Network Types

In this presentation, we'll talk about the basic characteristics of a local area network, or a LAN. And quite simply, a LAN is a network of computers and other components such as printers, that are located relatively close together. Now, clearly, relatively close in and of itself is a relative term. But in most cases what you'll find is that the LAN is usually relegated to within the confines of a single building.

 

Now in terms of the size, it really doesn't matter, we see here a Large office LAN. [Video description begins] A diagram of a large office LAN displays. A router and three switches connect multiple desktop and laptop PCs together. A callout displays a workstation made up of a desktop PC with connections to a printer, headphones, a laptop, and a smartphone. [Video description ends] It really does come down to the physical space that you are spanning.

 

So when it comes to sizes, really you'll find a wide variety here depending on the requirements of the environment. So an Enterprise LAN typically will be much larger with respect to the number of devices. It could easily be thousands of computers, hundreds of printers, various other devices that might connect. [Video description begins] A diagram of an Enterprise LAN displays. Multiple switches connect a range of desktop and laptop PCs together, along with a network printer. [Video description ends]

 

And then by contrast, you might have what's referred to as the SOHO LAN, which stands for small office home office. And in that kind of scenario you might only see two or three computers and maybe one printer. [Video description begins] A diagram of a SOHO LAN displays. Two switches connect a single desktop PC and two laptop PCs together, along with a network printer. [Video description ends] But really again, the size of the network is not really what matters, it is the actual physical space that you are dealing with.

 

So in terms of advantages and disadvantages, it absolutely gives you the advantage of being able to share resources. So particularly in the larger LANs where you might have, let's say, thousands of computers, and maybe 50 to a 100 printers. Then I can access a printer that is, you know, very physically close to me, so I don't have to maybe take the elevator up ten floors to go to the printer. Any kind of drive on any kind of computer can also be shared, so I can access the files from another computer. There might be limited Internet connectivity, only certain systems have access to the Internet, that can be shared as well. And even software applications can run centrally on a single server, and that can also then be shared with other users.

 

Communication is very Easy in a LAN environment. Typically, all systems use the same address configuration, so everyone can see each other. The protocols typically are very Fast. The network cabling is also very fast, because you aren't dealing with a lot of it. And ultimately, you can just save a lot of time in terms of just being able to access those resources remotely. So you're not physically running around from computer to computer all the time, saving information on flash drives, for example, and then bringing them back to your computer.

 

There are some disadvantages, however. Now, Security in and of itself, it should not be considered a disadvantage. In other words, you can have security in a LAN environment, it's just that it needs to be thoroughly set up, and you need to maintain it regularly, and you need to be fairly vigilant. So unauthorized access can be granted, if it's not set up correctly. The instant two computers are on the same LAN, then there is a way for one computer to access the content of another computer. So you need to ensure that security is implemented correctly.

 

There are typically are distance limitations, and again, generally you'll find the LAN limited to a single building. But it's possible to go between multiple buildings if they are close enough. There are devices that can boost the signal strength so that you can extend the distance a little bit. But once you start getting in to multiple buildings, that generally involves different types of devices and protocols that really aren't designed to work in a LAN environment. In fact, we'll talk about some of those a little bit later. But typically, again, you'll find a LAN relegated to a single building. And there certainly are Setup costs. You need to purchase the Hardware and the Software to ensure that you are able to communicate with all of the other systems.

 

Now, in this presentation, we'll take a look at the wide area network or the WAN and this is effectively the complete opposite of the LAN.

 

WANs are used to transfer data across very large distances. Commonly implemented when you need to connect multiple LANs together. So, if for example, an organization has multiple physical locations that are very geographically separated, we can use a WAN to connect each of those locations.

 

Now, they do use different protocols than LANs including PPP, or point to point protocol, Frame Relay, or ATM which is asynchronous transfer mode. But that depends on what your needs are and we'll come back to that in a moment.

 

[Video description begins] A diagram comparing a LAN to a WAN displays. A LAN made up of desktop PCs and three switches is connected to the cloud via a series of routers. A WAN connects two LANs, each made up of multiple switches and PCs, to the cloud using a series of routers. [Video description ends]

 

But if you compare the two, again, really the main distinction is the area or the size. A LAN is generally relegated to a single building or a very small geographic area. Whereas a WAN can be a very wide geographic area and honestly, there's no real limitation there, it could actually span the globe.

 

And in terms of Ownership, LANs are typically owned by the organization. So, all of the equipment is physically purchased by the organization. Whereas a WAN is generally implemented as a subscription service from some kind of service provider. So that, of course, could be an internet service provider or a telecommunications provider or Telco. They are the ones who already have the infrastructure. It would be prohibitively expensive for most organizations to implement their own WAN technologies. Because we just don't have connections that can span hundreds or thousands of miles. So, we subscribe to the services because the service providers do have that already, so we just pay a monthly fee and use their infrastructure.

