Posts Tagged ‘Network’
Do you have VoIP problems on a wireless network?
Do you experience a call quality decrease using VoIP on a wireless multihop network? This may be caused if you are sharing that network with Transmission Control Protocol data. Transmission Control Protocol (TCP) was designed for wired networks. By design after a slow start TCP exponentially increases its bandwidth consumption which in turn causes congestion for extended periods of time. This method of data delivery, in large segments or bursts, can affect other data on the network. Voice over internet protocol (VoIP) on the other hand has very specific delivery requirements. VoIP produces steady uniform traffic and depends on the regularity of a network with minimal loss rate. Therefore, when VoIP shares the network with TCP data the outcome is either a reduction in TCP capacity or significantly affected voice quality. This problem occurs solely on the wireless networks, because wired networks have mechanisms in place to provide for the quality of service necessary.
How do we solve this problem? There are many enhancement options that are proposed to solve this problem such as Vegas, Westwood, CUBIC and C-TCP. These options all take slightly different views of solving the problem they: track and adjust in expectation of congestion; monitor and estimate bandwidth needs, and control traffic flow by maximizing slow times and hold back during high output to prevent congestion. It is also possible to separate TCP and VoIP by minimizing TCP at the gateway. However, there is no one “fix all” cure to the problem. It may be that since the wireless network options were not conceived, from the beginning, to address this type of problem we may have to wait until the next generation of wireless networks before it will be full proof.
Wireless Network Card Troubleshooting: Computer Crashes
As the technology advances, now many devices can support hot plug, such as USB devices and 1394 devices. However, essentially, most hardware operations should be completed after the power supply is cut off, otherwise it may cause computer crashes or even the permanent damage to the hardware.
Sometimes computer may go dead if the wireless network card is pulled out suddenly from its related port. This failure occurs in a relatively high frequency. The reason why this failure happens is that many PC users think this wireless network card‘s USB port or PCMCIA port supports hot plug, and it can plug and play. Actually, they take this plug-and-play function as random plug and few of them know that this wireless NIC card should not be plugged when working, for it is not only easy to hurt the card and its corresponding computer interface, but also likely to cause system crashes.
If your computer freezes up because of wireless network adapter plug, firstly, you need to confirm whether you have performed this action when the card is working, if so, you have to restart your computer.
In addition, in order to avoid this error, you’d better stop processes like information transmission and it’s best to disable your wireless network adapter in Device Manager before pulling out it.
Step 1 Click Start and select Control Panel.
Step 2 Double-click System to open the System Properties sheet.
Step 3 Click Hardware and choose Device Manager.
Step 4 Right-click the Network adapters and look at its properties.
Step 5 Disable and plug this card.
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Wireless Network Antenna – The Basics of Selecting an Antenna
Overview
The selection and deployment of access point antenna equipment affect network performance and availability. The signal strength or amount of energy radiated from an antenna has to do with antenna type and access point transmit specifications. It is expressed as effective isotropic radiated power (EIRP) and expressed as the sum of access point transmit power plus antenna gain minus cable loss. Cable length will increase signal attenuation or loss and should be minimized. Each antenna type will have a horizontal and vertical beam width specified. The antenna type, gain, cable length, number and mounting is all key to the design. For instance a directional antenna with high gain, no external cable, mounted at proper height will give best performance in an outside deployment with a lot of interference.
The wireless coverage cell on inside deployments can be extended with external antennas that plug into connectors on the access points. Most antennas can be mounted on the ceiling or wall and outside antennas often use a mast to increase height for line of sight.
Effective Isotropic Radiated Power = Transmit Power (dBm) + Gain (dB) – Cable Loss (dB)
Omni-Directional
Omni-directional antenna sends a horizontal radiated pattern of 360 degrees and a vertical pattern of 50 – 70 degrees from its source. From a practical perspective the pattern isn’t circular as much as being elliptical. It is a multi-homing antenna that sends signals to several clients in proximity causing some multipath fading that is minimized with antenna diversity. The gain values with 2.4 GHz antenna range from 2.2 dBi – 12 dBi. The higher gain antenna is deployed outside for the most part. Some Cisco access points have an integrated omni-directional dipole antenna or ” rubber ducky” that is standard with each device.
Directional
The directional antenna sends out a directed radiated pattern connecting with a distant antenna. The antenna purpose is to send traffic between antennas and not used for multi device homing. There are 3 specific directional antennas: Yagi, Patch and Dish. The Dish antenna has highest gain and narrowest radiation angle beam while Patch antenna has lowest gain and widest radiated beam. Gain values with 2.4 GHz antennas range from 6dBi – 21 dBi. Most antenna from this group are implemented in buildings with there is a lot of signal attenuation such as manufacturing, warehouses, and structures with a lot of steel, concrete, angled designs etc.
