Before we talk about wireless network security, we must first understand how a wireless network operates.
For most home and small business users, a wireless network is basically a set of devices that enable all of the personal computers in your location to use a broadband internet connection simultaneously.
Wireless networks don't use cables for connections, but instead use radio waves, like cordless phones. Also known as Wi-Fi, or Wireless Fidelity, wireless networks allow you to use your networked computers or laptops anywhere in an office or home.
Wireless networking is also available in public "hotspots," like coffee shops, hotel rooms and lobbies, and airports.
You may have heard the term "Internet Cafe". This refers to a place of business (most often, a coffee shop) which offers wireless network access for anyone who wants to bring in a laptop equipped with a wireless network card. The wireless network card picks up the wireless network signal and the two communicate over that signal. Here's a web page which talks about the wireless network security risks of using Internet Cafes, if you are interested.
But, just as with a cell phone, a wireless network (and any computer you have connected to it) can be hacked, especially if it isn't secured.
CAVEAT and Disclaimer: Wireless networks are inherently unsafe and cannot be completely secured, as there are hackers who will always be one step ahead of the commercial security vendors.
So I, Ellen Davis, do not guarantee that your wireless network security will be impenetrable after completing the steps offered on this site.
However, in my opinion, the majority of hackers are going after bigger fish, and don't have much interest in your wireless home network, except maybe to use it for free internet access.
So unless you are storing hundreds of credit card numbers on your computers for some reason, or you have some kind of important information that can be sold on the black market, or you make some hacker mad, applying the steps below will help ensure your wireless network security is at least better than it would be if you did nothing.
Let's take a closer look at setting up a wireless network and the best practices for building in wireless network security.
First, here’s a list of components needed to build a basic home or small office wireless network:
1. Windows based personal computers, and/or personal laptops with Windows XP SP2 installed. (Windows XP SP2 is compatible with WPA2 Personal encryption, which is what I recommend using).
2. WPA2 enabled wired or wireless network adapters, which should be (or may already be) installed in each of your computers.
If you aren't sure whether Windows XP and the network cards installed on your computer are enabled for WPA2, here's an excellent page that walks you through how to upgrade Windows XP, routers and network cards to WPA2.
3. Ethernet cables, also known as CAT5 cables. They come in 3, 6, 10, 25, and 50 foot lengths. Desktop and laptop computers won’t need a cable if a wireless network card in installed.
4. A wireless router that supports WPA and WPA2 encryption. There are many different brands, but I use Linksys wireless routers because they are reliable and easy to set up. They cost around $60 in the big office supply or computer stores.
5. A broadband internet connection.
6. The wireless network security steps below.
Second, you need steps on how to secure a wireless network. I've included the details on how to implement reliable wireless network security below: (I'm assuming that we are in your home or small business office, and that you have a desktop PC wired into your broadband box and that you will be using a new Linksys router):
1. First, you must have either a regular or wireless network card in all of the computers in your house. For most wireless networks, a desktop computer nearest to the broadband jack will be connected via a wired network card and cable. Laptops or any other computer not close to the router will be connected via wireless card (or long CAT 5 cable).
IMPORTANT Note: If you have older network cards, they may not be compatible with the new WPA2 security protocol. Upgrade the drivers or the cards if you have to, because relying on any other security protocol like WEP is just not as good when it comes to wireless security.
You may also need to upgrade Windows XP SP2 to be compatible with WPA2 security. Here's the Microsoft page to do this.
2. If you haven’t done so already, place an order for a broadband (aka high speed) internet service installation with your local internet service provider. (This can be a cable company, the telephone company or a wireless tower provider – shop around for the best deal).
3. Purchase a wireless router and install it. NOTE: Be careful about buying used routers; the previous owner could install malicious software on them that could hurt your computer. New is better if you don’t know how to clean them up.
4. Following the instructions that come with the router, set it up next to the computer that is plugged into the broadband connection box.
