دایره المعارف تاسیسات برق (اطلاعات عمومی برق)
Home Network Wiring and Setup - Chapter 2
Configuring the Hardware
So what do you need and how do you hook everything up? Here are examples of several setups.
Basic Network with 1 Hub or Switch -
This is about as simple a configuration as you can get. With this you can have all of your PC networked together and enjoy all of the benefits that affords you. In the next page 'Home Network Wiring and Setup - Chapter 3' I'll briefly describe Hubs and Switches and the Uplink port.
Basic Network with 2 Hubs or Switches -
This is still a pretty basic configuration. It shows how to use multiple Hubs or Switches to give you more ports.
Network with Broadband at the CWP and 2 Hubs or Switches -
This configuration adds Broadband access. If you have broadband access in any form such as high speed cable, DSL or whatever you'll need some form of Broadband Modem. Most of these modems come as a stand alone device or as a plug-in PC card. For a networked home the stand alone device makes the most logical configuration because it will operate independently of any one PC. Locate this broadband modem at the CWP. Now there are MANY manufacturers of these Hubs, Switches and Modem devices and they will likely label their input/output connections differently than I have in these drawings. These drawings just show a generic configuration.
Network with Broadband at the CWP and a Router/Switch and 2 Hubs or
This configuration adds an ALL IMPORTANT Broadband Router/Switch to your Broadband access. This Broadband Router/Switch adds an important security feature to your network - a Hardware Firewall. This Router will also allow several of your PC's to share one IP address. Without a Router most ISP's will charge you extra for each PC that is sharing their broadband access. The router will allow you to avoid these extra charges. If you have broadband access - GET A ROUTER! They are easy to hookup and are relatively cheap (around $100) and getting cheaper.
If you want to network JUST TWO PC's together you can simply connect the ethernet ports on both PC directly together with a ethernet crossover cable. But, if you want to network three or more devices then you need some type of network distribution device. The simplest of these is a hub. Hubs have 4 or 8 or more ethernet ports. When a packet ( ethernet communicates by sending and receiving short messages called packets) comes into any port on a hub the packet is buffered and sent out to EVERY port the hub has. With a hub every PC will receive every packet that any of the other PC's send.
Links to more detailed descriptions of hubs are:
HowStuffWorks.com - How LAN Switches Work - http://www.howstuffworks.com/lan-switch.htm
Switches work in a similar fashion with one key difference. A switch will examine a packet as it comes in and will ONLY pass the packet on to the port that has the device the packet was intended for. A switch will 'learn' the addresses of the devices connected to it so that it knows what port the packet need to go to.
With a hub every port carries every packet that any device sends while on a switch a port only carries traffic intended for the device connected to it. Hubs do not allow multiple devices to communicate at the same time but switches do. With a switch a device on port 1 can be communicating with a device on port 2 at the SAME TIME as another device on port 3 is communicating with a device on port 4. Switches make much more efficient use of a ports bandwidth.
Switches also allow Full Duplex communications. With Full Duplex a port can transmit and receive at the same time.
Links to more detailed descriptions of switches are:
HowStuffWorks.com - How LAN Switches Work - http://www.howstuffworks.com/lan-switch.htm
Routers are a lot like switches in that they route packets to proper destination. The come in a lot of different forms but for a home network they usually have the additional task of acting as a bridge between your LAN (Local Area Network) and the WAN (the internet). A router will examine packets and determine if they are destined for your LAN or the WAN and route them accordingly. With a router sitting in-between your LAN and the internet and deciding which packets are allowed to flow between the two, it is in an ideal position to protect the two from each other. This is why most home networking routers have built in firewalls.
Routers have one other huge benefit for people with networked PC that want to share a single internet connection. All your ISP (Internet Service Provider) will see is the router and not the multiple PC behind the router that are sharing the one connection. Without a router the ISP will see each PC and the IP address that each PC has. ISP's usually charge extra for more than one IP address. But, with the router, all the ISP will see is the IP address of the router and the router will make sure that packets to and from the internet get to the proper PC.
