What Is VSAT?
- Details
- Category: Network Technology
- Published on Saturday, 02 April 2011 11:00
- Written by Administrator
- Hits: 4336
A Very Small Aperture Terminal (VSAT), is a two-way satellite ground station or a stabilized maritime Vsat antenna with a dish antenna that is smaller than 3 meters. The majority of VSAT antennas range from 75 cm to 1.2 m. Data rates typically range from 56 Kbit/s up to 4 Mbit/s. VSATs access satellites in geosynchronous orbit to relay data from small remote earth stations (terminals) to other terminals (in mesh configurations) or master earth station "hubs" (in star configurations).
VSATs are most commonly used to transmit narrowband data (point of sale transactions such as credit card, polling or RFID data; or SCADA), or broadband data (for the provision of Satellite Internet access to remote locations, VoIP or video). VSATs are also used for transportable, on-the-move (utilising phased array antennas) or mobile maritime communications.
The concept of the geostationary orbit was originated by Russian theorist Konstantin Tsiolkovsky, who wrote articles on space travel at the turn of the century. In the 1920s, Hermann Oberth and Herman Potocnik, aka Herman Noordung described an orbit at an altitude of 35,900 kilometers whose period exactly matched the Earth's rotational period, making it appear to hover over a fixed point on the Earth's equator.
Arthur C. Clarke contributed to the understanding of satellites through an article published in Wireless World in October 1945 titled "Extra-Terrestrial Relays: Can Rocket Stations Give World-wide Radio Coverage?". In this article, Clarke not only determines the orbital characteristics necessary for a geostationary orbit, but also discusses the frequencies and power needed for communications.
Most VSAT networks are configured in one of these topologies:
A star topology, using a central uplink site, such as a network operations center (NOC), to transport data back and forth to each VSAT terminal via satellite,
A mesh topology, where each VSAT terminal relays data via satellite to another terminal by acting as a hub, minimizing the need for a centralized uplink site,
A combination of both star and mesh topologies. Some VSAT networks are configured by having several centralized uplink sites (and VSAT terminals stemming from it) connected in a multi-star topology with each star (and each terminal in each star) connected to each other in a mesh topology. Others configured in only a single star topology sometimes will have each terminal connected to each other as well, resulting in each terminal acting as a central hub. These configurations are utilized to minimize the overall cost of the network, and to alleviate the amount of data that has to be relayed through a central uplink site (or sites) of a star or multi-star network.
Constituent parts of a VSAT configuration
Antenna
Block upconverter (BUC)
Low-noise block converter (LNB)
Orthomode transducer (OMT)
Interfacility Link Cable (IFL)
Indoor unit (IDU)
All the outdoor parts on the dish are collectively called the ODU (Outdoor Unit), i.e. OMT to split signal between BUC and LNB. The IDU is effectively a Modem, usually with ethernet port and 2 x F-connectors for the coax to BUC(Transmit) and from LNB (Receive). The Astra2Connect has an all-in-one OMT/BUC/LNA that looks like a QUAD LNB in shape and size which mounts on a regular TV sat mount. As a consequence it is only 500 mW compared with the normal 2W, thus is poorer in rain.
What Is VSAT?
- Details
- Category: Network Technology
- Published on Saturday, 02 April 2011 11:00
- Written by Administrator
- Hits: 4336
A Very Small Aperture Terminal (VSAT), is a two-way satellite ground station or a stabilized maritime Vsat antenna with a dish antenna that is smaller than 3 meters. The majority of VSAT antennas range from 75 cm to 1.2 m. Data rates typically range from 56 Kbit/s up to 4 Mbit/s. VSATs access satellites in geosynchronous orbit to relay data from small remote earth stations (terminals) to other terminals (in mesh configurations) or master earth station "hubs" (in star configurations).
VSATs are most commonly used to transmit narrowband data (point of sale transactions such as credit card, polling or RFID data; or SCADA), or broadband data (for the provision of Satellite Internet access to remote locations, VoIP or video). VSATs are also used for transportable, on-the-move (utilising phased array antennas) or mobile maritime communications.
The concept of the geostationary orbit was originated by Russian theorist Konstantin Tsiolkovsky, who wrote articles on space travel at the turn of the century. In the 1920s, Hermann Oberth and Herman Potocnik, aka Herman Noordung described an orbit at an altitude of 35,900 kilometers whose period exactly matched the Earth's rotational period, making it appear to hover over a fixed point on the Earth's equator.
Arthur C. Clarke contributed to the understanding of satellites through an article published in Wireless World in October 1945 titled "Extra-Terrestrial Relays: Can Rocket Stations Give World-wide Radio Coverage?". In this article, Clarke not only determines the orbital characteristics necessary for a geostationary orbit, but also discusses the frequencies and power needed for communications.