 

So, here we just see another example of what it might look like. We have a LAN over on the left-hand side, which again is typically relegated to a single building. We would have all of our client computers, maybe a backbone that connects us through to different floors and gives us access to other services, such as storage or various other servers and routers. But ultimately, all of that is contained within the single LAN. [Video description begins] A diagram of a LAN versus a WAN displays. The presenter points to a section of the diagram that illustrates a LAN. Multiple PCs, a data center, and a server are connected to the building backbone via a series of routers. [Video description ends]

 

Then over on the far-right, we might have a branch office, that's another LAN. [Video description begins] The presenter points to the section of the diagram that illustrates additional access points to the greater network. A branch office consists of a LAN made up of multiple PCs connected to the WAN via a router. [Video description ends] So to connect those two LANs together, we need a WAN. [Video description begins] He points to the center of the diagram, which consists of a cloud service connecting the two LANs together using multiple routers. [Video description ends]

 

We might also have a telecommuter, somebody who works from home or any kind of remote user, someone who just travels a lot. In all of those cases, for full connectivity, the WAN is what allows everyone to connect to anyone. [Video description begins] The telecommuter and remote user link to the network via the WAN. [Video description ends] But again, that is typically some type of service to which we subscribe and just pay a monthly fee.

 

So, coming back to some of those technologies, it is a different type of network, so, there are different types of protocols. There is different hardware that's used and some of them include Integrated Services Digital Networks or ISDN, Switched Multimegabit Data Services or SMDS. Synchronous Optical Network or SONET. Synchronous Data Link Control or SDLC. High-level Data Link Control, or HDLC. Frame Relay, and these days becoming more common, is actually just Ethernet. Now, I'll come back to that in a moment. But most of the other ones are becoming a little bit dated. They're certainly still out there but those are all different types of services with different speeds and performance characteristics and different prices.

 

So, in general, what you would want to do is try to determine how much WAN connectivity you need. In other words, is everybody using the WAN all day long or is it just a few people needing casual access? That can help you try to determine what kind of bandwidth you need and ultimately, choose the best technology for the best price.

 

But again, Ethernet, you might be a little bit surprised to see that because we tend to think of Ethernet as a LAN protocol. But Ethernet in and of itself is just a protocol, meaning that it's just a set of rules for how information is passed. But we also tend to think of Ethernet cable when we see that term. The regular network cable that we are all familiar with. But that cable is not really part of Ethernet, per se. Ethernet runs over twisted pair copper cabling and that cable does have a distance limitation of only 100 meters. But clearly, we would not implement a WAN over a twisted pair copper cable. But again, Ethernet is just a protocol. It can very happily run over fiber-optic cable, which can cover many kilometers. So you can still implement an Ethernet network over large distances. So, this is definitely becoming a lot more common. Just due to the inherent improvements to the Ethernet protocol and speed, such as gigabit per second, or even 10 gigabits per second. Or WAN technologies and that's very much faster than what you might get with some of the older technologies.

 

So then finally, the Advantages and Disadvantages. The primary advantage to the WAN is again, the distance, it can cover a very large geographical area. It allows you to implement Centralized data as well, so that if you do have branch offices, for example, corporate headquarters might be where all the data actually resides. But the branch offices can access it centrally and you can certainly still share software or any other resource across the WAN. And these days, they do offer very high bandwidth, where if you go back maybe 15, 20 years, WAN speeds weren't all that good. So, by today's standards, they certainly are much better.

 

There are still disadvantages because we do now have a mix of different technologies, security can become an issue. As you have to move from one protocol and one physical type of technology to another. That can create what's known as the security gap because certain features just might not be supported by both technologies. And it certainly does involve Setup costs, we need Routers, we need certain types of Switches in some cases. And Security software also has to be implemented while the data is traversing the WAN, so that it's not picked up by anyone on the public Internet. But again, typically, the advantages far outweigh the disadvantages when it comes to implementing a WAN.

 

The next type of network that we'll take a look at is the Personal Area Network or PAN. And this is a relatively new type of network that arose due to the proliferance of devices such as smartphones, tablets, headsets, gaming consoles, remote controls, things that weren't all that common perhaps maybe 10 or 15 years ago.

 

So the PAN refers to an interconnection of these personal devices that are all within range of an individual. [Video description begins] A diagram of a PAN displays. Devices such as a smartphone, headset, laptop, and printer are connected to a desktop PC. [Video description ends] Now that range is typically not very far, usually around ten meters. And PANs are typically wireless networks that allow these devices such as laptops, printers, mobile devices, and such, all to be interconnected with each other.

 

So when it comes to building a PAN, you can do so in a Wired fashion. But it's usually not anything like an Ethernet network, where there are cables for each device that are all plugged in to a central switch. It's usually more so you have a single computer that then connects to multiple devices using things like USB or FireWire. But again, when you consider all the types of devices that are interconnected, this does count as a personal area network even if there isn't any kind of network cabling. But more commonly, you'll see the wireless PAN or WPAN. And this is implemented typically using Bluetooth, or WiFi, or even Infrared. But of course this eliminates any kind of cabling and tends to be again a little more common with today's devices.

