1 00:00:00,000 --> 00:00:00,990 In this lesson, 2 00:00:00,990 --> 00:00:03,810 we're going to discuss wired network topologies. 3 00:00:03,810 --> 00:00:06,060 Now, a network topology refers to the arrangement 4 00:00:06,060 --> 00:00:08,940 of different elements like the links, nodes, clients, 5 00:00:08,940 --> 00:00:11,790 and servers that make up a computer network. 6 00:00:11,790 --> 00:00:13,170 It is crucial that you understand 7 00:00:13,170 --> 00:00:14,730 the different types of network topologies 8 00:00:14,730 --> 00:00:16,530 when you attempt to design an efficient 9 00:00:16,530 --> 00:00:18,720 and resilient network infrastructure. 10 00:00:18,720 --> 00:00:20,550 Now, before we cover the six different types 11 00:00:20,550 --> 00:00:22,500 of network topologies that we can use, 12 00:00:22,500 --> 00:00:23,640 we first need to understand 13 00:00:23,640 --> 00:00:25,800 how these topologies are going to be documented 14 00:00:25,800 --> 00:00:27,540 in our network diagrams. 15 00:00:27,540 --> 00:00:28,920 Generally, you're going to find 16 00:00:28,920 --> 00:00:31,380 that network diagrams are going to document our topologies 17 00:00:31,380 --> 00:00:33,090 using either a physical topology 18 00:00:33,090 --> 00:00:35,160 or a logical topology. 19 00:00:35,160 --> 00:00:37,320 Now, a physical topology is used to show 20 00:00:37,320 --> 00:00:39,150 how the network devices and components 21 00:00:39,150 --> 00:00:41,460 are physically cabled and connected together 22 00:00:41,460 --> 00:00:44,310 using various types of copper or fiber media. 23 00:00:44,310 --> 00:00:46,050 For example, if I wanted to show 24 00:00:46,050 --> 00:00:48,210 where all the different network computers, routers, 25 00:00:48,210 --> 00:00:49,170 and switches are located 26 00:00:49,170 --> 00:00:50,820 inside of my office building, 27 00:00:50,820 --> 00:00:52,920 I could get a copy of the building's floor plan 28 00:00:52,920 --> 00:00:54,930 and then document where each of those devices 29 00:00:54,930 --> 00:00:57,540 and those cables are located in that building 30 00:00:57,540 --> 00:01:00,570 by drawing it over the floor plan for the office. 31 00:01:00,570 --> 00:01:01,560 On the other hand, 32 00:01:01,560 --> 00:01:03,060 we can also document our network 33 00:01:03,060 --> 00:01:05,010 using a logical topology. 34 00:01:05,010 --> 00:01:07,080 When we talk about logical topologies, 35 00:01:07,080 --> 00:01:07,950 we're really talking about 36 00:01:07,950 --> 00:01:09,060 how the traffic is actually 37 00:01:09,060 --> 00:01:10,830 going to flow through our network. 38 00:01:10,830 --> 00:01:12,330 On a logical diagram, 39 00:01:12,330 --> 00:01:14,340 you're going to see where the workstations are, 40 00:01:14,340 --> 00:01:15,360 where the routers are, 41 00:01:15,360 --> 00:01:16,290 where the switches are, 42 00:01:16,290 --> 00:01:18,810 and how all that stuff is going to be connected. 43 00:01:18,810 --> 00:01:21,210 But this diagram doesn't actually show 44 00:01:21,210 --> 00:01:23,730 the location of each device in the real world 45 00:01:23,730 --> 00:01:26,340 by displaying it on top of a floor plan. 46 00:01:26,340 --> 00:01:28,650 For example, just because a server is shown 47 00:01:28,650 --> 00:01:31,140 in the upper right-hand corner of a logical diagram 48 00:01:31,140 --> 00:01:32,190 doesn't mean this locate 49 00:01:32,190 --> 00:01:33,360 in the upper-right hand corner 50 00:01:33,360 --> 00:01:34,830 of your office building. 