5. IMPORTANT!! SECURE your wireless router. Follow each of these steps to make sure your wireless network security is reliable and your network is safe from outside intrusion:
* Change the default wireless network name or SSID to something unique but not personal (no social security numbers or house addresses). The name you choose can be up to 32 characters long and you need to be able to remember it. Linksys sets the default name to Linksys on their routers and every hacker in the world knows that, so don’t leave it unchanged.
* Change the default password. Linksys sets a default password of admin, and every hacker knows that too. Change it to a password that includes both letters and numbers. Avoid using words that can be found in a dictionary. Also, make sure you either remember it or note it somewhere secure. You will need if you want to access your router later to make changes.
* Enable Encryption. Linksys routers offer several kinds of security protocols – WPA, WPA2 and WEP are the major types.
The newest and most secure kind of encryption is WPA2. Both WEP and WPA have already been cracked by hackers. WPA2 is the most secure, so I would implement it over the other choices.
When the router setup asks you to choose a wireless security encryption method, choose security mode "WPA2 Personal". Then choose algorithms "TKIP+AES". Choose a strong password for your encryption key, such as a combination of letters and numbers. It can be from 8 to 63 characters, I would use at least 14 characters. Leave the key renewal interval as it is, and save the setting. Make sure you can remember the key. I hate to tell you to write it down, but if you must, you must.
Later, when you try to connect your wireless clients to your network, the card utility should automatically ask you for the preshared key. Enter it twice and you should get connected. If not, please check that the wireless card in the computer is actually compatible with WPA/WPA2.
Note: If you have an older router that supports WEP only, and you don't want to upgrade it, please remember that WEP is very easy to crack, so your wireless network won't be as secure. You'll be at least safer if you use 128-bit WEP keys, but I would recommend that you check the router manufacturer's website for a firmware upgrade that will add WPA support.
* DON'T turn off SSID Broadcasting. A wireless router can broadcast its SSID name by sending out a continuous radio ping. This is convenient for people trying to connect to it, because they don’t have to remember the name of the network. It seems like it would be good to turn that off, but on Windows XP, it isn't a good idea.
Windows XP, by default, always tries to connect to the first broadcasted wireless network. If you turn off SSID broadcasting, Windows XP won't connect to your network first if it finds a broadcasting network in close enough range. That's not good wireless network security, for sure. So it's best to continue broadcasting while implementing WPA2 encryption instead.
Plus you won't have to choose to connect to "nonbroadcasting networks" on your computers, and then type in the name of the network to connect to it.
* You have now successfully implemented wireless network security on your router that should keep your data relatively safe (see caveat above for more info).
Let's keep going to finish setting up our network, and connecting to the internet.
6. Change the network card settings in each of your PCs to match the router settings. Pay particular attention to the SSID, the type of encryption, and the key you used when you set up the router.
You’ll need to know this info when are ready to connect any wireless PCs or laptops. Wired computers will get the information they need automatically, as long as the network card is set up to use DHCP, which basically means the network card goes out and gets what it needs from the network automatically.
7. If you have a laptop with a wireless card, check to make sure the wifi capabilities are on. NOTE: On some laptops, there is a switch or button on the laptop that turns the wireless network card on or off. If you are having trouble "seeing" the wireless network, you may have to "turn on" your wireless network card.
8. Once your computer network cards have the network information that matches the router, they will connect and you’ll be able to connect to the internet, with confidence that your wireless network security is set up correctly.
9. Note: Look for the wireless signal strength in the system tray located in the bottom right hand corner of your Windows desktop. It will look a bunch of colored bars.
Green means the signal is strong, yellow is weaker, and red means no signal at all.
Walk around your house with your laptop and see how good the signal is in each room.
Being able to work anywhere in your house depends on how big your house is, and where your wireless router is located. As you walk around, you’ll see the signal strength icon in the Windows system tray changed.