Diversity
The diversity antenna implement dual antenna on the access point receiving signals on both. The access point determines what antenna has best gain and transmits on that antenna. Diversity antennas are designed using either omni-directional, directional or dipole styles. Multipath fading occurs in buildings that have a lot of signal reflection. The signal finds multiple paths from source to destination and signal becomes distorted at receiver. This is minimized or eliminated with diversity antennas.
External Antenna
Some Cisco access points such as 1200 series have connectors available for an external antenna. This is available with deployments in environments where the access point is at a maximum 300 feet from the wired switch or signal distortion is excessive. The external antenna with a specified coax cable of 3 – 100 feet allow for placement of the antenna at optimal positioning. Minimizing the cable length will decrease signal attenuation before transmission. Implementing the higher gain diversity patch antenna fixes the problem of clients being out of range. The company could have deployed a repeater as an alternative solution with an 1100 series access point that doesn’t support an external antenna.
Building material and structural design will contribute to signal attenuation. The following describes from best to worst building material used with walls, floors and ceilings. Steel and concrete with several feet of construction is most difficult.
• Wood
• Concrete
• Reinforced Concrete
• Steel
Antenna Mounting
Access points should be ceiling mounted if possible at least 17 – 19 feet in height optimizing horizontal and vertical beam width. In some cases the access points will have to be mounted on the wall. Antenna mounting is important and should be implemented with instructions from the hardware installation guide. The Cisco access points utilize the standard RP-TNC 50 ohm type connector.
Outside Bridge Mounting
Companies have implemented a lot of Cisco wireless bridges that connect buildings in a campus network. The line of sight must be available or use a repeater bridge to extend the network where it isn’t available. Outside antennas deal with environmental issues and longer distances that require higher gain directional antennas. Mounting is usually with a mast or flat against a wall. Distances can extend around 250 – 500 feet or much further with higher wattage bridges, proper mounting of antenna and deploying repeaters.
Point to point topology is implemented a lot with outside wireless deployments. Point to multipoint topology is implemented both with inside and outside wireless deployments. The root bridge or root access point in a multipoint topology is homed with traffic from several non root bridges or access points. That topology is implemented with several spoke buildings and a hub or core office that must be networked outside. The spoke offices have a point to point connection with the hub office and the hub office has a multipoint connection with all spoke offices. The hub office will implement an omni-directional antenna with a lot of beam width while spoke offices will use a directional antenna.
The inside standard access point designs won’t have a group of directional antennas. Most will implement omni-directional antennas and use directional antennas where needed as a means of addressing distances. The outside implementations for the most part imply greater distances and environmental concerns making directional antennas an effective selection.
Cisco Wireless Network Design Guide available at amazon.com and eBookmall.com
Shaun Hummel is an author of various technical books and has a web site focused on information technology job search solutions and certifications.
http://www.networkjobsolutions.com
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How to Improve Your Wireless Network Signal? 3 Tactics You Cannot Afford Not to Know
Ever felt that your wireless network is not performing at its maximum capacity? Does your signal strength indicate that your connection is not as fast and reliable as it should be? There are some basic steps you can take to instantly improve your wireless experience…
You do not always need to go as far as replacing your antenna. Many people have found that by simply relocating the access point provides extremely satisfactory results. The location of your antenna is extremely important – you should move it to avoid obstacles and to give a clear “shot” to the rest of your network. You can even try raising the antenna. Additionally, there are a few basic steps you can take to ensure maximum network performance…
Use a Repeater
Using a wireless repeater is as simple as placing the device halfway between your access point and your computer. Make sure that you place the repeater a fair distance away from your access point. If they are too close together, a feedback loop can be created and damage the repeater.
Reduce Interference
Devices such as mobile phones, cordless phones or anything that transmits a radio frequency can possibly cause interference with your wireless network. Devices that use the 2.4GHz frequency range usually cause a problem. You should check if any of these devices are causing interference by disabling them and then assessing the performance of your network.
Upgrade Drivers and Firmware
Keeping up to date with the <a rel=”nofollow” onclick=”javascript:_gaq.push(['_trackPageview', '/outgoing/article_exit_link']);” href=”http://www.pcdriverhelper.com/Wireless+Devices.html”>latest drivers</a> and firmware is extremely important to maintain maximum performance. You should check for updates on your manufacturers website for your PCI, USB or PCMCIA wireless device. If you have a wireless router, manufacturers occasionally provide updates for the firmware of these devices. These updates are usually free and may increase performance.