51 00:01:34,830 --> 00:01:36,900 Instead, you may have several devices 52 00:01:36,900 --> 00:01:38,610 that are shown on the logical diagram 53 00:01:38,610 --> 00:01:40,320 that are located within the same room 54 00:01:40,320 --> 00:01:41,790 or on different floors 55 00:01:41,790 --> 00:01:43,590 or even in different buildings. 56 00:01:43,590 --> 00:01:44,730 And it really doesn't matter 57 00:01:44,730 --> 00:01:46,680 when you're dealing with a logical topology 58 00:01:46,680 --> 00:01:48,000 because we just want to know 59 00:01:48,000 --> 00:01:50,310 how they're connected logically in the network 60 00:01:50,310 --> 00:01:52,530 and how the data is going to flow. 61 00:01:52,530 --> 00:01:54,180 Within a logical topology, 62 00:01:54,180 --> 00:01:55,440 I'm really just concerned with the way 63 00:01:55,440 --> 00:01:57,060 that the data is flowing in the network 64 00:01:57,060 --> 00:01:58,620 and not the way it's actually cabled 65 00:01:58,620 --> 00:02:01,350 in the physical or real-world environment. 66 00:02:01,350 --> 00:02:03,330 For right now, it's not really important 67 00:02:03,330 --> 00:02:05,760 that you can understand or read these diagrams 68 00:02:05,760 --> 00:02:07,980 or it's associated symbols and icons. 69 00:02:07,980 --> 00:02:09,990 But instead, I just want you to realize 70 00:02:09,990 --> 00:02:10,889 that there is a difference 71 00:02:10,889 --> 00:02:13,260 between a logical and a physical topology, 72 00:02:13,260 --> 00:02:14,610 and the difference is the one 73 00:02:14,610 --> 00:02:16,080 is being focused on the logical 74 00:02:16,080 --> 00:02:17,550 or network flow of the data, 75 00:02:17,550 --> 00:02:18,840 while the other one is focused 76 00:02:18,840 --> 00:02:20,430 on the physical layout of the cabling 77 00:02:20,430 --> 00:02:23,490 and the devices in your real-world environments. 78 00:02:23,490 --> 00:02:25,680 Now, I mentioned there are six different topologies 79 00:02:25,680 --> 00:02:27,600 that we're going to cover in this lesson, 80 00:02:27,600 --> 00:02:29,580 so let's take a look at point-to-point, 81 00:02:29,580 --> 00:02:32,730 ring, bus, star, hub-and-spoke, 82 00:02:32,730 --> 00:02:35,730 and mesh apologies as we continue on. 83 00:02:35,730 --> 00:02:38,280 First, we have point-to-point topologies. 84 00:02:38,280 --> 00:02:39,690 Now a point-to-point topology 85 00:02:39,690 --> 00:02:41,940 is the simplest form of a network topology 86 00:02:41,940 --> 00:02:44,970 because it involves a direct connection between two devices. 87 00:02:44,970 --> 00:02:47,190 Point-to-point topologies are often going to be used 88 00:02:47,190 --> 00:02:49,260 for connecting a computer to a network peripheral, 89 00:02:49,260 --> 00:02:51,060 like a printer or a scanner. 90 00:02:51,060 --> 00:02:52,230 While this is a straightforward 91 00:02:52,230 --> 00:02:54,870 and reliable method for creating small-scale connections, 92 00:02:54,870 --> 00:02:56,430 it's not really going to be scalable 93 00:02:56,430 --> 00:02:57,990 for our larger networks. 94 00:02:57,990 --> 00:02:59,010 Now, the only exception 95 00:02:59,010 --> 00:03:00,690 to point-to-point topologies being used 96 00:03:00,690 --> 00:03:02,640 in large enterprise-scale networks 97 00:03:02,640 --> 00:03:05,700 is really for your wide-area network or WAN connections, 98 00:03:05,700 --> 00:03:06,570 because you can connect 99 00:03:06,570 --> 00:03:09,060 one of your company's remote offices in California 100 00:03:09,060 --> 00:03:11,580 all the way back to your headquarters office in New York 101 00:03:11,580 --> 00:03:13,770 using a point-to-point fiber optic connection 102 00:03:13,770 --> 00:03:15,900 between those two facilities. 