Very quickly, you’ll find out the best places to be for full network speed. It's makes working on your computer kind of fun, and now you have the peace of mind that your wireless network security is keeping your computers safe.
All done! You now know the best steps for setting up a wireless network and configuring strong wireless network security. I hope this information helps you keep your computers and your data safe.
One more note: If setting up wireless network security seems a little overwhelming, and you live in Cheyenne, Wyoming, I can help. Send me a note via my contact form, and I’d be happy to come out and set it up for you. My rates are reasonable.
http://www.sensible-computer-help.com
Nework Hardware
What is Networking Hardware?
Networking hardware includes all computers, peripherals, interface cards and other equipment needed to perform data-processing and communications within the network. CLICK on the terms below to learn more about those pieces of networking hardware.
This section provides information on the following components:
* File Servers
* Workstations
* Network Interface Cards
* Switches
* Repeaters
* Bridges
* Routers
File Servers
A file server stands at the heart of most networks. It is a very fast computer with a large amount of RAM and storage space, along with a fast network interface card. The network operating system software resides on this computer, along with any software applications and data files that need to be shared.
The file server controls the communication of information between the nodes on a network. For example, it may be asked to send a word processor program to one workstation, receive a database file from another workstation, and store an e-mail message during the same time period. This requires a computer that can store a lot of information and share it very quickly. File servers should have at least the following characteristics:
* 800 megahertz or faster microprocessor (Pentium 3 or 4, G4 or G5)
* A fast hard drive with at least 120 gigabytes of storage
* A RAID (Redundant Array of Inexpensive Disks) to preserve data after a disk casualty
* A tape back-up unit (i.e. DAT, JAZ, Zip, or CD-RW drive)
* Numerous expansion slots
* Fast network interface card
* At least of 512 MB of RAM
Workstations
All of the user computers connected to a network are called workstations. A typical workstation is a computer that is configured with a network interface card, networking software, and the appropriate cables. Workstations do not necessarily need floppy disk drives because files can be saved on the file server. Almost any computer can serve as a network workstation.
Network Interface Cards
The network interface card (NIC) provides the physical connection between the network and the computer workstation. Most NICs are internal, with the card fitting into an expansion slot inside the computer. Some computers, such as Mac Classics, use external boxes which are attached to a serial port or a SCSI port. Laptop computers can now be purchased with a network interface card built-in or with network cards that slip into a PCMCIA slot.
Network interface cards are a major factor in determining the speed and performance of a network. It is a good idea to use the fastest network card available for the type of workstation you are using.
The three most common network interface connections are Ethernet cards, LocalTalk connectors, and Token Ring cards. According to a International Data Corporation study, Ethernet is the most popular, followed by Token Ring and LocalTalk (Sant'Angelo, R. (1995). NetWare Unleashed, Indianapolis, IN: Sams Publishing).
Ethernet Cards
Ethernet cards are usually purchased separately from a computer, although many computers (such as the Macintosh) now include an option for a pre-installed Ethernet card. Ethernet cards contain connections for either coaxial or twisted pair cables (or both) (See fig. 1). If it is designed for coaxial cable, the connection will be BNC. If it is designed for twisted pair, it will have a RJ-45 connection. Some Ethernet cards also contain an AUI connector. This can be used to attach coaxial, twisted pair, or fiber optics cable to an Ethernet card. When this method is used there is always an external transceiver attached to the workstation. (See the Cabling section for more information on connectors.)
Fig. 1. Ethernet card.
From top to bottom:
RJ-45, AUI, and BNC connectors
LocalTalk Connectors
LocalTalk is Apple's built-in solution for networking Macintosh computers. It utilizes a special adapter box and a cable that plugs into the printer port of a Macintosh (See fig. 2). A major disadvantage of LocalTalk is that it is slow in comparison to Ethernet. Most Ethernet connections operate at 10 Mbps (Megabits per second). In contrast, LocalTalk operates at only 230 Kbps (or .23 Mbps).