You should aim for as much LOS (Line of Sight) between your antenna and computer as possible. Take note that the more walls and objects that are in between these devices will degrade the signal strength profusely.
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Wireless Home Networks – Setup Wireless Network
The way that it used to be, is people generally had one computer in their home. Internet access was based on dial-up modems which were connected directly with a serial cable on the home computer. No Local Area Network was needed. With the advancement of technology and the wide spread adoption of high speed internet connectivity at homes, necessitates that home appliances should be networked to facilitate online access and to also communicate and share information between them.
What I mean when I say home appliances is home computers, next generation game consoles, printers, scanners, network attached storage, etc. All of these “Appliances” need to share information amongst themselves over a network, but also need to have high-speed access to the Internet. To achieve that, you will need to set-up a home network. With a home based network you are technically building a local area network, which can be wired or wireless, that networked devices communicate between inside the home, and also share the same internet connection.
The base of the home network is your broadband router. This is usually a device that lets you setup a wired or a wireless network. You can use Ethernet cables if you’re making a wired network, or use Wi-Fi for wireless. This integrated router provides also the Internet access connectivity.
Once you have your home network setup, you can connect your computers, laptops, Xbox 360, Playstation 3, servers, network storage boxes, etc. After you successfully connect all your devices to the router, you can share and distribute your files over the network, have LAN parties on game consoles, play online video games, and share pictures between computer.
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How to Setup a Wireless Network with Linksys
The way that it used to be, is people generally had one computer in their home. World Wide Web access was based on dial-up modems which were connected directly with a serial cable on the home computer. No Local Area Network was needed. The fast progression of modern technology and the adoption of broadband Internet access connectivity at homes, necessitates that home appliances should be networked to facilitate online access and to also communicate and share information between them.
What I mean by home appliances is computers, gaming consoles, wired or wireless printers, and data storage devices like NAS. All of those devices need to communicated between themselves over a LAN, but also need to have high-speed access to the Internet. To achieve that, you will need to set-up a home network. With a home based network you are technically building a local area network, which can be wired or wireless, that networked devices communicate between inside the home, and also share a common broadband internet connectivity.
The heart of a home network is a broadband router. This is usually a device that lets you setup a wired or a wireless network. You can use Ethernet cables if you’re making a wired network, or use Wi-Fi for wireless. This integrated router provides also the Internet access connectivity.
Once you set up a home network, you can connect your home PC and laptop, XBOX or PlayStation consoles, Web cameras for security, Network Attached Storage (NAS) devices etc. After you connect those devices you can share files over the network, organize game parties, play online games, watch your home from the office using a Web Camera etc.
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Wireless Network Card Troubleshooting: Blue Screen of Death
As Wi-Fi hotspots are mushrooming all over the world, they let people have the chance to get rid of those inflexible network cables and surf on the net wirelessly in the WLAN. However, a high-performance wireless internet access is not an easy thing for some users, because when contacting with your wireless network, your wireless network adapter may probably meet a lot of strange failures, which may seriously affect your networking experience if you don’t fix them in time, and the blue screen is one that among those common failures.
If blue screen shows on your computer immediately after you installed a wireless network card, above all, you need to check whether the net card driver you installed is compatible with your operating system, for example, if your driver is only available in Windows 2000, but you have installed it in Windows XP, well then your computer would be more likely to have a blue screen. Therefore, make sure you have installed the correct network card driver.
If your driver is compatible with your system and has been installed properly, you need to go through the installation of this network adapter, and check whether it has inserted to the right slot or port properly, for if you pull out the card from its PCMCIA port on the motherboard or its USB port just a few seconds after plugging it, blue screen would lightly happen, because frequent pullout and plug may make network adapter’s corresponding port confused and fail to identify this adapter. Additionally, if you pull out your net card suddenly when its LINK light is blinking, that would also leads to blue screen, or even worse, your computer or your network card’s port would be damaged.
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Wireless Network Setup Notes
Having your own wireless connection at home can be very satisfying provided that it was setup properly and securely. There are things that you need to consider when doing your wireless network setup in order to have a strong and stable signal around the house all the time. You would not want your connection to be intermittent or unsecure. Learn how you can secure your wireless network to prevent hackers from grabbing your connection and possibly accessing your network.
Being wireless is freedom, no strings attached. It means that you can roam around not minding any cable connections, especially if you are using a laptop or mobile device like a smart phone to connect to the internet. The wireless device that broadcasts the signal could be a wireless modem router or a standalone modem or router. This device should be located in an open space not close to any other device that sends wireless signal as well, like a baby monitor, cordless phone or microwave that will affect the signal quality and cause an intermittent connection.