 

So some examples of the devices in a PAN include Wireless keyboards, Wireless printers, Wireless mice, Smartphones or tablets, TV remotes, Gaming consoles, and various other Smartphone technologies. So really it doesn't matter what it is, it can be just about any kind of device that would interact with any other device. It might also include health equipment such as Fitbits in a PAN. But really it's any kind of device that interacts with any other device within the same close proximity.

 

So, in terms of Advantages and Disadvantages. On the pro side, we don't require any kind of additional space usually or any kind of wiring for most PANs. Again, the wireless PANs tend to be much more common. And you can connect in numerous devices at once, there's no real limitation in terms of the number of devices. And it's usually very Cost effective because there is almost no infrastructure required. And they are easy to set up, they're reliable, and they usually are fairly secure. Because in most cases you are the only one that would have access to these devices.

 

But on the con side, it does have a Limited range. And again, it's usually around ten meters, which by the way, is the distance that Bluetooth will reliably travel. And it can be susceptible to Interference. Other signals such as radio signals can interfere with communication. And the data transfer, it certainly could be considered slow if you compare it to LAN speeds, for example. But in most cases, it's not that much data. So it doesn't really appear to be all that slow. The speed itself might not be all that high, but it's usually just a small amount of data. So that's usually not too much of a consideration. And again, as in most other scenarios, the advantages tend to outweigh the disadvantages.

 

The next type of network configuration that we'll look at in this presentation is the Metropolitan Area Network or MAN. And quite simply, this falls somewhere in between the Local Area Network or LAN, and Wide Area Network or WAN.

 

It's larger than the LAN, but really not quite as large as a WAN. But typically what you'll see might be a couple of branch offices that are relatively close together. Maybe in two separate buildings in the same city, or even on the same block. But there still is a distance to overcome that really can't be handled by Ethernet. You know, you can't just run an Ethernet cable from one building to another in most cases. [Video description begins] A diagram of a MAN displays. Two networks in separate buildings are connected together. Each network consists of devices such as laptops, servers, smartphones, printers, and routers. [Video description ends] So it's just a small WAN, really is what it comes down to.

 

So with that, the technologies used to connect the two LANs usually are similar to that of a WAN environment. It might use Fiber Distributed Data Interface or FDDI, which might certainly be used to transfer data in a LAN as well. So with this implementation it actually is consistent, you have the same technology in the LAN as the MAN. Or you might see asynchronous transfer mode, or ATM, and that's more commonly used for WAN connectivity. But again, you are still covering distances that can be fairly large.

 

So ATM is better suited for this type of connection. And it is also ideal for audio and video conferencing online. So chances are in between these two branches, you might be implementing that type of connectivity, so that is a very good option. Or Switched Multimegabit Data Services or SMDS, and this is also used to transfer data over large geographical areas. And because it is, as its name indicates, multimegabit, then you typically do get reasonable bandwidth over that distance.

 

Some examples of a MAN, Government agencies, again, they do tend to have multiple buildings fairly close together in the same city. University campuses, in fact, you might even hear the term CAN, which is Campus Area Network. And that's really the same thing, it's just a small WAN is what it comes down to. But there are still multiple physical buildings that can be quite separate. Hospitals, Network of fire stations, Airports, if there are a number of terminals that again, have a fair distance between them. Or Libraries, they often have implementations of metropolitan area networks.

 

Looking at the Advantages and Disadvantages. On the plus side, it certainly can provide better bandwidth. The speed for the connecting links usually tends to be pretty good. Because for starters, they aren't really that far in distance as compared to a full-blown WAN. So what you can often get is a dedicated connection. And of course, this means that you aren't sharing the bandwidth with the rest of the public Internet. So you can get pretty good speed and that of course allows you to very quickly access resources on the shared network no matter where they are. And it can offer a Potential cost savings as well depending on the type of implementation. But you can share resources such as your Internet connection. So in other words, only one location actually has the Internet connection and then the other locations use that. That can result in the cost savings.

 

On the negative side, the Equipment can be expensive. It really is still WAN-based equipment, so if you are looking to implement a dedicated MAN you would have to purchase everything. And this can certainly result in more administrative overhead. You aren't just managing the LAN anymore, but the MAN as well. And this can become difficult to manage if it starts to get too large. But, that's obviously up to you. You can certainly control that and then maybe you look at some WAN technologies at that point. And most implementations do require fiber optic connections to cover the distances that are needed. It still could be several miles or kilometers, so fiber is ideal in this case and that, again, can be expensive and a little difficult to maintain. But ultimately for environments that do have these multiple locations relatively close to one another, then a MAN can certainly be advantageous.

 

In this presentation, we'll talk about the Wireless Mesh Network or WMN and these are created by using a collection of wireless access points.

 

Now, that might not seem all that different from let's say, just your home Wi-Fi. But in that type of scenario, you have devices that are all connecting to a single wireless access point. They can certainly then connect to each other and access the Internet, but it's just a single, centralized access point. If I were to take my laptop for example and connect to my own home Wi-Fi, I certainly have access to any other device that might be connected. But if I then take my laptop and go to my friend's house, that's a completely separate wireless network, so I have to disconnect from mine and connect to theirs.

