1 00:00:00,000 --> 00:00:00,960 In this lesson, 2 00:00:00,960 --> 00:00:03,840 we're going to discuss some high availability approaches. 3 00:00:03,840 --> 00:00:05,880 Now, it's essential to achieve high availability 4 00:00:05,880 --> 00:00:07,200 in your network environments 5 00:00:07,200 --> 00:00:09,179 if you want to be able to maintain continuous operations 6 00:00:09,179 --> 00:00:12,150 with minimal downtime for your end users. 7 00:00:12,150 --> 00:00:14,490 Network redundancy is focused on ensuring our networks 8 00:00:14,490 --> 00:00:16,347 remain up and running at all times 9 00:00:16,347 --> 00:00:18,660 so that we can increase our availability. 10 00:00:18,660 --> 00:00:20,790 This includes the server connections to the network, 11 00:00:20,790 --> 00:00:22,800 the connections between our switches and our routers 12 00:00:22,800 --> 00:00:24,720 and our connections out to the internet. 13 00:00:24,720 --> 00:00:25,890 To accomplish all of this, 14 00:00:25,890 --> 00:00:28,680 our servers have two or more network interface parts, 15 00:00:28,680 --> 00:00:30,180 and they can be operated as a pair 16 00:00:30,180 --> 00:00:32,580 or in a load balancing configuration. 17 00:00:32,580 --> 00:00:34,890 For example, I can have a network attached server 18 00:00:34,890 --> 00:00:36,840 with five network cards installed. 19 00:00:36,840 --> 00:00:37,870 On this particular server, 20 00:00:37,870 --> 00:00:40,380 I have four network cables plugged into it, 21 00:00:40,380 --> 00:00:42,210 and it's already providing services. 22 00:00:42,210 --> 00:00:44,631 Now under this configuration, if one of those cards fails, 23 00:00:44,631 --> 00:00:47,610 the other ones can take over the load and the demand. 24 00:00:47,610 --> 00:00:49,890 Now, these network cards can also be used in pairs 25 00:00:49,890 --> 00:00:50,970 for more redundancy, 26 00:00:50,970 --> 00:00:53,580 or we can split them up and put them into two groups 27 00:00:53,580 --> 00:00:54,750 so you have additional throughput 28 00:00:54,750 --> 00:00:57,240 by operating more of these cards at one time 29 00:00:57,240 --> 00:00:59,010 in a simultaneous manner. 30 00:00:59,010 --> 00:01:00,783 So let's say I create two groups, 31 00:01:00,783 --> 00:01:02,550 one with four network cards in it, 32 00:01:02,550 --> 00:01:05,610 and one with a single network card over there by itself. 33 00:01:05,610 --> 00:01:06,690 Now this will give me a total 34 00:01:06,690 --> 00:01:09,270 of five different network connections that we can have. 35 00:01:09,270 --> 00:01:11,970 Four of those can operate in a shared load capacity, 36 00:01:11,970 --> 00:01:13,020 and this means that all four 37 00:01:13,020 --> 00:01:15,600 will work together as one virtual card. 38 00:01:15,600 --> 00:01:18,810 So if each one is 100 megabits per second each, 39 00:01:18,810 --> 00:01:20,340 this will give me a combined amount 40 00:01:20,340 --> 00:01:22,410 of 400 megabits per second, 41 00:01:22,410 --> 00:01:24,210 and that fifth one sitting over there by itself, 42 00:01:24,210 --> 00:01:26,970 it will still be 100 megabits per second by itself, 43 00:01:26,970 --> 00:01:28,890 and we can use that as a backup connection 44 00:01:28,890 --> 00:01:31,530 for increased levels of redundancy if we need to. 45 00:01:31,530 --> 00:01:33,814 Now, if the group of four connections happens to go offline, 46 00:01:33,814 --> 00:01:36,018 that fifth one sitting by itself can take over 47 00:01:36,018 --> 00:01:37,950 and provide some level of service, 48 00:01:37,950 --> 00:01:40,410 even though it's going to be a slower connection. 