we're using. 37 00:01:20,040 --> 00:01:22,830 Data is going to travel from a single source, our server 38 00:01:22,830 --> 00:01:25,920 to multiple but specific destination devices. 39 00:01:25,920 --> 00:01:28,620 The third type of data flow we have is known as anycast. 40 00:01:28,620 --> 00:01:31,440 And this is the different one from IPv4. 41 00:01:31,440 --> 00:01:33,660 This is the one that's unique to IPv6 42 00:01:33,660 --> 00:01:36,660 because we did away with broadcast in IPv4. 43 00:01:36,660 --> 00:01:37,950 Now any cast is designed 44 00:01:37,950 --> 00:01:40,410 to let one host initiate an efficient updating 45 00:01:40,410 --> 00:01:43,200 of router tables for a group of other hosts. 46 00:01:43,200 --> 00:01:46,020 IPV six is able to determine which gateway the host 47 00:01:46,020 --> 00:01:48,930 is closest to and send the packets to that gateway 48 00:01:48,930 --> 00:01:51,480 as though it was a unicast communication. 49 00:01:51,480 --> 00:01:54,821 The gateway is then going to broadcast that through the anycast 50 00:01:54,821 --> 00:01:56,940 to any other host in the group until all 51 00:01:56,940 --> 00:01:58,710 of the routing tables are updated. 52 00:01:58,710 --> 00:02:00,390 Now what does this really look like? 53 00:02:00,390 --> 00:02:02,700 Well, let's take a look at this diagram on the screen. 54 00:02:02,700 --> 00:02:05,430 Here we have a server, and the router there is gone left, 55 00:02:05,430 --> 00:02:07,710 is going to send things out through anycast, 56 00:02:07,710 --> 00:02:09,900 it sends it out to the internet, and it's going to go 57 00:02:09,900 --> 00:02:12,690 to whatever the closest place is that has a router. 58 00:02:12,690 --> 00:02:14,160 Now, in this case, it's the router 59 00:02:14,160 --> 00:02:16,050 that's at the top of the screen here. 60 00:02:16,050 --> 00:02:18,510 Now once it gets to that router on top, it's then going to go 61 00:02:18,510 --> 00:02:20,850 to the DNS server and it'll reroute down 62 00:02:20,850 --> 00:02:22,560 through the routers onto the bottom 63 00:02:22,560 --> 00:02:23,940 and keep pushing that around, 64 00:02:23,940 --> 00:02:25,470 but the original router on the left side 65 00:02:25,470 --> 00:02:28,500 of the screen only had to send out that message once, 66 00:02:28,500 --> 00:02:29,460 and then from there, 67 00:02:29,460 --> 00:02:32,010 all of the other routers will figure out the best way 68 00:02:32,010 --> 00:02:34,170 to update everybody else's tables. 69 00:02:34,170 --> 00:02:36,630 That's the benefit of using something like anycast 70 00:02:36,630 --> 00:02:39,210 as opposed to using another way to update your routers. 71 00:02:39,210 --> 00:02:40,950 And this becomes very efficient 72 00:02:40,950 --> 00:02:43,353 and it's one of the benefits of using IPv6.