 

When you have a wireless mesh network, all access points are connected to the same network. So I don't ever have to specifically connect one access point, then disconnect from it and reconnect to a different one if I move around. As long as I remain within range of any access point, I maintain the connection to the network. So the access points are spread out among numerous wireless mesh nodes.

 

So typically where you see this kind of configuration is in very large area, where you still need wireless access. An entire building for example, such as a hotel, no matter where you go in the hotel, you maintain wireless connectivity. Another common example is an airport, anywhere within the terminal you maintain your connection, so all of the nodes communicate with each other and share the network connection.

 

As far as the nodes themselves are concerned, they're basically just small transmitters. And they function the same as wireless routers but as mentioned, they are all part of the same network. But they still use the same WiFi standards 802.11a, b, g, or n, depending on what has been implemented, but it's still Wi-Fi. So it's all the same type of connection.

 

So in terms of Advantages and Disadvantages on the plus side, certainly a Cost savings because there's Less setup required, there's Fewer cables. You just implement each access point and that allows you to spread out the network. Many of the nodes are self-configuring and even self-healing, meaning that all you have to do is really just plug them in. And they configure themselves to access the network automatically and if something fails on the device, they can usually fail over to another device or they can attempt to restart whatever failed. And again, uses the technologies that are already in place, so the 802.11 specifications.

 

On the negative side, they can be Difficult to manage and maintain because the Devices themselves tend to be placed in locations that are difficult to access. Maybe up in the ceiling or even behind some kind of a barrier. So they can be difficult to physically service and it certainly can get expensive if the number of devices grows too large. In other words, we have to keep writing and keep growing. We get more and more access points and more and more devices, certainly the cost can go up.

 

But again, in most cases, the advantages will outweigh the disadvantages. Usually just purely for the ease of connectivity in this type of scenario. Again, just not needing to physically disconnect from one access point and reconnect to another is one of the best advantages.

 

In this presentation, we'll take a look at another very popular high-speed Internet service known as Cable Internet. And this is a fast and reliable technology that you can use to connect your residence to the Internet. Using what we might consider to be standard cable TV cable.

 

Now, this is often referred to as broadband and it's a technology that also is known as Hybrid Fiber-Coaxial or HFC. Now, that would be a more modern implementation. So you may still find certain providers that aren't using fiber. But the hybrid in this case means that the service provider runs fiber optic from their location to essentially the connection point of your house. But from that point, it would be coaxial into your house. So there would be two different types of cable used here. But when they use fiber from their office to your home, that can cover a much greater distance and usually offer much better bandwidth as well. So again, coaxial cables. Again, the standard cable TV cable, are used in the house to run the service from something like the telephone pole into your actual residence.

 

Now, it still uses a specific device, referred to as a cable modem. But the service itself uses, essentially, unused channels of what typically would carry your TV signal. So there's Predefined frequency ranges that are otherwise used for television programming. So you still need to, as opposed to just regular TV channels, but in fact in most cases, if you just took a regular coaxial cable and plugged it into the wall jack where you have the cable modem plugged in. And then plug the TV into the other end, you would still find TV service coming over that line.

 

So the cable modem essentially just focuses in on those frequencies carrying the Internet signal and that's what you get at your computer. So the cable modem still has to be there, and this is typically provided by the provider. So you generally don't have to purchase this. So the coaxial cable, again, comes from your wall and then goes into the modem. That's your incoming service and of course, there's a power connection. And then it is essentially just a standard Ethernet connection to your computer.

 

Now, more modern devices would probably have multiple ports so it acts as a switch as well, and it would probably also be wireless. But this is more so what the original cable modems used to look like. But it's still essentially the same type of configuration.

 

Looking at the pros and cons. On the plus side, this works without a phone line. So you don't need to worry about tying up your phone service when you're using cable Internet. It generally has a very fast connection speed, these days, again, usually faster than DSL. And it can be less restricting in terms of location. Now that's if the provider uses the hybrid fiber-coaxial. If it's pure coaxial all the way from the provider, then you typically are still limited to around three kilometers thereabout. But most of the providers these days are using fiber, so they can greatly extend the distance beyond what DSL can. And it's typically a very reliable service.

 

On the negative side, Cable speeds can be influenced by Bandwidth caps. The provider can just flat out say this is the maximum amount of bandwidth available to you. But that can be based on the tier of your subscription and it is essentially a shared network. So if you have a high volume of users, then you might notice some performance degradation. Although that's less of an issue these days, again, with the fiber backbone. And it can still be Limited availability. In other words, if you're in a very rural area, there may simply be no providers. So you may still have to go with something else beyond cable Internet. But if you do have it in your area, then again these days, it does offer usually very high speeds and a very reliable service.

 

In this presentation, we'll take a look at the basic characteristics of the digital subscriber line or DSL Internet service. And this is a technology for delivering high-bandwidth Internet over regular telephone lines.