49 00:01:40,410 --> 00:01:42,546 Now, in order to ensure our network devices have redundancy, 50 00:01:42,546 --> 00:01:44,550 we're also going to use things like switches 51 00:01:44,550 --> 00:01:45,780 and routers that are configured 52 00:01:45,780 --> 00:01:47,490 with multiple and redundant network cables 53 00:01:47,490 --> 00:01:48,810 going between them. 54 00:01:48,810 --> 00:01:50,370 For example, if I have a switch 55 00:01:50,370 --> 00:01:52,740 with two trunk ports using fiber optic cables, 56 00:01:52,740 --> 00:01:54,180 this can allow me to have that switch 57 00:01:54,180 --> 00:01:56,640 to be able to get service from two separate routers. 58 00:01:56,640 --> 00:01:58,591 And this way, if one of the routers goes down, 59 00:01:58,591 --> 00:02:01,500 the other router can take over as the secondary one, 60 00:02:01,500 --> 00:02:03,074 and it'll carry all the data from that switch 61 00:02:03,074 --> 00:02:04,650 out to the network. 62 00:02:04,650 --> 00:02:06,150 This will then give me redundancy 63 00:02:06,150 --> 00:02:08,820 by allowing us to have different pathways out of that switch 64 00:02:08,820 --> 00:02:11,160 by using these two different network connections. 65 00:02:11,160 --> 00:02:11,993 So as you can see, 66 00:02:11,993 --> 00:02:13,589 when you're planning for network redundancy, 67 00:02:13,589 --> 00:02:15,570 you really need to start thinking about this 68 00:02:15,570 --> 00:02:17,280 in three different parts. 69 00:02:17,280 --> 00:02:18,649 You need to think about it as the device, 70 00:02:18,649 --> 00:02:21,734 those network interface cards and the cables themself. 71 00:02:21,734 --> 00:02:23,970 Also, you need to think about it from the router 72 00:02:23,970 --> 00:02:26,370 and switch perspective to make sure you have redundant paths 73 00:02:26,370 --> 00:02:28,800 inside of your network and out to the internet as well 74 00:02:28,800 --> 00:02:31,260 when you're making external connections. 75 00:02:31,260 --> 00:02:33,030 All right, now that we've covered some of the basics, 76 00:02:33,030 --> 00:02:35,400 let's explore some different high availability approaches 77 00:02:35,400 --> 00:02:37,170 or strategies that we can utilize 78 00:02:37,170 --> 00:02:38,790 to achieve higher levels of availability 79 00:02:38,790 --> 00:02:40,680 and redundancy in our networks. 80 00:02:40,680 --> 00:02:43,050 This includes things like active-active approaches, 81 00:02:43,050 --> 00:02:44,242 active-passive approaches, 82 00:02:44,242 --> 00:02:46,740 the use of hardware devices like load balancers, 83 00:02:46,740 --> 00:02:49,110 and the use of content delivery networks. 84 00:02:49,110 --> 00:02:50,400 First, let's explore 85 00:02:50,400 --> 00:02:53,220 the active-active approach to high availability. 86 00:02:53,220 --> 00:02:55,140 Now, inside of an active-active setup, 87 00:02:55,140 --> 00:02:57,102 multiple systems will be run simultaneously 88 00:02:57,102 --> 00:02:59,730 and they'll share the load and provide seamless service 89 00:02:59,730 --> 00:03:02,010 even if one or more of those systems fail. 90 00:03:02,010 --> 00:03:04,560 This approach will maximize resource utilization 91 00:03:04,560 --> 00:03:06,720 and ensure that the service can handle the load 92 00:03:06,720 --> 00:03:09,000 even in a case of a system failure. 93 00:03:09,000 --> 00:03:11,130 For example, if I have two network cards 94 00:03:11,130 --> 00:03:13,110 installed in my network-attached file server, 95 00:03:13,110 --> 00:03:15,306 and each card operates at one gigabit per second, 96 00:03:15,306 --> 00:03:17,670 I can put them in a load balance configuration 97 00:03:17,670 --> 00:03:19,830 that supports the active-active configuration. 98 00:03:19,830 --> 00:03:21,604 And that way, if both cards are operating, 99 00:03:21,604 --> 00:03:23,130 they'll be working together 100 00:03:23,130 --> 00:03:26,520 to provide a combined throughput of two gigabits per second. 101 00:03:26,520 --> 00:03:27,960 But if one of those network connections 102 00:03:27,960 --> 00:03:29,280 goes down for any reason, 103 00:03:29,280 --> 00:03:31,290 the other one is already there and working. 