103 00:03:15,900 --> 00:03:18,420 Second, we have ring topologies. 104 00:03:18,420 --> 00:03:20,790 Now, a ring topology is a network configuration 105 00:03:20,790 --> 00:03:23,340 where each device is connected to two other devices, 106 00:03:23,340 --> 00:03:25,680 and this forms a circular data path. 107 00:03:25,680 --> 00:03:28,500 In this setup, data is going to travel in one direction, 108 00:03:28,500 --> 00:03:30,600 either clockwise or counterclockwise 109 00:03:30,600 --> 00:03:32,730 until it reaches its destination. 110 00:03:32,730 --> 00:03:35,130 Now, one of the benefits of using ring topologies 111 00:03:35,130 --> 00:03:36,750 is that it's going to prevent data collisions 112 00:03:36,750 --> 00:03:39,210 due to using this unidirectional flow. 113 00:03:39,210 --> 00:03:41,700 However, if one node fails in the ring, 114 00:03:41,700 --> 00:03:43,410 it can disrupt the entire network 115 00:03:43,410 --> 00:03:46,200 unless there are redundant connections for failover. 116 00:03:46,200 --> 00:03:49,230 Now, these days, ring networks are not very common 117 00:03:49,230 --> 00:03:50,580 unless you're going to be using 118 00:03:50,580 --> 00:03:52,800 a Fiber Distributed Data Interface 119 00:03:52,800 --> 00:03:56,100 known as an FDDI or FDDI connection. 120 00:03:56,100 --> 00:03:57,960 Now, a FDDI connection is going to be used 121 00:03:57,960 --> 00:03:59,340 to conduct data transmissions 122 00:03:59,340 --> 00:04:00,720 on fiber optic lines 123 00:04:00,720 --> 00:04:01,827 in a local area network 124 00:04:01,827 --> 00:04:03,360 and can actually extend up to 125 00:04:03,360 --> 00:04:05,370 a range of about 200 kilometers, 126 00:04:05,370 --> 00:04:08,220 which is about 125 miles in range. 127 00:04:08,220 --> 00:04:09,720 Now, a FDDI ring is going to operate 128 00:04:09,720 --> 00:04:11,250 on a dual ring structure, 129 00:04:11,250 --> 00:04:12,450 and this provides redundancy 130 00:04:12,450 --> 00:04:14,730 with a primary and secondary ring. 131 00:04:14,730 --> 00:04:16,860 If the primary ring fails for some reason, 132 00:04:16,860 --> 00:04:20,310 that secondary ring can maintain network operations for you. 133 00:04:20,310 --> 00:04:22,620 FDDI is really well known for high bandwidth, 134 00:04:22,620 --> 00:04:23,940 and this makes it really suitable 135 00:04:23,940 --> 00:04:25,890 for environments with large data transfers 136 00:04:25,890 --> 00:04:27,750 and high reliability requirements 137 00:04:27,750 --> 00:04:30,900 such as campus area networks or data centers. 138 00:04:30,900 --> 00:04:32,790 Third, we have bus topologies. 139 00:04:32,790 --> 00:04:34,650 Now, in a bus topology, 140 00:04:34,650 --> 00:04:36,480 all the network devices are going to be connected 141 00:04:36,480 --> 00:04:38,370 back to a single central cable, 142 00:04:38,370 --> 00:04:41,310 which is known as the backbone or the bus. 143 00:04:41,310 --> 00:04:42,930 Data can be sent by any device 144 00:04:42,930 --> 00:04:43,763 and it's going to be available 145 00:04:43,763 --> 00:04:45,930 to every other device on that bus 146 00:04:45,930 --> 00:04:48,030 but only the intended recipient, 147 00:04:48,030 --> 00:04:49,950 which is identified by a unique address, 148 00:04:49,950 --> 00:04:52,770 will actually process the message that it's seeing. 149 00:04:52,770 --> 00:04:55,320 While bus topologies are really easy to install 150 00:04:55,320 --> 00:04:57,300 and they require less cable than other layouts, 151 00:04:57,300 --> 00:04:59,820 they do have some significant limitations. 