 

Now, despite the fact that it uses standard phone lines, it does not compete with the telephone service. In other words, you can still be on the phone when you are online. And this is because it uses higher transmission frequencies to separate the data from the voice signals.

 

Now, in terms of speed, we say it is high speed, but you can expect quite a variance in what you will actually get depending on the provider you choose and the tiers that they offer. But current services these days should offer up to about 10 megabits per second or more, for what you might consider to be a fairly standard service. But there is going to be quite a wide variance there. You might find lower tiers that might only be 3 megabits per second. You might find significantly higher tiers that go as far as 100 megabits per second. So it really depends on what you need, if it's just standard browsing, 10 megabits, for example, would be plenty. But if you're wanting to do a lot of streaming, watching videos and movies then you would probably want something a little higher.

 

[Video description begins] A diagram of the DSL setup displays. The user's system consists of a PC and a DSL modem. It also includes a phone line. The modem connects to the service provider via a DSL Access Multiplexer, or DSLAM. The connection continues from the DSLAM through an ATM network and a router to connect the user to the service provider's DHCP servers and the Internet using PPPoE. [Video description ends]

 

Now looking at the components, of course, it does begin with your PC, which would connect directly through to a DSL modem. Now that would be supplied by the service provider. So you don't have to go out and purchase that. And the phone doesn't really connect through the DSL modem, that really is just to indicate that you can still have your standard phone service. But any phones that you still have, let's say in your house, would still just connect through to a regular wall jack. And they typically do have filters placed on them to ensure that there isn't any intermixing of voice and data. But again, the idea is that you can still have both.

 

Now, that connects through what's called a DSLAM, which is the DSL Access Multiplexer, and you wouldn't have that in your home. That would be just sort of a central connection point that the service provider has that would aggregate all of the connections in one particular area. And then from that point it would travel probably over an ATM network through to the service provider. DHCP servers would be there to give you an IP address. And once you have that, of course, you would be able to access the Internet.

 

Now down below you see IP and the Network Layer. That just means that your system, your PC does get an IP address and it operates like any other Ethernet network at that point. So again, you just get an IP address and you can communicate with the DHCP servers and of course, ultimately the Internet. But the connection between your modem and the service provider uses a service called PPPoE. Now, that's Point to Point Protocol over Ethernet. This operates at the network layer as well, but really what that does is to provide authentication. You initiate a connection from your computer and it asks you for a username and password, that's Point-to-Point Protocol. Over Ethernet is simply the underlying structure. But once you authenticate with a username and password, then that initiates your connection and you can use it as long as you like from that point. And then once you're finished, you can just disconnect and everything shuts down.

 

Now DSL typically comes in two varieties known as asymmetric and symmetric. And for most people who would have this service at home, it would probably be asymmetric or ADSL. And what this means is that there's a variance between the speed of downloads versus uploads. And really, this is what you want in most cases at home. Again, if you have a faster package and you're wanting to download videos or movies, then what you want is most of the speed allocated to downloads. The uploads are really insignificant by comparison, you only make requests to see a website or download a video. So there's very little bandwidth going up the service provider, most of it is down.

 

But if, for example, you have a corporate network and let's say, you do a lot of video conferencing. This needs to be much more symmetric. In this case, you have an equal balance of download to upload because you're transmitting as much information as you are downloading. So you tend to see symmetric DSL, or SDSL much more in a corporate environment as opposed to maybe a home environment. Most service providers will offer either, and there might be some differences in the pricing, but it's generally asymmetric at home, symmetric more so for a business. But even then, it would depend on what you are doing most of the time.

 

In terms of Advantages and Disadvantages, on the plus side it does offer high bandwidth with respect to Internet speeds and it uses existing phone lines. So most places these days, most homes still have the infrastructure in place and it Allows Internet connection and phone line to be used at the same time. Now, it should be noted that's only for ADSL. If you are going with SDSL, the synchronous variety, this actually requires a dedicated line. So in that case you cannot use the phone line at the same time as the service. But again, for most people at home it would be the asynchronous DSL. And the modems are often provided by the service provider, so again, you don't have to purchase anything in most cases.

 

On the downside, performance can suffer the farther you are from the provider. There's a distance limitation of about three miles but the farther away you get, the more the performance tends to suffer. So another way to think about that is the closer you are the better, and of course, it does actually require a landline. Now, as I just mentioned, most people probably still have one, but these days, a lot of people don't. They're just using their cellphone, for example. So if that's the case, you would actually have to pay to get a landline installed and it's limited availability in remote areas. You know, the farther away you get from urban centers, you may not find this service as available.

 

In this presentation we'll take a look at Fiber Optic, which really is the best option these days when it comes to high speed Internet access.

 

The fiber optic lines themselves consist of tiny strands of plastic or glass. And as the name indicates, it uses optical transmission. In other words, pulses of light as opposed to some kind of an electromagnetic current running down a copper wire. So this really is considered the best option for reliability and performance. Most notably because of the speed and the distance it can travel. We are talking about just pulses of light, so they can go much, much farther than electromagnetic signals can over a copper wire. You can be many miles away from the service provider when using fiber.