Links to more detailed descriptions of routers are
How Stuff Works - Routers - http://www.howstuffworks.com/router.htm
A print server is a device that links a printer to a network so that any device on the network can use it. There are two basic way to share a printer among devices that are networked together. The cheapest is to connect the printer physically to one of the networked PC's and then on that PC set the printer up as a shared resource. More on how to do that is coming soon. After this shared resource is setup in the operating system, any of the networked PC's can print to the printer. One drawback to doing it this way is the PC that the printer is connected to needs to be turned on and running anytime another PC needs the printer. In other works, a PC is acting as an expensive print server. The other way of doing it is with a dedicated print server. A print server can be as small as a deck of cards and has at least one printer port and one ethernet port. Print servers for a home network can cost as little as $40 and as much as $200. Mine is a Linksys EFSP42 and has a 4 port ethernet switch and a print server for two printers and cost $130. A print server is a relatively simple device with no hard drive or cooling fan to wear out so you can leave it powered up all the time ready to serve it's printer(s) on the network . The print server costs extra but it eliminates the need for a PC to be up and running around the clock acting as a print server. Nice to have one of these.
UPLINK Ports -vs- Crossover Cables
You'll notice the drawings on the previous page show ports called UPLINK ports. To understand the purpose of an UPLINK port you need to have a basic understanding of the two types of networked devices. You have NDD (Network Distribution Devices - I made that term up) and you have NU (Network Users - again, a term that I made up). An NDD will be a distribution device like a hub or switch. A NU will be a PC or a print server or a router or a broadband modem. So here is the rule of thumb:
When connecting a NDD to an NU - use a standard straight through cable.
When connecting like devices such as a hub to a hub or a PC to a PC - use a crossover cable.
A NDD (Network Distribution Device) such as a hub or a switch in intended to be connected to a NU (Network User) such as a PC. If you connect LIKE devices you have to use a crossover cable. A crossover cable is the same as a straight through cable except the the TX (Transmit) and RX (Receive) pairs are reversed or swapped on ONE end of the cable.
To a network beginner it may not always be clear when you can use a standard cable and when you need a crossover cable. Basically you need a crossover cable when connecting LIKE devices together.
Most manufacturers of hubs and switches know that users will often connect these NDD devices together to add additional ports to a network. With these being LIKE devices a crossover cable is needed. With this in mind, on MOST hubs and switches, one of the ports can usually be configured as an UPLINK port. An UPLINK port has the TX and RX pairs reversed internally to the device which eliminates the need for a crossover cable. Some devices will have an electrical switch near the port that will change the port to a standard port or an UPLINK port. Other devices will have two jacks for one of the ports with one jack wired as a standard port and the other as an uplink port. When your shopping for a hub or switch look for one that has a configurable UPLINK port!
If you must use a crossover cable you can buy them or make them. I have seen 40-11 different descriptions of how a crossover cable is wired. All of them seemed to confuse me so I created my own 40-12th description as shown in the drawings below. To state it as simply as I can - A crossover cable differs from a straight through cable by exchanging or swapping the TX and RX pairs on ONE end of the cable.
The thing that adds to the confusion here, I think, is the fact that there are two wire color patterns - T568A and T568B. As I have said earlier in this website - the meat of the matter is that these two different looking wiring standards are ELECTRICALLY BOTH THE SAME IF you use the SAME color pattern on BOTH ends of a given cable! Irregardless of which of the two color pattern you choose pin 1 on one end is connected to pin 1 on the other end. Pin 2 on one end is connected to pin 2 on the other end and so forth. The difference is just in the COLOR of the wires.
Another way to describe a crossover cable is that one side is wired to the T568A color code and the other side s wired to the T568B color code.
So rather than explain all this in words I have made drawings of the 4 possible cable configurations. You have two wire color standards and you can have a straight through and a crossover version of each. All 4 are shown below:
- Use a crossover cable to connect LIKE devices. For un-like devices use a straight through cable.
- To make a crossover cable you reverse the TX and RX pairs on ONE end of the cable.
- When your connecting a hub to a hub or a switch to a switch - you don't have to use crossover cables if the hub or switch has an UPLINK port. Simplify things by choosing devices that have UPLINK ports!!