152 00:04:59,820 --> 00:05:01,470 The entire network can be disabled 153 00:05:01,470 --> 00:05:03,060 if that main cable fails, 154 00:05:03,060 --> 00:05:04,920 and as more devices are added, 155 00:05:04,920 --> 00:05:07,590 the performance of that whole network will decrease 156 00:05:07,590 --> 00:05:10,680 due to more data collisions happening on that cable. 157 00:05:10,680 --> 00:05:12,180 Similar to a ring network, 158 00:05:12,180 --> 00:05:13,350 bus networks are considered 159 00:05:13,350 --> 00:05:14,700 to be an older technology, 160 00:05:14,700 --> 00:05:15,840 and they're not commonly used 161 00:05:15,840 --> 00:05:17,070 in our modern home office 162 00:05:17,070 --> 00:05:19,140 or small office environments. 163 00:05:19,140 --> 00:05:21,210 Fourth, we have the star topology. 164 00:05:21,210 --> 00:05:22,260 Now, the star topology 165 00:05:22,260 --> 00:05:23,850 is one of the most common network layouts 166 00:05:23,850 --> 00:05:25,110 that's in use today, 167 00:05:25,110 --> 00:05:26,190 and your own home network 168 00:05:26,190 --> 00:05:29,460 is most likely using a star topology right now. 169 00:05:29,460 --> 00:05:30,810 In a star topology, 170 00:05:30,810 --> 00:05:31,860 each node in the network 171 00:05:31,860 --> 00:05:32,693 is going to be connected 172 00:05:32,693 --> 00:05:34,740 back to a centralized connection point, 173 00:05:34,740 --> 00:05:37,470 which is normally going to be a network switch. 174 00:05:37,470 --> 00:05:39,450 That switch can also act as a repeater 175 00:05:39,450 --> 00:05:41,160 for your network's data flow. 176 00:05:41,160 --> 00:05:42,810 This type of star configuration 177 00:05:42,810 --> 00:05:44,520 is considered to be very robust 178 00:05:44,520 --> 00:05:45,930 because the failure of one link 179 00:05:45,930 --> 00:05:48,120 doesn't affect any of the other links. 180 00:05:48,120 --> 00:05:49,710 However, the entire network 181 00:05:49,710 --> 00:05:51,060 does depend on the functioning 182 00:05:51,060 --> 00:05:52,980 of that centralized connection point, 183 00:05:52,980 --> 00:05:54,870 that network switch that we just talked about. 184 00:05:54,870 --> 00:05:56,550 So if that switch fails, 185 00:05:56,550 --> 00:05:59,040 your entire network will become inoperable 186 00:05:59,040 --> 00:06:01,380 if you're using a star topology. 187 00:06:01,380 --> 00:06:04,410 Now, fifth, we have a hub-and-spoke topology. 188 00:06:04,410 --> 00:06:05,790 Now, the hub-and-spoke topology 189 00:06:05,790 --> 00:06:07,860 is a variation of the star topology 190 00:06:07,860 --> 00:06:09,180 where the centralized node, 191 00:06:09,180 --> 00:06:10,980 which we're going to call a hub in this case, 192 00:06:10,980 --> 00:06:12,450 is connected to multiple nodes, 193 00:06:12,450 --> 00:06:14,070 which we call spokes. 194 00:06:14,070 --> 00:06:16,710 These spokes are not directly connected to each other, 195 00:06:16,710 --> 00:06:19,200 so they must transmit their data to one of the hubs 196 00:06:19,200 --> 00:06:21,660 before that data is going to be forwarded to another hub 197 00:06:21,660 --> 00:06:25,080 and then onward to the final destination node in that spoke. 198 00:06:25,080 --> 00:06:27,240 This layout is commonly used in airlines 199 00:06:27,240 --> 00:06:29,580 as well as in telecommunication networks. 200 00:06:29,580 --> 00:06:31,680 For example, if I wanted to take a flight 201 00:06:31,680 --> 00:06:34,530 from Orlando, Florida, over to Honolulu, Hawaii, 202 00:06:34,530 --> 00:06:36,090 I probably am not going to be able to find 203 00:06:36,090 --> 00:06:38,940 a direct point-to-point or nonstop flight. 