Most VSAT networks are configured in one of these topologies:
A star topology, using a central uplink site, such as a network operations center (NOC), to transport data back and forth to each VSAT terminal via satellite,
A mesh topology, where each VSAT terminal relays data via satellite to another terminal by acting as a hub, minimizing the need for a centralized uplink site,
A combination of both star and mesh topologies. Some VSAT networks are configured by having several centralized uplink sites (and VSAT terminals stemming from it) connected in a multi-star topology with each star (and each terminal in each star) connected to each other in a mesh topology. Others configured in only a single star topology sometimes will have each terminal connected to each other as well, resulting in each terminal acting as a central hub. These configurations are utilized to minimize the overall cost of the network, and to alleviate the amount of data that has to be relayed through a central uplink site (or sites) of a star or multi-star network.
Constituent parts of a VSAT configuration
Antenna
Block upconverter (BUC)
Low-noise block converter (LNB)
Orthomode transducer (OMT)
Interfacility Link Cable (IFL)
Indoor unit (IDU)
All the outdoor parts on the dish are collectively called the ODU (Outdoor Unit), i.e. OMT to split signal between BUC and LNB. The IDU is effectively a Modem, usually with ethernet port and 2 x F-connectors for the coax to BUC(Transmit) and from LNB (Receive). The Astra2Connect has an all-in-one OMT/BUC/LNA that looks like a QUAD LNB in shape and size which mounts on a regular TV sat mount. As a consequence it is only 500 mW compared with the normal 2W, thus is poorer in rain.
www
- Details
- Category: Network Technology
- Published on Sunday, 28 February 2010 17:16
- Written by Administrator
- Hits: 4337
The World Wide Web, abbreviated as WWW and commonly known as The Web, is a system of interlinked hypertext documents contained on the Internet. With a web browser, one can view web pages that may contain text, images, videos, and other multimedia and navigate between them by using hyperlinks. Using concepts from earlier hypertext systems, British engineer and computer scientist Sir Tim Berners Lee, now the Director of the World Wide Web Consortium, wrote a proposal in March 1989 for what would eventually become the World Wide Web. He was later joined by Belgian computer scientist Robert Cailliau while both were working at CERN in Geneva, Switzerland. In 1990, they proposed using "HyperText [...] to link and access information of various kinds as a web of nodes in which the user can browse at will", and released that web in December.
In March 1989, Tim Berners-Lee wrote a proposal that referenced ENQUIRE, a database and software project he had built in 1980, and described a more elaborate information management system.With help from Robert Cailliau, he published a more formal proposal (on November 12, 1990) to build a "Hypertext project" called "WorldWideWeb" (one word, also "W3") as a "web" of "hypertext documents" to be viewed by "browsers", using a client-server architecture.This proposal estimated that a read-only web would be developed within three months and that it would take six months to achieve, "the creation of new links and new material by readers, [so that] authorship becomes universal" as well as "the automatic notification of a reader when new material of interest to him/her has become available". See Web 2.0 and RSS/Atom, which have taken a little longer to mature.
www
- Details
- Category: Network Technology
- Published on Sunday, 28 February 2010 17:16
- Written by Administrator
- Hits: 4337
The World Wide Web, abbreviated as WWW and commonly known as The Web, is a system of interlinked hypertext documents contained on the Internet. With a web browser, one can view web pages that may contain text, images, videos, and other multimedia and navigate between them by using hyperlinks. Using concepts from earlier hypertext systems, British engineer and computer scientist Sir Tim Berners Lee, now the Director of the World Wide Web Consortium, wrote a proposal in March 1989 for what would eventually become the World Wide Web. He was later joined by Belgian computer scientist Robert Cailliau while both were working at CERN in Geneva, Switzerland. In 1990, they proposed using "HyperText [...] to link and access information of various kinds as a web of nodes in which the user can browse at will", and released that web in December.
In March 1989, Tim Berners-Lee wrote a proposal that referenced ENQUIRE, a database and software project he had built in 1980, and described a more elaborate information management system.With help from Robert Cailliau, he published a more formal proposal (on November 12, 1990) to build a "Hypertext project" called "WorldWideWeb" (one word, also "W3") as a "web" of "hypertext documents" to be viewed by "browsers", using a client-server architecture.This proposal estimated that a read-only web would be developed within three months and that it would take six months to achieve, "the creation of new links and new material by readers, [so that] authorship becomes universal" as well as "the automatic notification of a reader when new material of interest to him/her has become available". See Web 2.0 and RSS/Atom, which have taken a little longer to mature.
Install Windows XP Professional by using Remote Installation Services (RIS).
- Details
- Category: Network Technology
- Published on Wednesday, 17 June 2009 16:16
- Written by Administrator
- Hits: 5097
Many desktop support professionals and even network administrators do not have experience with RIS because it is infrequently used by larger organizations that rely on more full-featured tools such as Ghost, SMS, or Altiris. I am fortunate to have consulted with a state agency to deploy RIS into the environment, create desktop images, and develop a roll-out plan using RIS throughout the organization. I hope some this experience will help you when it comes time to answer RIS questions on the 70-270 Windows XP Professional certification exam.