104 00:03:31,290 --> 00:03:33,629 So it's going to continue to work because it's already active. 105 00:03:33,629 --> 00:03:35,970 The only difference that we're going to see as an end user 106 00:03:35,970 --> 00:03:38,400 is that our speed or our throughput has gone down 107 00:03:38,400 --> 00:03:39,840 because it's been cut in half 108 00:03:39,840 --> 00:03:41,880 because we lost one of those two connectionsm 109 00:03:41,880 --> 00:03:43,500 so we went from one gigabit per second 110 00:03:43,500 --> 00:03:44,910 plus one gigabit per second, 111 00:03:44,910 --> 00:03:46,880 or two gigabits per second of combined throughput 112 00:03:46,880 --> 00:03:49,980 down to only a single one gigabit per second connection. 113 00:03:49,980 --> 00:03:50,813 And that means we only have 114 00:03:50,813 --> 00:03:51,960 one gigabit per second of throughput 115 00:03:51,960 --> 00:03:53,663 that we can use for our systems. 116 00:03:53,663 --> 00:03:55,530 Now the second thing we need to discuss 117 00:03:55,530 --> 00:03:58,530 is an active-passive approach to high availability. 118 00:03:58,530 --> 00:04:00,510 When we're using an active-passive approach, 119 00:04:00,510 --> 00:04:01,830 our systems are going to be configured 120 00:04:01,830 --> 00:04:04,050 so that a standby system will remain idle 121 00:04:04,050 --> 00:04:06,090 until the primary system fails. 122 00:04:06,090 --> 00:04:08,250 When the primary or active system fails, 123 00:04:08,250 --> 00:04:10,110 then our standby system will go in 124 00:04:10,110 --> 00:04:12,090 and take over to ensure that the continuity 125 00:04:12,090 --> 00:04:15,060 of our services will remain available and online. 126 00:04:15,060 --> 00:04:16,740 Now, one thing to note about this approach 127 00:04:16,740 --> 00:04:18,360 is that it may not utilize resources 128 00:04:18,360 --> 00:04:21,029 as efficiently as an active-active setup, 129 00:04:21,029 --> 00:04:22,230 but it does still provide 130 00:04:22,230 --> 00:04:25,080 a reliable fallback mechanism for us to use. 131 00:04:25,080 --> 00:04:26,460 Let me give you a real-world example 132 00:04:26,460 --> 00:04:29,190 of an active-active and active-passive setup. 133 00:04:29,190 --> 00:04:30,540 Now at my old office building, 134 00:04:30,540 --> 00:04:31,500 our power was configured 135 00:04:31,500 --> 00:04:33,450 to use an active standby configuration 136 00:04:33,450 --> 00:04:34,830 when we first moved in. 137 00:04:34,830 --> 00:04:36,420 Because our offices were located in a region 138 00:04:36,420 --> 00:04:38,850 where hurricanes and power outages occurred often, 139 00:04:38,850 --> 00:04:41,970 the previous owner had installed a large diesel generator. 140 00:04:41,970 --> 00:04:43,890 Anytime the power to the building was lost, 141 00:04:43,890 --> 00:04:45,300 the generator would detect that, 142 00:04:45,300 --> 00:04:46,350 it would start itself up 143 00:04:46,350 --> 00:04:47,670 in response to the power loss, 144 00:04:47,670 --> 00:04:49,620 and after about 30 to 60 seconds, 145 00:04:49,620 --> 00:04:52,050 it would come online and take over providing power 146 00:04:52,050 --> 00:04:53,400 until the primary power source 147 00:04:53,400 --> 00:04:55,192 was available for us to use again. 148 00:04:55,192 --> 00:04:56,370 Now, unfortunately, 149 00:04:56,370 --> 00:04:58,230 this left us in the dark for about a minute 150 00:04:58,230 --> 00:04:59,820 while that generator was turning on 151 00:04:59,820 --> 00:05:01,470 and getting ready to assume the power loads 152 00:05:01,470 --> 00:05:02,460 to run the building, 153 00:05:02,460 --> 00:05:03,630 and we really didn't like this setup 154 00:05:03,630 --> 00:05:06,240 from a high availability or redundancy perspective, 155 00:05:06,240 --> 00:05:07,560 and so we decided to change it 156 00:05:07,560 --> 00:05:09,810 from this active-passive mode into something 157 00:05:09,810 --> 00:05:12,750 that uses an active-active configuration instead. 