 

Now not only does it have the better speed and the better distance, but it's also capable of carrying much more data. So it's referred to as a Converged service whereby that single fiber cable can carry Voice for your phone line, Video for your TV, and Data for your Internet, so everything comes in over that one line. And because of the bandwidth capabilities, your TV service can handle hundreds of high definition channels. Which of course represents a lot more data than just standard resolution.

 

So looking at a Speed Comparison here. [Video description begins] A table displays with columns for Technology, Average speed, and High-end speed. The technologies being compared are Fiber, DSL, Cable, and Satellite. [Video description ends] We can see that even at Average speed it's much faster than DSL, cable, or satellite. 50 to 100 Mbps for even what would be considered a low tier. And from one to 10 Gbps on the high end, and again that's much faster than what you'll see with DSL, cable, or satellite.

 

[Video description begins] DSL has an average speed of 768 Kbps to 1.5 Mbps, with a high-end speed of 3 Mbps to 10 Mbps. Cable has an average speed of 4 Mbps to 6 Mbps, with a high-end speed of 10 Mbps to more than 100 Mbps. Satellite has an average speed of 5 Mbps to 10 Mbps, with a high-end speed of 12 Mbps to 25 Mbps. [Video description ends]

 

Now again, there will be some variance in the speeds for DSL, cable, and satellite depending on the tier. But none of them really get anywhere close to what fiber can handle.

 

And finally, looking at the Advantages and Disadvantages. Of course, the primary advantages are speed and distance. You no longer have to be with three miles of the provider. But additionally, fiber optic is pulses of light, so it's not susceptible to Radio or Electrical interference and any kind of copper cabling is. And though it might not seem intuitive, the lines themselves are actually less prone to damage. They're very robustly made and again, as long as a little bit of light can get through, then you can still get your signal. But if a standard copper wire is too close to a heat source for example, then that can also damage it. But heat really does not affect fiber optics either. [Video description begins] Fiber optic cables are less prone to damage from wear and tear. [Video description ends]

 

And there are certainly still disadvantages, it's not available in all areas. I'd say at this point in time, it's maybe no better than 20 to 30% in major North American regions. And it certainly does require all new infrastructure. Now, this cost of course is ultimately absorbed by the service provider. But the service itself from the customer perspective will probably be more expensive than DSL or cable. So that of course they can recoup those costs. But it certainly does provide best speed and the greatest distance.

 

In this presentation, we'll take a look at dial-up and satellite Internet access. And beginning with Dial-Up this is certainly considered by today's standards to be a very old technology. And not only is it old but it's also very slow by today's standards. Dial-up never exceeded 56 kilobits per second, so not even anywhere near the megabit range that we expect today.

 

Now, despite that speed that is sufficient for basic Internet-related tasks such as email and browsing. Although even browsing might be a little bit slow, but since there are so few users using dial-up these days, it's not that bad.

 

Now, in terms of Advantages and Disadvantages, it does still have the advantage of using your existing phone line. So in most cases, all you need is a modem and they would be very inexpensive these days. And it doesn't require any kind of a special line to be installed. So the Internet Service Provider does not have to come and install anything additional. You literally just plug your computer into an existing phone jack. And dial-up accounts can be used anywhere in the world provided there is a phone line. So you do have, essentially, global access.

 

But certainly, when it comes to disadvantages, it really is the slow speeds. There really isn't much that you could do these days on dial-up that we would consider to be adequate where it comes to the speeds and the performance. And it also does tie up the phone line while the Internet is in use. So unlike DSL, that we saw previously, you have to use one or the other when it comes to dial-up.

 

Now another option is Satellite and this of course is a wireless connection that requires three satellite dishes. One attached to your property. One in orbit in space, and One at the Internet service provider. Essentially the one in space is the link between you. Now, you'll probably wouldn't see this in too many urban areas. But if you are very remote, then this really might be your only option. You just might not have any kind of phone line at all. A common example, of course, is for ships at sea or perhaps oil rigs that spend months out at sea at any given time. So anything that is considered extremely remote could certainly use satellite.

 

So for the Advantages and Disadvantages of satellite. On the plus side, it certainly is Faster than dial-up. And you would consider this to be High bandwidth. But again, compared to today's high-speed Internet, I don't think most people would consider it to be particularly fast. It certainly does not require any kind of phone line. And it does provide you with availability in, again, those very remote areas.

 

But it certainly has some disadvantages as well. There can be Poor latency, you literally are transmitting your signals up to a satellite in orbit, so of course that's going to take some time. Weather can affect signal strength, you are again transmitting through the atmosphere. So if you have a lot of clouds, and in particular, a lot of rain, that can affect your signal. And the same goes for obstruction, such as Branches or Buildings that might be in your line of sight.

