CompTIA Network+ Certification (2005 Objectives) Tutorials
Basic Networking / Physical Topologies
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Subtitles of the Movie (CompTIA Network+ Certification (2005 Objectives) / Basic Networking / Physical Topologies)
Physical topologies describe how your network looks once its all put together and is laid out. In this section we will cover each of the physical topologies and discuss some of the benefits and drawbacks that each of them hold. Our first physical topology is the physical bus. Now a funny way to remember this, if you imagine the terminators as being wheels and each of the computers being people on the bus that makes it easy for you to recognize this when you see it. Now when you actually walk up to a physical bus network you will notice that each of the computers has their own connection to the same network cable as each of the other computers. You also notice these T's over here and they stand for termination. Termination is definitely a big deal on your physical bus topology because you can imagine your physical bus being like a pipe with a marble in it. If that marble is our data and we wear to tilt the pipe in either direction the marble would allow and we would lose our data. With the terminators in place with the caps at the end of our pipe that data will stay in its place and not move outside the network. One of the major advantages of the physical bus topology is the back in its deck because this is very old technology. It was the only thing available to us. So we are pretty much stucked with it. As technology has increased we have moved beyond the physical bus topology and the copper media where it relays on. One of the major draw backs of the physical bus topology is it if any one of the computers or any piece of cable failed they would cause the entire network to go down, because that would then be an open part of the media that is not terminating. Another major disadvantage of the physical bus topology is how difficult it was to create a bus network. You actually have to take this primitive things called vampire tab and put a spike into the copper media and hope that you get the copper core to establish the connectivity. Those are very primitive method and we don't only use this so much any more. Let's take a look at the physical star topology and this is a very common topology used today and the reason it is so common is because it is very simple to setup. It simply gets yourself a central connecting device such a hub, router or switch and connects all of your computers to that device. Your computers will then be able to talk. Now of course it is not always quite that simple. Well one of the major benefits of this physical topology is it if one computer failed the rest of the computers would be unaffected other than if they were trying to connect to the failed computer. One of the major disadvantages of the physical star topology is that central connecting device. If they are going to fail we will lose our entire network. In network terms this is called a central point failure and is generally a bad idea. But since our technology has got so good the reliability of the central connecting devices has become very high. So we don't worry about them failing quite as much as we did in the past. Next is the physical ring topology. This is another older technology and it's going to make in a come back today in a different form. The physical ring topology basically has a connector on each computer that loops to the next computer and your data has to complete the circle or you lose connectivity. Now one of the big drawbacks of the physical ring topology is to be a very low data transfer rate. Now we will recommend that problem now but will still face with the fundamental problem of losing any connection or any computer in a physical ring topology. If any one of these wires or any one of these computers is going to fail the entire network would go down. But again as our technology has increased this topology has become very effective in other forms. The physical mesh topology is probably one of the most reliable topologies that we as network administrators have access to. The major benefit to a physical mesh topology is its ability to handle failure or fault tolerance. If one computer fails the other computers will have a mode of connecting to each other. If any lines fail the computers will still be able to go to each other to talk to the other computers. There is one fundamental problem with this. Right now we only have four computers which mean we would have to have three network cards and three cables coming out of the back of each of these computers. That seems too bad, but if you multiply that times 2000 and let us say for example if we had 6000 computers we would have to have 5999 network cards and that many cables as well. So obviously for management and cost reasons we don't use the physical mesh topology in our network environment today. A final physical topology is the hybrid topology and is probably going to be which will run into the most. In this example we see a physical bus connected through a central connecting device to other computers that are considered to be in a physical star topology. So we can combine any of our physical topologies to create a hybrid topology. So this should give you a pretty good idea of our physical topologies look once your network is put together. Next we cover logical topologies.
Tutorial Information
| Course: | CompTIA Network+ Certification (2005 Objectives) |
| Author: | Brad Causey |
| SKU: | 33608 |
| ISBN: | 1-932808-53-1 |
| Release Date: | 2005-03-22 |
| Duration: | 7 hrs / 97 lessons |
| Captions: | No |
| Compatibility: |
Vista/XP/2000, OS X, Linux QuickTime 7, Flash 8 |
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