204 00:06:38,940 --> 00:06:41,460 Instead, I may choose to fly on Delta, 205 00:06:41,460 --> 00:06:42,300 which will then fly me 206 00:06:42,300 --> 00:06:44,040 from Orlando over to Atlanta, 207 00:06:44,040 --> 00:06:45,540 which is one of their hub cities, 208 00:06:45,540 --> 00:06:47,160 and then I'll switch planes. 209 00:06:47,160 --> 00:06:48,030 I'll get on that plane 210 00:06:48,030 --> 00:06:49,170 and fly to Los Angeles, 211 00:06:49,170 --> 00:06:51,360 which is another one of Delta's hub cities. 212 00:06:51,360 --> 00:06:52,320 And then from there, 213 00:06:52,320 --> 00:06:53,820 I'll switch onto another plane 214 00:06:53,820 --> 00:06:54,930 and I'll take that plane 215 00:06:54,930 --> 00:06:57,330 from Los Angeles over to Hawaii. 216 00:06:57,330 --> 00:06:59,910 Now, if I instead decide to fly with American Airlines, 217 00:06:59,910 --> 00:07:01,380 they use a different set of hubs 218 00:07:01,380 --> 00:07:02,850 for their hub-and-spoke model. 219 00:07:02,850 --> 00:07:04,710 So I might go from Orlando 220 00:07:04,710 --> 00:07:07,290 over to the American Airlines' Dallas-Fort Worth hub, 221 00:07:07,290 --> 00:07:08,700 and then switch planes in Dallas 222 00:07:08,700 --> 00:07:09,840 and board a long flight 223 00:07:09,840 --> 00:07:12,570 all the way out to Hawaii from Texas. 224 00:07:12,570 --> 00:07:14,430 In either case, because we're operating 225 00:07:14,430 --> 00:07:15,960 under this hub-and-spoke model, 226 00:07:15,960 --> 00:07:17,550 the other passengers can be flying in 227 00:07:17,550 --> 00:07:18,660 from all of the other cities 228 00:07:18,660 --> 00:07:20,640 around the U.S. to that hub, 229 00:07:20,640 --> 00:07:22,380 and then we'll all get on the plane together 230 00:07:22,380 --> 00:07:24,780 and go from that hub over to Hawaii. 231 00:07:24,780 --> 00:07:26,070 This is exactly what happens 232 00:07:26,070 --> 00:07:27,300 in the hub-and-spoke model 233 00:07:27,300 --> 00:07:29,520 when we're dealing with our networks as well. 234 00:07:29,520 --> 00:07:31,530 Now, this means that we're going to be able to consolidate 235 00:07:31,530 --> 00:07:33,420 a lot of our smaller regional offices 236 00:07:33,420 --> 00:07:35,460 in one region like the Northeast 237 00:07:35,460 --> 00:07:37,800 over to a hub, maybe in New York City, 238 00:07:37,800 --> 00:07:39,240 and that way I could take the data 239 00:07:39,240 --> 00:07:40,530 from the New York City office 240 00:07:40,530 --> 00:07:41,430 and send it all the way over 241 00:07:41,430 --> 00:07:42,690 to our Los Angeles office, 242 00:07:42,690 --> 00:07:43,860 which is another hub, 243 00:07:43,860 --> 00:07:44,693 and then from there, 244 00:07:44,693 --> 00:07:45,540 it would spread out to the other 245 00:07:45,540 --> 00:07:47,820 regional offices in California. 246 00:07:47,820 --> 00:07:48,780 By doing this, 247 00:07:48,780 --> 00:07:50,700 we can have these two larger data centers 248 00:07:50,700 --> 00:07:52,680 having a really big, high, fast, 249 00:07:52,680 --> 00:07:54,090 high bandwidth connection 250 00:07:54,090 --> 00:07:56,310 that can transfer all the data for us very quickly 251 00:07:56,310 --> 00:07:57,750 from those smaller regional offices 252 00:07:57,750 --> 00:07:59,250 all the way across the country. 253 00:07:59,250 --> 00:08:00,510 And this can save us a lot of money 254 00:08:00,510 --> 00:08:01,350 by not having to connect 255 00:08:01,350 --> 00:08:03,090 every one of those smaller offices 256 00:08:03,090 --> 00:08:04,740 to each of the other smaller offices 257 00:08:04,740 --> 00:08:05,880 all over the country 258 00:08:05,880 --> 00:08:08,970 because those long distance links get really expensive. 