 

There can also be Bandwidth limitations, in other words, that the service provider might actually implement. In other words, you only have x amount of bandwidth let's say, per month. And once you start to approach that, then they might actually throttle back. So toward the end of the month, things might seem to slow down a little bit and, of course, this can be very expensive. There is a lot of infrastructure required and of course, it's not very cheap to get satellites out into space. So the service is much more expensive. And when you compare that to the speed that you actually get, it really isn't worth it at all if you have something like any kind of land-based high-speed Internet access available to you. But again, in some cases it's really the only option because you just might be so remote.

 

Now, in this presentation, we'll take a look at Integrated Services Digital Network, or ISDN. And this is a Set of communication standards for digital telephone connections.

 

Now, before going any farther, if we go back quite a ways, before any kind of Internet access, and we just think about the standard telephone service. At that point is was not digital, it was an analog connection, you just made a phone call over an analog line. But of course as technology improved, we realized that in fact we could use digital packets to transmit telephone or voice information. So now that we could digitize voice communications, well, we could also transmit data because, of course, it's just digital. So this was Originally designed to run on digital telephone systems already in use but now we could add data to this.

 

So, prior to ISDN, it was not possible to use regular telephone systems, or any kind of fast transportation. We didn't have any means to digitize the data and implement it as what we consider to be a data network. Now overall ISDN is actually quite old. I doubt you'll find much of it in use today, but it was very common when it came out and did offer higher speeds than services such as dial-up.

 

Now ultimately, it is implemented as a circuit-switched telephone network system. And this is important to take note of, circuit-switched versus packet-switched. At the end of the day, a circuit-switched network really is what we would consider to be a regular phone network. And I've mentioned this before but, again, if you think about old movies or TV shows where you saw the telephone operator in front of a switchboard. They were literally running patch cables between the source caller and the destination caller, that completed a circuit. And that is a physical pathway, you connected one wire to another, if you will, implementing a physical pathway.

 

Now that does not happen in packet-switched networks. It's all done virtually within the inter-networking equipment and there's no dedicated path that a packet actually must follow. It can go in different paths at different times, if it deems that that's a better option. But because we are dealing with digital communications, it did allow now for packets to be implemented on this network. So it allows access to packet-switched networks. So in other words, our internal networks on our LAN can now use what was traditionally a phone network that is circuit-switched to be used as a packet-switch network.

 

Now, this has largely been replaced by broadband Internet in recent years. So as I mentioned, I don't think you'll find very much ISDN these days. But there might still be a few specific configurations where maybe it's just a legacy implementation that's still being used for a particular purpose. But in general I don't think you'll find it much anymore. And one other aspect of it is that you did need specific hardware. Because we are translating, if you will, packet switched network data into circuit-switched network.

 

So you can see in the graphic, there was an ISDN bridge. And this handled all of the translation, if you will, and they needed to be on both sides. [Video description begins] A diagram of an ISDN setup displays. A group of LAN PCs are connected to a hub, which in turn connects to an ISDN Bridge and a telephone. This connection accesses the ISDN network over the phone lines to connect to another ISDN bridge, which allows access to another group of LAN PCs connected via a second hub. [Video description ends] So typically, if it was just something that you were implementing, let's say, between two branch offices or your headquarters and a branch office, then you had to set this up on both sides.

 

Now, there are two main types of ISDN connections. BRI, which is Basic Rate Interface, and PRI, which is Primary Rate Interface. [Video description begins] A diagram displays three types of cables: BRI, T1-PRI, and E1-PRI. BRI has two B channels and a D channel; T1-PRI, used in North America and Japan, has 23 B channels and a D channel; and E1-PRI, used in Europe, has 30 B channels and a D channel. [Video description ends] And as its name indicates, Basic Rate Interface was a lower tier of service providing only basic needs but did have a lower cost. Primary was a better connection, more reliable, and had much faster speeds.

 

Now, the reason for this is with basic you had what was known as two bearer channels, and essentially they carried your data. And each one of those was 64 kilobits per second, so with two of them you could have a 128. The D channel, despite the fact that it stands for data, was data signalling and it really didn't carry any data. it was just the timing, the format, if you will, of communications. So that everything could be synchronized, and effectively again, it really did not carry any actual data. So you got your bandwidth from the B channels, the bearer channels. So with BRI sometimes you might have heard it referred to as 2B + D.

 

Now, the primary rate interface options came in two varieties, T1 and E1. T1 was implemented mostly in North America and Japan, and E1 mostly used in Europe. But what you see here is that we have many more bearer channels. There were 23 for T1 and 30 for E1. So both of those were significantly faster than BRI. T1 was usually about 1.5 megabits per second, and E1 up around 2. But, of course they were also more expensive.

 

So then looking at the pros and cons. On the plus side you did have Multiple digital channels available to you to improve your transfer rates. And they were always consistent, because all of these were governed by a worldwide set of standards. So you always knew what you were going to get when you subscribed to ISDN services. And they were competitively priced, again, compared to other options at the time.

 

But on the downside, it was costly compared to other telephone systems. Though, if you're just needing a digital telephone system, then you could probably implement this a little more cheaply. And again, it does require specialized digital devices. But they would be provided usually by the telco or the service provider. So again, you didn't usually have to go buy them yourself, but you certainly still had to pay for them monthly through your subscription.

