WEBVTT 00:00.910 --> 00:08.470 Let's talk about another important networking topic, and it is none other than networking, topologies 00:08.470 --> 00:11.080 and modern types of networks. 00:11.410 --> 00:17.860 This is pretty easy material and I'm betting you know it already, so I won't belabor any of these points. 00:18.340 --> 00:22.270 Well, let's talk about the classic bus topology. 00:22.420 --> 00:31.390 In a bus topology, you have nodes connecting directly to a media and they are all able to use that 00:31.390 --> 00:31.900 media. 00:32.350 --> 00:41.650 This very simplified topology is certainly how Ethernet began its life when we had the twisted pair 00:41.770 --> 00:44.290 and we would do a bus topology. 00:44.500 --> 00:51.460 And one of the reasons this topology was famous and one of the famous components about it was we would 00:51.460 --> 00:58.750 often talk about Terminators because how this worked was the signal might just bounce around on the 00:58.750 --> 00:59.770 cable forever. 00:59.950 --> 01:06.580 So to avoid that, you would have a Terminator or Terminators at each end that would stop the signal 01:06.580 --> 01:08.590 from endlessly looping. 01:09.220 --> 01:16.120 The interesting thing about the bus topology when compared to the popular topologies of networks today, 01:16.330 --> 01:22.720 is that there was no intermediate device that was needed that was doing any kind of a function. 01:23.050 --> 01:31.420 When we think of networks now, we always think of a hub or a transparent switch as providing functionality 01:31.420 --> 01:33.220 that makes the network a reality. 01:33.400 --> 01:36.940 But with the bus network, there was no intermediate device. 01:37.390 --> 01:44.020 Now I'm talking in terms of real old legacy technology here, but one of the things that we need to 01:44.020 --> 01:48.130 realize is the bus is still with us today. 01:48.370 --> 01:56.620 And where you might see this oftentimes is inside of a PC or inside of a router, you might have particular 01:56.620 --> 02:00.850 components that are communicating using the bus stop ology. 02:01.480 --> 02:09.550 Another hugely popular topology is the Star network, and this is what we see in so many networks today. 02:09.760 --> 02:17.290 This is where there is an intermediate device, often shown in diagrams in the center that is going 02:17.290 --> 02:19.990 to be proliferating the traffic communications. 02:20.140 --> 02:23.010 It used to be a hub in today's environments. 02:23.050 --> 02:28.210 It's now a more intelligent layer to, at the very least, transparent switch. 02:28.510 --> 02:34.630 You might even have a fancier switch, of course, that is multilayer, that has the ability to route 02:34.630 --> 02:40.450 and switch and do firewalls and do advanced analysis of packets. 02:40.720 --> 02:43.360 So switches get very sophisticated. 02:43.900 --> 02:50.290 They might be simple layer two switches, relatively inexpensive, or they may be more expensive, much 02:50.290 --> 02:51.460 fancier switches. 02:51.640 --> 02:59.590 But notice the STAR Network does have some intermediate device, like a hub or a switch that is helping 02:59.590 --> 02:59.860 out. 03:00.400 --> 03:07.240 In fact, what we really tend to describe these networks as today is extended star networks, which 03:07.240 --> 03:12.910 means that you have a star that connects to another star that connects to another star, and it makes 03:12.910 --> 03:15.490 this huge like snowflake type design. 03:15.700 --> 03:16.570 So pretty cool. 03:16.750 --> 03:19.540 The star in the extended star are what we see today. 03:20.080 --> 03:26.260 Ring networks are still out there today, though we often see these inside of components like the bus 03:26.260 --> 03:31.900 network or will see these in wide area networking in the ring topology. 03:31.900 --> 03:38.950 Notice there was never a need for termination, but what there was often times done in ring topologies 03:38.950 --> 03:43.570 was some kind of a token or beacon that the communicator would use. 03:43.720 --> 03:48.340 And then when they were done communicating, someone else could grab that beacon or token. 03:48.880 --> 03:53.830 The technology of token ring was where we saw this implemented. 03:54.130 --> 04:01.000 That was a ring type of topology and there was a token that you needed to possess in order to communicate. 04:01.450 --> 04:08.470 While that's legacy technology, you won't find anymore except for in technology museums today, like 04:08.470 --> 04:13.330 I said, you might still find ring type topologies in bands. 04:14.020 --> 04:15.940 We can't forget the mesh network. 04:16.030 --> 04:21.460 Maybe it's a partial mesh where you don't have all nodes connected to every other node. 04:21.550 --> 04:28.480 Or maybe it's the full mesh where all nodes are connecting to all other nodes like shown on the left 04:28.480 --> 04:29.500 here in this diagram. 04:29.680 --> 04:35.020 And that starts to get really expensive and can get much more complex. 04:35.380 --> 04:41.590 But it has the advantage, of course, that full mesh of being extremely fault tolerant. 04:42.250 --> 04:48.550 By the way, when we talk about the partial mesh, the great example of that is often called the hub 04:48.550 --> 04:49.870 and spoke type design. 