259 00:08:08,970 --> 00:08:12,120 Sixth, and finally, we have the mesh topology. 260 00:08:12,120 --> 00:08:13,980 Now, the mesh topology is going to feature 261 00:08:13,980 --> 00:08:15,060 a point-to-point connection 262 00:08:15,060 --> 00:08:17,370 between every single device on the network 263 00:08:17,370 --> 00:08:19,980 to create a robust and redundant network. 264 00:08:19,980 --> 00:08:21,750 Now, there are two types of mesh topologies 265 00:08:21,750 --> 00:08:22,740 you need to consider. 266 00:08:22,740 --> 00:08:25,020 A full-mesh and a partial-mesh. 267 00:08:25,020 --> 00:08:26,760 Now, a full-mesh topology is one 268 00:08:26,760 --> 00:08:27,930 where every node is connected 269 00:08:27,930 --> 00:08:29,820 to every other node in the network. 270 00:08:29,820 --> 00:08:32,130 This topology provides high redundancy, 271 00:08:32,130 --> 00:08:33,600 but it can be very expensive 272 00:08:33,600 --> 00:08:34,980 and complex to install 273 00:08:34,980 --> 00:08:37,530 because of the number of cables and ports required. 274 00:08:37,530 --> 00:08:40,350 For example, if I have three nodes I need to connect, 275 00:08:40,350 --> 00:08:41,789 I can create this full-mesh 276 00:08:41,789 --> 00:08:44,370 by cabling node one and node two together, 277 00:08:44,370 --> 00:08:47,070 then I cable node two and node three together, 278 00:08:47,070 --> 00:08:48,600 and then I cable node one 279 00:08:48,600 --> 00:08:49,920 and node three together. 280 00:08:49,920 --> 00:08:51,480 This means, for three nodes, 281 00:08:51,480 --> 00:08:53,370 I only need three cables. 282 00:08:53,370 --> 00:08:54,810 That's not so bad. 283 00:08:54,810 --> 00:08:56,970 But if I simply double the number of nodes 284 00:08:56,970 --> 00:08:58,380 from three to six, 285 00:08:58,380 --> 00:08:59,580 I'm actually not going to double 286 00:08:59,580 --> 00:09:01,230 the number of cables required. 287 00:09:01,230 --> 00:09:03,210 Instead, if I have six nodes, 288 00:09:03,210 --> 00:09:05,730 I'm actually going to need 15 connections to ensure 289 00:09:05,730 --> 00:09:07,800 that every node can communicate directly 290 00:09:07,800 --> 00:09:09,360 with every other node. 291 00:09:09,360 --> 00:09:11,700 This is because the number of connections we require 292 00:09:11,700 --> 00:09:13,380 is going to be represented by the formula, 293 00:09:13,380 --> 00:09:16,770 n times n minus one divided by two, 294 00:09:16,770 --> 00:09:18,690 where n is the number of nodes. 295 00:09:18,690 --> 00:09:20,550 So if I have three nodes, 296 00:09:20,550 --> 00:09:24,180 it's three times three minus one divided by two. 297 00:09:24,180 --> 00:09:26,730 This would equal three times two divided by two, 298 00:09:26,730 --> 00:09:28,170 or three. 299 00:09:28,170 --> 00:09:29,970 Now, if I have six nodes, on the other hand, 300 00:09:29,970 --> 00:09:33,840 I'm going to have six times six minus one divided by two. 301 00:09:33,840 --> 00:09:36,480 This would give me six times five divided by two, 302 00:09:36,480 --> 00:09:38,730 which then turns into 30 divided by two, 303 00:09:38,730 --> 00:09:41,070 or 15 different cables. 304 00:09:41,070 --> 00:09:42,960 You can see how impractical this can be 305 00:09:42,960 --> 00:09:43,920 when you start having a network 306 00:09:43,920 --> 00:09:45,870 with a large number of nodes. 