- When your connecting a hub to a hub or a switch to a switch using an uplink port, connect one end of a straight through cable to an UPLINK port and the other end of the cable to a standard port. Remember - you are essentially swapping the TX and RX pairs on ONE end of the cable only. This is why you connect one end of the cable to an uplink port and the other end to a standard port.
- Another thing. If you make or buy a crossover cable it will look a LOT like a straight through cable. Make sure you label a cable clearly as being a crossover cable. You can spend hours troubleshooting a problem that arises because you used the wrong kind of cable.
Wireless Chapter 1
Even though this website is all about Wiring, a Wireless Network can enhance your Structured Wiring System a great deal. In fact, as I'll demonstrate here, having a well planned Structured Wiring system will enhance the performance of a Wireless network.
There are two types of wireless network that are available for home networking - 802.11b and 802.11a. A third type, 802.11g is on the way.
802.11a - is 54 Mbps (Million bits per second) network that is relatively new but is commercially available now. It is quite a bit more expensive though. 802.11a operates on a 5GHz frequency band that is less likely to be interfered with by commonly used household items.
802.11b - is a 11 Mbps network that is in widespread used now and prices for the hardware are dropping quickly. Some manufacturers have now adapted modulation techniques that achieve a 22 Mbps speed. D-Link for one has 22 Mbps hardware available which is what I have added to my Structured Wiring system. 802.11b operates in a 2.4 GHz band that is also used by 2.4 GHz cordless phones commonly used in the home. Microwave ovens also use this band. There is a lot of concern about interference interference between these devices. I have a 2.4 GHz phone and I can sit at my laptop with an 802.11b card in place and operating while talking on the cordless at the same with no real interference problems to date. In actual use 802.11 will connect at rates in the area of 3.5 Mbps to 4.5 Mbps. Reviews on the D-Link 22 Mbps system I bought achieved connect rates around 6.5 Mbps. These rates are only achieved when the RF (Radio Frequency) signal levels are the strongest and under the best conditions. When signal levels drop so do the connect speeds.
Wireless speeds cannot come near the 100 Mbps fast ethernet that my Structured Wiring system supports. Wireless, being wireless, does has some substantial advantages but does have some severe limitations. Security is also a major concern for wireless networks. With a range of 300 ft and more, your neighbors and anybody outside your home can pick up your signal.
802.11g - Is a 3rd type. It will operate at a much higher rate of 54Mbps and at 2.4GHz. As you might expect this equipment will initially be more expensive but will drop quickly as it becomes more popular. I believe this standard has the most potential to be the most popular standard in the not too distant future.
Wireless Networking Basics
You basically have two types of
wireless network devices:
Wireless Network Adapters (WNA)
Access Points (AP)
Wireless Network Adapters (WNA)
WNA's are devices that generally attach to a PC. These WNA's can attach to a PC in several form:
PCI Card slot - usually used on a desktop PC.
PCMCIA Cards - usually used on a laptop PC
USB Adapter - can be attached to any PC
Compact Flash Card - usually used on handhelds such as Palm Pilots and Palm PC's.
Access Points (AP)
AP's are usually standalone
'boxes' that attach or bridge your wireless network to your wired network via an ethernet
cable. AP are also available simply as an AP or can be combined with a
hub, a switch or a broadband route and even come as an AP with Router
and multi-port switch. Shown below is a typical AP with router and 4
port switch. AP can even include a Print Server.
You can attach a WNA to your pc but now you need something for it to link wirelessly to. WNA's can link to another WNA or they can link to an AP. In the Ad-hoc mode WNA's can link to another WNA. In the Infrastructure mode a WNA will link to an AP. There are other websites that go into this in more detail than I will here and I'll have links to some of these website on my Links page. One particularly good website is at Home Net Help and Small Net Builder.
The most common configuration for a home network is to have an AP and one or more WNA's. This is the configuration that I'll focus on here. I'll go one step further here and say that the most ideal configuration for a combination of wired and wireless networks is to use a simple AP and NOT to use an AP combined with a router/switch combination. I'll explain why.