During your wireless network setup, securing your wireless connection is critical. You don’t want your neighbors to have free internet connection at your expense, right? Setting up a WEP or WPA key is one of the basic ways to secure your connection. These settings can be found at the user interface (UI) of your router. In order to access this page you need to know what the IP address of your device is, you can check it at the bottom of the device or in the manual.
Data transfer is slower when compared to a wired connection so it is not advisable to transfer or download files while using wireless. This is one of the disadvantages of having a wireless connection. If your house is not getting a decent signal throughout the entire house, you can use a wireless repeater. This device repeats the signal from the router to make the coverage larger. A wireless repeater is a small device with an antenna that collects the signal then passes it around. This will ensure that no matter where you are, you will have a strong signal.
How to Set Up a Wireless Network Using Satellite Internet Service
If you live out in the country and can’t get high speed Internet access, satellite Internet acess will provide you the best option to surf the net at broadband speeds. In addition to being able to get broadband speeds, you are not just restricted to one coax cable connecting one computer. You have the ability to use a wireless connection. You can network your home or office computers easier, and you can several people surf the Internet on different computers at the same time.
The first step to establishing your wireless network is to choose a reliable satellite Internet service provider. Two-way satellite Internet service offers you the most efficient service. The three best companies satellite internet access companies are Starband, Hughesnet and my favorite Wildblue. There are a couple of one-way service providers but I would stay away from them. Unless you want to tie up you phone line and want other headaches!
After you have selected a satellite Internet service provider you will want to go out a purchase the necessary equipment to go wireless. If you don’t have a computer that has an internal wireless networking card already built in then, you will want to either buy one that does, or you will want to buy a wireless network adapter. After you have established the network card you will need a wireless router. I would stick with the known brands such as linksys, Netgear or D-link. These three manufacturers are dependable and easy to set up.
After your satellite Internet service has been installed you will be ready to connect your wireless network. Start by connecting your satellite Internet modem to the router. Your router will then send signals to your computer via infrared signals. Configure your router following the instructions that came with your router.
If you are using a wireless network adapter you will want to plug this into a USB port in your computer. If your computer came with an internal wireless card you should receive the signal through the card. If you purchased your router before installation, most installers will assist you in setting up your router. If not, just follow the instructions per the router manual. It’s pretty simple!
There is one thing to keep in mind. When two or more people are surfing the Internet at one time, the Internet connection speed is shared. So if you subscribe to a service using 512k speeds, you both could be splitting the speed. With this in mind be selective when choosing your satellite Internet Service plans. You will all then be happier with your satellite Internet service in the end.
Setting up a wireless system with your satellite Internet service will provide you with the speed that you have been lacking with the flexibility to share the connection with family or co-workers. It offers a great combination!
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Make Sure to Have a Safe Wireless Network
Do you use a wireless network at home to connect to the internet? Do you know whether or not others are connecting to your wireless network without your knowledge? You must protect your wireless network from unauthorized users logging on to the internet through your wireless router. There are multiple ways in which to do this and by following a few simple rules, you can also be comfortable in the fact that your internet connection is safe.
First, always set a password on your device. A good password needs to be at least eight characters in length, using a combination of letters, numbers, and special characters. Doing this will prevent unauthorized access to the router.
Use a DNS filter. There will be a section where you can exclude all computers except those with certain DNS values. The DNS value is a string of characters generated by the computer’s network adapter. This string is unique to every computer. So by entering just your family’s DNS strings, you’ll be allowing those computers access, but preventing access from everyone else. To find a computer’s DNS string, click on Start, then type CMD and press Enter. (For XP click Start, then Run, and then type CMD and press Enter.) In the black command window, type “ipconfig -all” (without the quotes) and press Enter. In the section that describes your wireless adapter, you’ll see a line showing the physical address. That’s the DNS string.
Turn off your wireless router if you are not using it. Disabling the router’s DHCP service, can also help achieve you a secure wireless network. A DHCP server allots network settings each wireless computer in the network so that they can access Wi-Fi connection. If you configure wireless internet connection settings manually by providing all the computer in the network a distinct IP address and subnet mask, you will make the network secure as the router will give access to these computers to access the internet connection.
Use a Secure Connection: If you use the Internet for financial purposes like online banking or stock trading at places like an Internet cafe, verify the website is using a secure connection. When a secure connection is active, a padlock icon is visible at the bottom of your web browser. Another way to confirm that the website uses a secure connection is when its URL begins with https and not http.