307 00:09:45,870 --> 00:09:48,210 So to get the benefits of a mesh network 308 00:09:48,210 --> 00:09:50,610 without having to create a full-mesh network, 309 00:09:50,610 --> 00:09:51,930 we can opt to use what is called 310 00:09:51,930 --> 00:09:54,690 a partial-mesh topology for our networks. 311 00:09:54,690 --> 00:09:56,190 Now, a partial-mesh topology 312 00:09:56,190 --> 00:09:58,110 is a less interlinked version 313 00:09:58,110 --> 00:09:59,370 where some nodes are organized 314 00:09:59,370 --> 00:10:00,720 in a full-mesh scheme 315 00:10:00,720 --> 00:10:02,550 while others are only connected to one 316 00:10:02,550 --> 00:10:04,740 or two devices inside of the network. 317 00:10:04,740 --> 00:10:06,420 So if I have six nodes, 318 00:10:06,420 --> 00:10:08,220 I may decide that only three of those nodes 319 00:10:08,220 --> 00:10:09,840 are my most critical ones, 320 00:10:09,840 --> 00:10:10,740 and they're going to be the ones 321 00:10:10,740 --> 00:10:13,230 that are fully-interconnected in a mesh topology, 322 00:10:13,230 --> 00:10:16,200 while the other three are considered less important nodes, 323 00:10:16,200 --> 00:10:17,910 and they may only connect back to one 324 00:10:17,910 --> 00:10:19,800 or two of those critical nodes 325 00:10:19,800 --> 00:10:20,633 to send their data 326 00:10:20,633 --> 00:10:21,930 between all the different nodes 327 00:10:21,930 --> 00:10:23,550 in that partial-mesh. 328 00:10:23,550 --> 00:10:25,590 So remember, understanding the different types 329 00:10:25,590 --> 00:10:27,450 of wired network topologies is crucial 330 00:10:27,450 --> 00:10:29,460 for network design and management. 331 00:10:29,460 --> 00:10:30,780 Each topology has its 332 00:10:30,780 --> 00:10:32,610 unique advantages and disadvantages 333 00:10:32,610 --> 00:10:35,010 that makes them suitable for various scenarios. 334 00:10:35,010 --> 00:10:36,750 Point-to-point is considered to be simple 335 00:10:36,750 --> 00:10:38,940 and reliable for small-scale connections, 336 00:10:38,940 --> 00:10:39,960 but it's not practical 337 00:10:39,960 --> 00:10:41,460 for larger enterprise networks 338 00:10:41,460 --> 00:10:42,870 most of the time. 339 00:10:42,870 --> 00:10:45,330 Ring and bus topologies will offer simplicity, 340 00:10:45,330 --> 00:10:46,410 but they can be vulnerable 341 00:10:46,410 --> 00:10:47,910 to single points of failure 342 00:10:47,910 --> 00:10:49,680 because you can have the ring cut 343 00:10:49,680 --> 00:10:50,730 or the bus cut, 344 00:10:50,730 --> 00:10:54,150 and that will stop all the communication on that topology. 345 00:10:54,150 --> 00:10:56,820 Star and hub-and-spoke topologies do a good job 346 00:10:56,820 --> 00:10:58,830 of giving you centralized network management, 347 00:10:58,830 --> 00:11:00,180 but they do rely heavily 348 00:11:00,180 --> 00:11:02,280 on the functioning of that central point, 349 00:11:02,280 --> 00:11:04,290 which we call the hub in the hub and spoke, 350 00:11:04,290 --> 00:11:06,960 or the switch inside of our star topologies. 351 00:11:06,960 --> 00:11:08,700 And lastly, the mesh topology 352 00:11:08,700 --> 00:11:10,620 offers robustness and redundancy, 353 00:11:10,620 --> 00:11:12,150 but it can be complex 354 00:11:12,150 --> 00:11:13,470 and costly to implement 355 00:11:13,470 --> 00:11:15,360 because when you're doing a full-mesh, 356 00:11:15,360 --> 00:11:16,710 you have a lot of connections 357 00:11:16,710 --> 00:11:17,990 between all of those nodes. 358 00:11:17,990 --> 00:11:19,560 In a partial-mesh, you're giving up 359 00:11:19,560 --> 00:11:21,780 some of that resiliency and redundancy 360 00:11:21,780 --> 00:11:24,603 in terms of lower cost and higher scale.