The wired network system has the tremendous advantage of MUCH higher speeds and far fewer security concerns. A wired ethernet system operates at 100Mbps -vs- the 3 to 5Mbps that you end up with in an 802.11b network. The security of today's 802.11b has been widely criticized as being highly vulnerable. Worst yet most wireless systems will come from the factory with ALL of their security features DISABLED. It then becomes your responsibility to learn about these security features and figure out how to enable them.
I am not slamming wireless systems here. I have added an AP and a WNA to my own structured wiring system. You just need to know the limitations the wireless links have and how to enable the feeble security features it does have.
Placement of the AP (Access Point)
All wireless Network components utilize radio frequency transmitters and receivers. RF (Radio Frequency) signals are what link wireless components. RF can penetrate wall and floors but in doing so will loose some of its signal strength. With today's wireless systems you'll get the highest connect speeds ONLY with high signal levels. When the signal levels drop lower so do the connect speeds. Because of this it is to your advantage to locate the AP in a place that optimizes exposure to the WNA's. Ideally the best exposure is Line Of Sight. In reality most practical indoor networks will have some obstructions between wireless components. The fewer walls and floors in the wireless signal path the better. The point here is to MINIMIZE these obstructions.
Here is where having a well planned Structured Wiring system will enhance the performance of a Wireless network. An AP is the link or bridge between your wireless and wired network. So when you chose a location for your AP based on the best exposure to the WNA's you'll need to have a wired ethernet port available at this AP location that you chose. Here is another HUGE advantage of a well planned structured Wiring system. You are more likely to have a wired ethernet port already available at this location that you just selected for your AP. For this discussion I'll assume you already have a good Structured Wiring system in place or better yet, you are in the planning stages of creating one.
Look for example at my homes floorplan shown below.
BLUE - CWP
RED - Wired Ethernet Ports
GREEN - Wireless Signal Paths
As a general rule I have as many of my network components located at the CWP as possible. But the CWP is NOT the optimal location for an AP in term of exposure to the possible WNA location that I'll want to use. At least in my particular home layout. You can see this in the drawing above. I have drawn in some green lines from the CWP to some of the locations where I am likely to want to use my laptop with a WNA. I did this to see what kind of obstructions the wireless signal would encounter going to/from the WNA and AP. For example the wireless signal has to pass through FIVE walls on the way to the Master Bedroom. So, my CWP is NOT a very good location for the AP. It is for this reason that I stated earlier that the most ideal configuration for a combination of wired and wireless network is to use a simple AP and not to use an AP combined with a router/switch combination. In order to take advantage of the router and switch features available in a lot of AP the AP NEEDS to be located at the CWP.
Instead, I want to put the AP where I'll get the best exposure to the WNA's.
BLUE - CWP
RED - Wired Ethernet Ports
GREEN - Wireless Signal Paths
As shown in the figure directly above a more optimal location for the AP would be near the wired ethernet port named LVR2 in the Living Room. (You see I'm single so I can put my AP in the Living room.) You can see how from this location that the wireless signal has to pass through FEWER walls. With a well planned Structured Wiring system you are more likely to have a wired ethernet outlet near the place where you decide is an optimal location for the AP !!!
How To Integrate Wireless Into a Wired Network - The Hardware Side
A simple AP can simply be connected to any open ethernet port in your network. That is all there is to it from a hardware standpoint. See the figure below.
If you have an AP with a router and want to make use of the router then things are just a bit more involved. Here is how a wireless AP with a router needs to connect to your wired network.
So, if your going to place this type of AP with Router in location away from your CWP you'll need to have not ONE but TWO ethernet cables running from the CWP to the AP. With my Structured Wiring system all of my outlet plates already have two ethernet ports. So the people who have called my Structured Wiring system 'overkill' can go jump off a tall bridge because this system has once again saved my %#$. All I have to do at the CWP to make this work is unplug the ethernet cable that is now designated as the WAN cable from the 8-port switch it was going to and move it to the WAN port on the broadband modem. The versatility and reconfigurability of this kind of Structured Wiring system is JUST GREAT!!!