158 00:05:12,750 --> 00:05:13,583 To achieve this, 159 00:05:13,583 --> 00:05:15,300 we first installed 60 solar panels 160 00:05:15,300 --> 00:05:16,408 to generate enough electricity 161 00:05:16,408 --> 00:05:18,630 to be our primary power source. 162 00:05:18,630 --> 00:05:20,685 Then we installed an electrical transfer switch 163 00:05:20,685 --> 00:05:22,080 that would automatically go 164 00:05:22,080 --> 00:05:23,970 from the solar panels to the electrical grid 165 00:05:23,970 --> 00:05:25,530 anytime we're not getting enough power generated 166 00:05:25,530 --> 00:05:26,820 by those solar panels 167 00:05:26,820 --> 00:05:28,964 because maybe it's a cloudy day or something like that. 168 00:05:28,964 --> 00:05:32,190 This was effectively an active standby configuration, 169 00:05:32,190 --> 00:05:34,020 similar to what we discussed with a generator, 170 00:05:34,020 --> 00:05:35,490 because we would use all solar 171 00:05:35,490 --> 00:05:38,820 or we would use all electric power company provided grid, 172 00:05:38,820 --> 00:05:41,520 we wouldn't use both of them at the same time. 173 00:05:41,520 --> 00:05:44,010 Now, to achieve an active-active configuration, 174 00:05:44,010 --> 00:05:45,300 we actually went ahead and installed 175 00:05:45,300 --> 00:05:47,460 an always on battery backup system. 176 00:05:47,460 --> 00:05:48,293 By using this system, 177 00:05:48,293 --> 00:05:50,610 our solar panels would first fill the batteries, 178 00:05:50,610 --> 00:05:52,050 and then the batteries would discharge 179 00:05:52,050 --> 00:05:53,940 the power into the office building. 180 00:05:53,940 --> 00:05:55,448 If the solar went down for any reason, 181 00:05:55,448 --> 00:05:57,030 we actually wouldn't even notice it 182 00:05:57,030 --> 00:05:59,880 because the battery backup will continue to provide power 183 00:05:59,880 --> 00:06:01,620 for between four and seven days 184 00:06:01,620 --> 00:06:03,657 based on the system size that we had installed 185 00:06:03,657 --> 00:06:06,090 and our level of power utilization. 186 00:06:06,090 --> 00:06:07,290 So hopefully you can see the difference here 187 00:06:07,290 --> 00:06:09,019 between the active passive configuration 188 00:06:09,019 --> 00:06:11,550 where we are using one of two power sources 189 00:06:11,550 --> 00:06:13,590 with the ability to switch to the second one 190 00:06:13,590 --> 00:06:15,450 and an active-active configuration 191 00:06:15,450 --> 00:06:17,310 where we are constantly feeding the batteries, 192 00:06:17,310 --> 00:06:18,840 and then those batteries are feeding the power 193 00:06:18,840 --> 00:06:19,740 to our building, 194 00:06:19,740 --> 00:06:23,550 so we always can use both power sources at the same time. 195 00:06:23,550 --> 00:06:26,099 Now, third, let's take a look at load balancers. 196 00:06:26,099 --> 00:06:28,230 Load balancers are going to function inside 197 00:06:28,230 --> 00:06:30,240 of our high availability approaches as well, 198 00:06:30,240 --> 00:06:32,160 and they're going to be used to distribute network traffic 199 00:06:32,160 --> 00:06:33,870 across multiple servers to ensure 200 00:06:33,870 --> 00:06:35,959 that no single server will bear too much load, 201 00:06:35,959 --> 00:06:38,040 and this way we can maintain higher levels 202 00:06:38,040 --> 00:06:39,593 of performance and uptime. 203 00:06:39,593 --> 00:06:42,450 These load balancers really do play a crucial role 204 00:06:42,450 --> 00:06:43,950 in an active-active setup 205 00:06:43,950 --> 00:06:46,050 by efficiently distributing incoming requests 206 00:06:46,050 --> 00:06:48,060 to the best available resources. 