1 00:00:00,770 --> 00:00:02,560 Network redundancy. 2 00:00:02,560 --> 00:00:05,050 Network redundancy is focused on ensuring our network 3 00:00:05,050 --> 00:00:07,390 remains up and running at all times 4 00:00:07,390 --> 00:00:09,150 to increase it's availability. 5 00:00:09,150 --> 00:00:10,540 This includes the servers connections 6 00:00:10,540 --> 00:00:12,630 to the network, the connections between our switches 7 00:00:12,630 --> 00:00:15,320 and our routers, and our connections to the internet. 8 00:00:15,320 --> 00:00:16,300 To accomplish this, 9 00:00:16,300 --> 00:00:18,240 our servers often have two or more 10 00:00:18,240 --> 00:00:19,350 network interface parts, 11 00:00:19,350 --> 00:00:21,100 and they can be operated as a pair 12 00:00:21,100 --> 00:00:23,430 or in a low balancing configuration. 13 00:00:23,430 --> 00:00:24,290 In this example, 14 00:00:24,290 --> 00:00:26,409 I have a network with five network cards installed. 15 00:00:26,409 --> 00:00:28,700 You can see that there's currently four network cables 16 00:00:28,700 --> 00:00:30,130 currently plugged into it. 17 00:00:30,130 --> 00:00:32,270 This way, if one of those cards fails, 18 00:00:32,270 --> 00:00:33,830 the other ones can take over the load 19 00:00:33,830 --> 00:00:35,040 and the demand. 20 00:00:35,040 --> 00:00:37,030 Now this can paired for redundancy, 21 00:00:37,030 --> 00:00:38,050 or you can split them 22 00:00:38,050 --> 00:00:39,430 and put them into two groups 23 00:00:39,430 --> 00:00:41,180 so you can have additional throughput 24 00:00:41,180 --> 00:00:44,640 by operating more than one at a time simultaneously. 25 00:00:44,640 --> 00:00:47,100 In this example I might create two groups, 26 00:00:47,100 --> 00:00:48,570 one with four network cards in it 27 00:00:48,570 --> 00:00:51,150 and one with a single network card by itself. 28 00:00:51,150 --> 00:00:52,910 That gives me the total of five. 29 00:00:52,910 --> 00:00:55,890 Four network cards can operate in a shared load capacity, 30 00:00:55,890 --> 00:00:57,670 meaning that all four will work together. 31 00:00:57,670 --> 00:01:00,120 So if they were each 100 megabytes per second each, 32 00:01:00,120 --> 00:01:01,380 that gives me a combined 33 00:01:01,380 --> 00:01:03,110 400 megabytes per second, 34 00:01:03,110 --> 00:01:05,300 but that fifth one is sitting there by itself 35 00:01:05,300 --> 00:01:07,800 and it has 100 megabytes per second to use. 36 00:01:07,800 --> 00:01:10,000 We use that as our backup redundancy. 37 00:01:10,000 --> 00:01:11,530 So if those four went out, 38 00:01:11,530 --> 00:01:13,220 that fifth one could take over, 39 00:01:13,220 --> 00:01:15,330 even though it's a slower conenction. 40 00:01:15,330 --> 00:01:17,860 Now to ensure our network devices have redundancy 41 00:01:17,860 --> 00:01:19,650 we often use switches or routers 42 00:01:19,650 --> 00:01:21,030 that are configured with multiple 43 00:01:21,030 --> 00:01:23,660 and redundant network cables going up between them. 44 00:01:23,660 --> 00:01:25,380 For example, I have a switch here with 45 00:01:25,380 --> 00:01:27,854 two trunk ports using fiberoptic cables. 46 00:01:27,854 --> 00:01:30,540 This allows me to have that switch be able 47 00:01:30,540 --> 00:01:32,830 to get service from two separate routers. 48 00:01:32,830 --> 00:01:34,193 And so if one router goes down 49 00:01:34,193 --> 00:01:37,150 the other router can take over as the secondary 50 00:01:37,150 --> 00:01:39,010 and then carry all the data from that switch 51 00:01:39,010 --> 00:01:40,210 out to the network. 52 00:01:40,210 --> 00:01:42,180 This gives me redundancy by allowing 53 00:01:42,180 --> 00:01:43,540 us to have different pathways 54 00:01:43,540 --> 00:01:45,000 out for that switch. 55 00:01:45,000 --> 00:01:46,470 So, as you can see, when you're planning 56 00:01:46,470 --> 00:01:47,630 for network redundancy 57 00:01:47,630 --> 00:01:49,680 you need to think about it in three parts. 58 00:01:49,680 --> 00:01:51,240 You need to think about it as the device, 59 00:01:51,240 --> 00:01:53,364 those network interface cards and those cables. 60 00:01:53,364 --> 00:01:54,790 You also need to think about it from the 61 00:01:54,790 --> 00:01:56,360 switches and routers perspective 62 00:01:56,360 --> 00:01:58,930 to make sure you have redundant paths inside the network. 63 00:01:58,930 --> 00:02:01,350 And you need to think about it from the internet connection. 64 00:02:01,350 --> 00:02:02,183 And making sure you have 65 00:02:02,183 --> 00:02:04,163 redundant paths out for that as well.