1 1 00:00:00,910 --> 00:00:03,050 We spent a lot of time in the last lesson, 2 2 00:00:03,050 --> 00:00:06,170 talking about the different physical and logical topologies. 3 3 00:00:06,170 --> 00:00:07,760 Now all of those logical ones 4 4 00:00:07,760 --> 00:00:10,060 are still going to apply to our wireless networks. 5 5 00:00:10,060 --> 00:00:12,510 But when we talk about it from a physical perspective, 6 6 00:00:12,510 --> 00:00:14,560 wireless does add two different modes 7 7 00:00:14,560 --> 00:00:16,060 that we need to understand. 8 8 00:00:16,060 --> 00:00:17,540 So when we look at the first one, 9 9 00:00:17,540 --> 00:00:19,610 this is called Infrastructure Mode. 10 10 00:00:19,610 --> 00:00:21,540 Infrastructure Mode is the most common type 11 11 00:00:21,540 --> 00:00:22,690 of wireless network. 12 12 00:00:22,690 --> 00:00:24,300 In fact, it's probably the one you're using 13 13 00:00:24,300 --> 00:00:25,770 to watch this video. 14 14 00:00:25,770 --> 00:00:28,330 If you're sitting at home, you have wireless in your house 15 15 00:00:28,330 --> 00:00:29,860 and it connects to an outside provider 16 16 00:00:29,860 --> 00:00:31,820 through your cable or your fiber modem. 17 17 00:00:31,820 --> 00:00:33,780 This is Infrastructure Mode. 18 18 00:00:33,780 --> 00:00:35,410 You have a centrally managed device, 19 19 00:00:35,410 --> 00:00:36,770 your wireless access point, 20 20 00:00:36,770 --> 00:00:39,800 and that you've given it a name, probably a password. 21 21 00:00:39,800 --> 00:00:42,020 And you use that as you would a star topology 22 22 00:00:42,020 --> 00:00:45,410 in a physical network, but you're doing it wirelessly. 23 23 00:00:45,410 --> 00:00:47,830 Now this is going to support wireless security controls 24 24 00:00:47,830 --> 00:00:49,810 and other benefits that you just don't get 25 25 00:00:49,810 --> 00:00:53,110 when you go to our second mode, which is known as Ad Hoc. 26 26 00:00:53,110 --> 00:00:55,310 Now Ad Hoc is decentralized. 27 27 00:00:55,310 --> 00:00:57,560 It operates like a peer-to-peer network does, 28 28 00:00:57,560 --> 00:00:59,890 there's no routers, there's no access points. 29 29 00:00:59,890 --> 00:01:02,670 Instead, I connect my laptop to your laptop 30 30 00:01:02,670 --> 00:01:04,890 and we can make those routing decisions on the fly 31 31 00:01:04,890 --> 00:01:06,560 and make them dynamically. 32 32 00:01:06,560 --> 00:01:08,430 This can allow people to jump in and jump out 33 33 00:01:08,430 --> 00:01:10,260 of the network as much as they want. 34 34 00:01:10,260 --> 00:01:12,000 It's almost like the old school chat rooms 35 35 00:01:12,000 --> 00:01:14,260 we used to have on AOL or CompuServe, right? 36 36 00:01:14,260 --> 00:01:16,670 People would come in, they'd talk and then they'd leave. 37 37 00:01:16,670 --> 00:01:18,920 And they would just come in and out all the time. 38 38 00:01:18,920 --> 00:01:20,970 Well, that's how this wireless network would work 39 39 00:01:20,970 --> 00:01:23,010 when you're dealing with Ad Hoc mode. 40 40 00:01:23,010 --> 00:01:24,770 Now there is a third type that we have, 41 41 00:01:24,770 --> 00:01:26,900 which is called a Wireless Mesh. 42 42 00:01:26,900 --> 00:01:28,230 And you might think, oh, well, 43 43 00:01:28,230 --> 00:01:30,550 that's just going to be a combination of the other two. 44 44 00:01:30,550 --> 00:01:32,220 Well, not really. 45 45 00:01:32,220 --> 00:01:34,650 A Wireless Mesh is actually completely different. 46 46 00:01:34,650 --> 00:01:37,320 A Wireless Mesh is an interconnection of different types 47 47 00:01:37,320 --> 00:01:41,530 of nodes, devices, and radios to create this mesh topology. 48 48 00:01:41,530 --> 00:01:43,930 So if we're going to have different routers and gateways 49 49 00:01:43,930 --> 00:01:46,150 and clients and servers and radio antennas, 50 50 00:01:46,150 --> 00:01:47,590 we're going to mesh them all together 51 51 00:01:47,590 --> 00:01:49,350 and create this unique network. 52 52 00:01:49,350 --> 00:01:51,030 So we can use different radio frequencies 53 53 00:01:51,030 --> 00:01:53,240 like Bluetooth and WiFi and microwave 54 54 00:01:53,240 --> 00:01:54,700 and cellular and satellite. 55 55 00:01:54,700 --> 00:01:56,170 And all of them can combine 56 56 00:01:56,170 --> 00:01:58,160 into this single wireless network 57 57 00:01:58,160 --> 00:02:00,430 so that we can expand our network access. 