207 00:06:48,060 --> 00:06:50,100 Load balancers also will continuously 208 00:06:50,100 --> 00:06:51,480 monitor the health of the servers, 209 00:06:51,480 --> 00:06:53,040 and they can reroute your traffic away 210 00:06:53,040 --> 00:06:56,310 from failed nodes to maintain uninterrupted services. 211 00:06:56,310 --> 00:06:58,529 Fourth, we have content delivery networks. 212 00:06:58,529 --> 00:07:00,711 Content delivery network or CDN 213 00:07:00,711 --> 00:07:02,220 is another vital component 214 00:07:02,220 --> 00:07:04,259 in achieving high levels of availability. 215 00:07:04,259 --> 00:07:06,900 A content delivery network is a network of servers 216 00:07:06,900 --> 00:07:08,204 that are distributed geographically 217 00:07:08,204 --> 00:07:12,000 to deliver content to users more efficiently and reliably. 218 00:07:12,000 --> 00:07:15,232 CDNs can also store cash content closer to the end users, 219 00:07:15,232 --> 00:07:16,740 so we can reduce the latency 220 00:07:16,740 --> 00:07:19,080 and lower the load times for those end users 221 00:07:19,080 --> 00:07:21,270 when they're trying to access those services. 222 00:07:21,270 --> 00:07:24,210 Now, in the case of a server failure or excessive traffic, 223 00:07:24,210 --> 00:07:25,246 our content delivery networks 224 00:07:25,246 --> 00:07:26,970 can simply reroute the request 225 00:07:26,970 --> 00:07:28,710 to the next closest server to ensure 226 00:07:28,710 --> 00:07:30,840 that our end users experience remains unaffected 227 00:07:30,840 --> 00:07:32,430 by the loss of a single server 228 00:07:32,430 --> 00:07:34,800 or higher than expected network traffic loads 229 00:07:34,800 --> 00:07:36,270 being experienced. 230 00:07:36,270 --> 00:07:38,393 Now, when it comes to implementing high availability, 231 00:07:38,393 --> 00:07:40,980 it's important that you design the network with redundancy 232 00:07:40,980 --> 00:07:41,813 at its core. 233 00:07:41,813 --> 00:07:43,380 Redundancy can be achieved 234 00:07:43,380 --> 00:07:45,300 by deploying multiple network interface cards 235 00:07:45,300 --> 00:07:46,560 inside of your servers, 236 00:07:46,560 --> 00:07:48,870 and this way, you can support both load balancing 237 00:07:48,870 --> 00:07:51,690 and redundancy by ensuring that multiple pathways exist 238 00:07:51,690 --> 00:07:53,190 between your switches and routers, 239 00:07:53,190 --> 00:07:55,140 as well as by having redundant internet connections 240 00:07:55,140 --> 00:07:56,460 for your use too. 241 00:07:56,460 --> 00:07:59,160 By combining these infrastructure setups with active-active 242 00:07:59,160 --> 00:08:01,920 or active-passive approaches and integrating load balancers 243 00:08:01,920 --> 00:08:03,900 and CDNs, your enterprise network 244 00:08:03,900 --> 00:08:06,570 can achieve high availability, minimize its downtime, 245 00:08:06,570 --> 00:08:08,760 and provide a seamless user experience. 246 00:08:08,760 --> 00:08:10,661 So remember, high availability approaches 247 00:08:10,661 --> 00:08:13,093 include things like active-active configurations 248 00:08:13,093 --> 00:08:15,330 and active-passive configuration, 249 00:08:15,330 --> 00:08:16,680 leveraging load balancers, 250 00:08:16,680 --> 00:08:18,990 or implementing a content delivery network 251 00:08:18,990 --> 00:08:20,880 so that you can maintain continuous operations 252 00:08:20,880 --> 00:08:22,410 and higher levels of performance 253 00:08:22,410 --> 00:08:24,570 in enterprise networks and services. 254 00:08:24,570 --> 00:08:26,310 These strategies can also be combined 255 00:08:26,310 --> 00:08:27,780 with a robust network design 256 00:08:27,780 --> 00:08:30,154 that can focus on integrating redundancy into your systems 257 00:08:30,154 --> 00:08:31,680 so that you can ensure your business 258 00:08:31,680 --> 00:08:33,780 can provide reliable and efficient services 259 00:08:33,780 --> 00:08:34,953 to its end users.