To deploy RIS, your network infrastructure must be able to support RIS-based installations. Also, DNS and Dynamic Host Configuration Protocol (DHCP) servers must be running on the network and you must have the Active Directory service installed. The server you are using must have a separate partition from the system drive, formatted in NTFS, and have at least 2GB free. The system partition cannot be used for deploying RIS images.
RIS uses Pre-boot eXecution Environment (PXE) technology to enable client computers without an operating system to boot remotely to a RIS server that performs installation of a supported operating system over a TCP/IP network connection. You can deploy one or more RIS servers to accommodate your client operating system needs, but each client must have compatible hardware, which includes a BIOS and network adapter that support the remote-boot process. You can create different sets of RIS images to accommodate various configurations of different groups of client computers. You can also use Group Policy settings to limit the installation options that RIS presents to clients. You can use RIS to provide interactive operating system installations that require user input, or fully-automated installations that require no user input other than logon credentials.
Please note: you can only use RIS to perform a clean installation of the Operating System, you cannot use it to perform an Operating System upgrade.
Installing RIS on a Windows 2003 Server
1. Open Control Panel > Add/Remove Programs.
2. Click on Add/Remove Windows Components.
3. Scroll down and select Remote Installation Services. Click Next.
4. Click Finish to compete the installation of RIS.
5. Click Yes to restart the server.
6. Login to the server.
7. Open Administrative Tools > Remote Installation Services Setup.
8. Click Next.
9. Select the location for your installation folder. Please note: this installation folder cannot be on the system drive, it must be on a separate partition. Click Next.
10. Check the Respond to client computers requesting service. Click Next.
11. Enter the path to the CD drive containing the Windows XP installation CD. Click Next.
12. Enter the folder name for the Windows installation files. Click Next.
13. If you like the defaults, click Next.
14. Click Finish.
15. RIS copies the files needed and configures itself to deploy to clients.
16. Once the setup process is complete, click Done.
17. If you need to add another OS image to the server, open the Remote Installation Services Setup wizard again.
18. Click Next at the welcome screen and on this screen click Next.
19. Now follow the same process as we followed below and add a second image.
Using RIS
1. Boot the computer you would like to use RIS to image.
2. When the PXE Boot Agent loads, press whatever key is necessary for a network service boot.
3. Press Enter to continue.
4. Enter a valid user name and password to connect to the RIS server. Press Enter to continue.
5. Press Enter to continue.
6. Press Enter to continue.
7. Setup copies files and begins Windows installation.
8. Windows follows the standard installation process since we did not specify an answer file for this particular image.
Automating the Windows XP Installation Using RIS
1. Copy the contents of the Deploy.cab file from the Windows XP Professional installation CD to the hard drive of your server.
2. Expand the files from the CAB.
3. Run Setup Manager.
4. Click Next at the Welcome Screen.
5. Select Create a New Answer File and click Next.
6. Select Remote Installation Services and click Next.
7. You have the same options as we described earlier in Setup Manager. We selected Fully automated for this particular installation. Click Next.
8. Accept the terms of the license agreement and click Next.
9. Complete the Windows setup parameters.
10. When you fill out all of the options, select a location to save the file.
11. Close Setup Manager.
Associating an Answer File to an Image
1. Open up the Active Directory Users and Computers snap-in.
2. Open Domain Controllers (or wherever your RIS server resides in AD). Select the RIS server, right-click, and select Properties.
3. Click on the Remote Install tab.
4. Click on Advanced Settings.
5. Click on the Images tab.
6. Click Add.
7. Click Next.
8. Click An Alternate Location and click Next.
9. Select the image you want to associate to and click Next.
10. Click Browse and navigate to where you have your answer file. Click Next.
11. Change any friendly description information and click Next.
12. Click Finish.
13. You now have your original image and the new image you just created with the answer file you just associated with it.
Creating an Image Using Riprep
The final method to create an image is to use Riprep. Riprep allows you to create a more full featured image – one with software applications installed, settings configured, etc. You run Riprep from the target machine you want imaged, so it contains everything as you have configured it.
1. Configure the target machine you want to image with all of the applications and settings you require.
2. On the machine that you want to image, run this command:
\\servername\reminst\admin\i386\riprep.exe /pnp
This command runs riprep and adds plug’n’play enumeration during installation to identify and load device drivers for changed hardware on the “to be imaged” PC.
3. Click Next.
4. Your server name will be different. If you want to create this image on a different RIS server, you could by changing the server name here. Click Next.
5. Type in the name of the folder you want to use on the RIS server.
6. Enter in a description and help text, click Next.
7. Riprep will stop services to continue. Click Next.
8. Review the settings and click Next.
9. Click Next to begin the imaging process.
10. The beautifully designed RIP Wizard runs and copies your image.
11. When it is complete, you can shut down the computer.
12. If you go to the RIS Server, look at the server properties, Remote Install, Advanced, and then the Images tab. You will see the new image we just created, Windows XP Global Installation v1 is now present on the server. You can begin deploying the image using the methods we described earlier.