 

In this presentation, we'll talk about a feature of networking known as Line-of-Sight, or LOS. And I should mention that in some cases you may hear LOS referred to as loss of signal. But in this case, line of sight is quite simply The path between two antennas. And it is certainly something that is important to consider when designing an outdoor wireless network. In other words, is there quite simply something in the way? Is there an obstruction of some kind or do you have a clear path for those wireless signals to travel?

 

Now, there are degrees, if you will, when it comes to line of sight. And the first option is flat out complete line of sight. In other words, there are no obstacles between the two antennas. So, you can transmit a signal very clearly from point A to point B without anything getting in the way. [Video description begins] A line of sight diagram displays. Two antennas broadcast signals to each other. Both are tall enough to pass the signal over various buildings. A section in the center of the signal is labeled the Fresnel zone. [Video description ends]

 

Now the Fresnel zone that you see indicated by the diagram, refers to really just the area in between. But it really just is an area where you might find the phenomenon of electromagnetic signals still experiencing some kind of interference. Let's imagine that the building in the middle is not really directly in the way. But let's say close by and let's imagine that there is a lot of glass and a lot of steel in that building, that can still affect the transmissions. They might bounce off the glass and they may even be bent a little bit if you will by the heavy amounts of steel that can cause a magnetic field. So it's that area of possible interference. So as long as there really is nothing getting into the Fresnel zone then you can consider that to be complete line of sight. You really should have pretty good communications.

 

Near Line of Sight may include partial obstructions between the two antennas. [Video description begins] A near line of sight, or nLOS, diagram displays. Two antennas broadcast signals to each other. Both are tall enough to pass the signal over various buildings, however, one of the buildings is tall enough to intrude into the Fresnel zone. [Video description ends]

 

If however we have full obstructions in the Fresnel zone. The buildings reach well into that zone to the point where they really are blocking the signal, then this is referred to as Non Line of Sight or NLOS. And it's quite likely that you would encounter a lot of connectivity problems in that case. [Video description begins] A non line of sight diagram displays. The signal passing between the two antennas is blocked by multiple buildings protruding into and through the Fresnel zone. [Video description ends]

 

Now, the implementation of this type of communication is not particularly common. But perhaps in a fairly large city, you might have an office in one building, and an office in another building that's fairly far away. In which case, to connect those two, using a wireless connection certainly is feasible. But this is where the line of sight comes into play. And quite honestly, can you see from one to the other or is there something in your way? And if there is then wireless probably is not going to be a good option. But if you do have that clear line of sight then this probably will work to suit your connectivity needs.

 

These days, of course, mobile phones are more prevalent than ever, so in this presentation, we'll take a look at Cellular Networks. Which are simply the networks over which our mobile phones can operate. So they're often referred to these days as mobile networks. But the term cellular persists, really, because of the way it's laid out, the network is quite literally divided up into cells.

 

So what you have is a single antenna within each cell, and the cell ultimately is the area that can be covered by that particular tower. Then there's another tower that just has to overlap a little bit with the first one, and so on for every other tower. And this allows us to cover a very large geographic area as efficiently as possible, as opposed to just trying to have a single gigantic high-powered tower that covers the entire area. The farther you get, of course, the worse your signal would be, so this is certainly more efficient.

 

Now the neighboring cells to any other cell, typically, will operate at a different frequency. But an access method known as FDMA, which is frequency division multiple access, allows devices to select the strongest frequency. So, particularly if you're right around the border, let's say, between two cells, it will try to pick up on whichever frequency is stronger so that it can communicate as effectively as possible.

 

Now, of course, there are many users using the same cellular network at the same time. So we also need a way for all of us to be able to do that while not interfering with each other. And one method is known as CDMA, or Code Division Multiple Access. This allows us all to send data over the same frequency by having a code assigned to each transmitter. The signals then spread over a range of frequencies using a pseudorandom pattern, but The signal for each user is modulated by their unique code. So my code essentially controls the signal of my device, and it's separate from yours and every other one. So this way, it's able to distinguish my signals from yours, and we can all access the same network at the same time.

 

Now, there is another access method known as TDMA, or Time Division Multiple Access, that does allow a channel access method so that we can share a channel without interference and multiple stations can use and share the same transmission channel at the same time, because the signals are divided up into different time slots.

 

Now, that does not mean that you can only use your device, let's say, at a specific time of day. Obviously, we can all use them 24/7. But in terms of accessing the channel, your signals to have a little bit of time, then someone else gets a little bit of time, then someone else gets a little bit of time, and they all have to be synchronized. So we get these little time slots. But the synchronization and the timing of the signals presented a challenge because, of course, these are mobile users. So, as you moved, your distance changed, and that resulted in signal arriving at a different time. So this was difficult to manage.

 

So TDMA was largely implemented back in the 2G or second generation mobile networks, and has largely been superseded by CDMA these days. So I don’t think you’ll find too many TDMA networks still in use.