Now, for some reason, AP with routers and switches seem to be cheaper then Simple AP's. If you really wanted JUST a simple AP but ended up buying an AP with a router, you CAN disable the router portion and still use it as a simple AP. This way you won't need the extra ethernet WAN cable. This is exactly what I did when I added the wireless network to my Structured Wiring system. I bought an AP with router and 4 port switch ( D-Link DI-614+ ), disabled the router portion and wired it in as a simple AP. More on how to do this in the following section.
I plan to draw more examples showing how to connect different types of wired and wireless networks configurations. This will be coming soon.
How To Integrate Wireless Into a Wired Network - The Software Side
If your just using a plain old AP there is no configuration required for most AP's. They generally work right out of the box. You will need to configure the AP when you enable the security features though. More on that in a minute. On the WNA side there will be configuration that needs to be done. Follow the directions from the supplier of your WNA because they (hopefully) know better than I . Basically the WNA installation involves loading and configuring some sort of wireless signal monitoring software and installing your protocols and services and shares, etc...
Of COURSE the standard installed configuration of MOST wireless systems has ALL the security featured disabled!!!
If you have an AP with a router and want to use it as a simple AP then all you have to do is disable DHCP on the AP. Simple, but the manufacturer of the AP may not make this obvious to you.
If you have an AP with a router and do want to make use of the router then your best to follow the manufactures direction on how to configure the router.
How To Enable The Wireless Networks Feeble Security Features.
As feeble as they are you REALLY SHOULD enable these security features. They will make your network MORE secure. I'll hit the highlight on how to do this but your installation manual should give you more details.
- First, go to the manufacturers website an make sure that you have the latest drivers and software updates. Update ALL your software and firmware but you're better off to do this updating AFTER you get things installed and working.
- Change the default SSID (Service Set IDentifier) to something different. The SSID can be assigned by you using guidelines similar to what you would use for assigning a password. You have to configure the SAME SSID into BOTH the AP and the WNA. This presents a bit of a dilemma for you because as soon as you change the SSID on one of the two devices the wireless part of the network will cease to connect because the SSID's on both sides will be different!!! To avoid this being a big problem, change the SSID on the AP FIRST. Then chance the SSID on the WNA to match the AP. Better yet is to have an ethernet link to the AP which can be used on another PC to configure the AP. PLEASE READ YOUR MANUAL FOR DETAILS!!! IM JUST PRESENTING AN OVERVIEW HERE!
- Enable WEP (Wired Equivalency Privacy algorithm). Along with enabling WEP you'll need to chose between 64 bit, 128 bit or 256 bit WEP encryption and you'll need to specify some sort of 'paraphrase' for the encryption key or keys. The number of encryption bit available may vary from one model to the next. The larger the number of encryption bits the higher the security. A higher number of encryption bits theoretically will lower your connect speeds but most test reviews that I have read seem to disagree on weather this is really noticeable. So, you'd be wise to select a higher number of WEP encryption bits. You'll have the same dilemma as you had changing SSID - the wireless network will not connect when the settings on both sides don't match. So change the WEP settings on the AP FIRST. Then change the WNA to the SAME settings as the AP. PLEASE READ YOUR MANUAL FOR DETAILS!!!
- Disable the broadcasting of the SSID. PLEASE READ YOUR MANUAL FOR DETAILS!!!
- Disable the Remote Administrator option. PLEASE READ YOUR MANUAL FOR DETAILS!!!
جذابیت های برق
در ستایش معماری
تکنیک های نورپردازی، مهندسی روشنایی
فکر اقتصادی، کارآفرینی
تکنولوژی های روز دنیا
504 لغت آیلتس IELTS(ضروری برای همه دانشجویان)
شرط پیشرفت+مدیریت زمان و انرژی
اطلاعات علمی ساده و خلاصه
خلاقیت های ناب ناب
کافه کتاب،فرهنگ و ادبیات
رسانه (ایران، بین الملل)
خنده های رنگی رنگی
دیدنی های تو دل برو
دیالوگ های ماندگار
وقایع و تصاویر تاریخی جذاب، گردشگری
ویرایش نشده ها
معرفی نویسنده و مدیر وبلاگ