04:50.050 --> 04:53.380 Yes, that is a partial mass mesh approach. 04:54.280 --> 04:59.220 Well, what if you have some combination of these in the top? 04:59.980 --> 05:01.600 And we often do, of course. 05:01.900 --> 05:06.790 Well, then technically we'd say it's a hybrid network, and that's very realistic for today. 05:07.360 --> 05:14.140 I just want you to keep in mind, though, you'll often be making logical topology diagrams of your 05:14.140 --> 05:19.570 network and then physical, and those are going to be very different diagrams. 05:19.990 --> 05:20.730 Think about it. 05:20.740 --> 05:30.760 A physical diagram is going to show exactly what physical devices and cables traffic is making its way 05:30.760 --> 05:32.800 through from point A to point B. 05:33.130 --> 05:39.040 A logical diagram might just show what the end user experiences. 05:39.310 --> 05:45.910 So imagine that the end user is like, Oh, I'm sending traffic from this client to this server. 05:46.060 --> 05:49.300 So they see it is just an easy point to point thing. 05:49.720 --> 05:57.010 And then they don't realize the physical diagram has them going through maybe four intermediate devices. 05:57.400 --> 05:59.890 So the physical would show all that detail. 06:00.100 --> 06:03.220 The logical might leave that detail out. 06:03.520 --> 06:10.600 So just keep in mind many different types of diagrams based on these many different types of topologies 06:10.690 --> 06:11.950 we might encounter. 06:12.460 --> 06:20.440 Now we've got to talk about the types of networks, and we know there's the local area network that 06:20.440 --> 06:27.340 we can create, and when we need to send data to a much greater geographic distance will use the wide 06:27.340 --> 06:28.150 area network. 06:28.420 --> 06:30.070 But what about a man? 06:30.310 --> 06:37.270 Sometimes I have C-H or E.H. students that are not familiar with the Metropolitan Area Network. 06:37.330 --> 06:45.730 Yeah, this is when we have typically high speed copper or perhaps longer distance fiber that is being 06:45.730 --> 06:51.850 used to connect facilities that are all within a metropolitan area of each other. 06:52.090 --> 06:59.050 Maybe we have a bunch of buildings downtown and they're connected with real high speed copper. 06:59.590 --> 07:01.930 That's a metropolitan area network. 07:02.230 --> 07:08.230 There's also the wide oh my gosh, wireless local area network. 07:08.230 --> 07:08.500 Right. 07:08.500 --> 07:10.540 Or wi fi local area network. 07:10.540 --> 07:12.130 The wireless LAN. 07:12.580 --> 07:17.560 There may be defined a campus area network, a can. 07:18.010 --> 07:25.390 And this is where it gets a little silly because you're probably going to have one organization or one 07:25.390 --> 07:31.020 entity call their metropolitan area network, a campus area network. 07:31.030 --> 07:36.910 And then you may have another company with the exact same type of network called there's a metropolitan 07:36.910 --> 07:39.010 area network instead of a campus area network. 07:39.010 --> 07:46.750 So a lot of these can be used interchangeably on the wireless local area network, of course, is, 07:46.750 --> 07:56.530 you know, very specific to where we are connecting devices over Wi-Fi for the purposes of sharing data. 07:56.530 --> 08:00.250 And there is no wide geographic distance between them. 08:01.240 --> 08:05.200 An interesting one is the virtual local area network. 08:05.440 --> 08:08.260 We do this on our network switches. 08:08.590 --> 08:15.700 You see, switches right out of the box are great because when you take a transparent switch out of 08:15.700 --> 08:22.570 the box and you connect your devices to it, it immediately starts doing the Mac address learning and 08:22.570 --> 08:27.610 the intelligent forwarding and filtering of frames without you having to get involved. 08:27.820 --> 08:30.580 It just immediately starts doing all of that. 08:31.090 --> 08:40.780 Now what it doesn't do, what this device doesn't do is break up the ports into separate broadcast domains. 08:41.050 --> 08:48.040 So unfortunately, by default, sure, the switch is forwarding and filtering the unicast traffic, 08:48.370 --> 08:53.680 but the switch is flooding out all of the broadcasts. 08:54.070 --> 08:55.330 This is not good. 08:55.630 --> 09:04.720 And think about how many hacker type based attacks are going to be leveraging broadcasting capabilities. 09:05.080 --> 09:06.730 This is a weakness. 09:06.880 --> 09:15.250 The broadcast traffic form in TCP IP, really, and we should minimize the proliferation of broadcast 09:15.250 --> 09:15.700 traffic. 09:16.270 --> 09:22.270 So the switch has the ability to carve itself up into virtual local area networks. 09:22.600 --> 09:27.100 That makes for more and smaller broadcast domains. 09:27.310 --> 09:30.850 And this is a great design for the network. 09:31.700 --> 09:35.570 So we have talked about two topics here, haven't we? 09:35.810 --> 09:41.930 Both the network topologies and also those important types of networks. 09:42.290 --> 09:48.620 Yes, this is another place where we need to make flashcards for you, so we will to help you with these 09:48.620 --> 09:49.250 concepts. 09:49.430 --> 09:50.120 Enjoy.