58 58 00:02:00,430 --> 00:02:02,510 This gives us redundant and reliable connections 59 59 00:02:02,510 --> 00:02:05,410 as we move forward, especially in harsh environments. 60 60 00:02:05,410 --> 00:02:08,430 So where might we use a Wireless Mesh topology? 61 61 00:02:08,430 --> 00:02:10,020 Well, after there's a hurricane 62 62 00:02:10,020 --> 00:02:12,060 or another disaster related event, 63 63 00:02:12,060 --> 00:02:14,250 people may come in to do humanitarian assistance 64 64 00:02:14,250 --> 00:02:15,083 in the area. 65 65 00:02:15,083 --> 00:02:16,370 And when they come, they're going to bring 66 66 00:02:16,370 --> 00:02:17,910 their networks with them because they need a way 67 67 00:02:17,910 --> 00:02:20,420 to communicate back to where they came from. 68 68 00:02:20,420 --> 00:02:22,160 So some of them will communicate over cellular, 69 69 00:02:22,160 --> 00:02:23,800 if the cellular network still works, 70 70 00:02:23,800 --> 00:02:26,100 some over wireless that they bring in and set up, 71 71 00:02:26,100 --> 00:02:28,710 some over satellite, some over microwave, 72 72 00:02:28,710 --> 00:02:30,260 some over a landline. 73 73 00:02:30,260 --> 00:02:31,700 But even if you had a landline, 74 74 00:02:31,700 --> 00:02:34,250 it may not be reliable because there was a disaster there. 75 75 00:02:34,250 --> 00:02:36,900 And so they might back that up using a wireless signal 76 76 00:02:36,900 --> 00:02:39,130 or a satellite or a cellular modem. 77 77 00:02:39,130 --> 00:02:41,190 Now, as we have all these different connections 78 78 00:02:41,190 --> 00:02:44,220 working together, this gives us our mesh topology. 79 79 00:02:44,220 --> 00:02:47,340 So maybe we set up a base camp that has WiFi in it 80 80 00:02:47,340 --> 00:02:48,620 for everybody to access, 81 81 00:02:48,620 --> 00:02:50,730 but then we have it connecting to another base camp 82 82 00:02:50,730 --> 00:02:52,010 over a microwave link. 83 83 00:02:52,010 --> 00:02:54,100 And then we have that connecting back over satellite, 84 84 00:02:54,100 --> 00:02:55,720 back to their home country. 85 85 00:02:55,720 --> 00:02:58,530 This is the idea of using this wireless mesh network. 86 86 00:02:58,530 --> 00:03:00,540 We're combining these two or three or four 87 87 00:03:00,540 --> 00:03:02,760 different technologies to create a mesh network 88 88 00:03:02,760 --> 00:03:04,500 that can be used by anyone. 89 89 00:03:04,500 --> 00:03:07,300 Now, as we keep expanding our networks over a large area, 90 90 00:03:07,300 --> 00:03:08,990 by combining things with microwave 91 91 00:03:08,990 --> 00:03:11,130 and satellite and cellular, 92 92 00:03:11,130 --> 00:03:12,990 this is going to allow us to be able to have 93 93 00:03:12,990 --> 00:03:14,790 all this stuff working together well. 94 94 00:03:14,790 --> 00:03:16,990 Because if we have WiFi that can only go maybe 95 95 00:03:16,990 --> 00:03:18,660 100 or 200 feet, right? 96 96 00:03:18,660 --> 00:03:21,660 But a microwave link can go 30 or 40 miles 97 97 00:03:21,660 --> 00:03:24,860 and satellite can go 100s or 1,000s of miles. 98 98 00:03:24,860 --> 00:03:27,570 And so this is the idea here, as we create this mesh, 99 99 00:03:27,570 --> 00:03:29,430 we can keep expanding our access. 100 100 00:03:29,430 --> 00:03:30,980 As you can see here in the diagram 101 101 00:03:30,980 --> 00:03:32,130 where we're going to be using satellite 102 102 00:03:32,130 --> 00:03:35,640 to go for 1,000s of miles, microwaves to go 10s of miles 103 103 00:03:35,640 --> 00:03:37,240 and then wireless, which goes, you know, 104 104 00:03:37,240 --> 00:03:39,350 maybe 10s of feet or 100s of feet. 105 105 00:03:39,350 --> 00:03:41,240 And we can pull all of this together to create this 106 106 00:03:41,240 --> 00:03:44,160 great, reliable, redundant network that we can use 107 107 00:03:44,160 --> 00:03:47,200 during a disaster or humanitarian assistance type mission. 108 108 00:03:47,200 --> 00:03:48,340 That's the idea. 109 109 00:03:48,340 --> 00:03:51,560 So as we talk about typologies specific to wireless, 110 110 00:03:51,560 --> 00:03:53,230 I want you to remember the three types, 111 111 00:03:53,230 --> 00:03:56,433 Infrastructure, Ad Hoc, and Mesh Topology.