Fig.2. LocalTalk connectors
Ethernet Cards vs. LocalTalk Connections
Ethernet LocalTalk
Fast data transfer (10 to 100 Mbps) Slow data transfer (.23 Mbps)
Expensive - purchased separately Built into Macintosh computers
Requires computer slot No computer slot necessary
Available for most computers Works only on Macintosh computers
Token Ring Cards
Token Ring network cards look similar to Ethernet cards. One visible difference is the type of connector on the back end of the card. Token Ring cards generally have a nine pin DIN type connector to attach the card to the network cable.
Switch
A concentrator is a device that provides a central connection point for cables from workstations, servers, and peripherals. In a star topology, twisted-pair wire is run from each workstation to a central switch/hub. Most switches are active, that is they electrically amplify the signal as it moves from one device to another. Switches no longer broadcast network packets as hubs did in the past, they memorize addressing of computers and send the information to the correct location directly. Switches are:
* Usually configured with 8, 12, or 24 RJ-45 ports
* Often used in a star or star-wired ring topology
* Sold with specialized software for port management
* Also called hubs
* Usually installed in a standardized metal rack that also may store netmodems, bridges, or routers
Repeaters
Since a signal loses strength as it passes along a cable, it is often necessary to boost the signal with a device called a repeater. The repeater electrically amplifies the signal it receives and rebroadcasts it. Repeaters can be separate devices or they can be incorporated into a concentrator. They are used when the total length of your network cable exceeds the standards set for the type of cable being used.
A good example of the use of repeaters would be in a local area network using a star topology with unshielded twisted-pair cabling. The length limit for unshielded twisted-pair cable is 100 meters. The most common configuration is for each workstation to be connected by twisted-pair cable to a multi-port active concentrator. The concentrator amplifies all the signals that pass through it allowing for the total length of cable on the network to exceed the 100 meter limit.
Bridges
A bridge is a device that allows you to segment a large network into two smaller, more efficient networks. If you are adding to an older wiring scheme and want the new network to be up-to-date, a bridge can connect the two.
A bridge monitors the information traffic on both sides of the network so that it can pass packets of information to the correct location. Most bridges can "listen" to the network and automatically figure out the address of each computer on both sides of the bridge. The bridge can inspect each message and, if necessary, broadcast it on the other side of the network.
The bridge manages the traffic to maintain optimum performance on both sides of the network. You might say that the bridge is like a traffic cop at a busy intersection during rush hour. It keeps information flowing on both sides of the network, but it does not allow unnecessary traffic through. Bridges can be used to connect different types of cabling, or physical topologies. They must, however, be used between networks with the same protocol.
Routers
A router translates information from one network to another; it is similar to a superintelligent bridge. Routers select the best path to route a message, based on the destination address and origin. The router can direct traffic to prevent head-on collisions, and is smart enough to know when to direct traffic along back roads and shortcuts.
While bridges know the addresses of all computers on each side of the network, routers know the addresses of computers, bridges, and other routers on the network. Routers can even "listen" to the entire network to determine which sections are busiest -- they can then redirect data around those sections until they clear up.
If you have a school LAN that you want to connect to the Internet, you will need to purchase a router. In this case, the router serves as the translator between the information on your LAN and the Internet. It also determines the best route to send the data over the Internet. Routers can:
* Direct signal traffic efficiently
* Route messages between any two protocols
* Route messages between linear bus, star, and star-wired ring topologies
* Route messages across fiber optic, coaxial, and twisted-pair cabling
Type rest of the post here
Networking hardware includes all computers, peripherals, interface cards and other equipment needed to perform data-processing and communications within the network. CLICK on the terms below to learn more about those pieces of networking hardware.
This section provides information on the following components:
* File Servers
* Workstations
* Network Interface Cards
* Switches
* Repeaters
* Bridges
* Routers
File Servers
A file server stands at the heart of most networks. It is a very fast computer with a large amount of RAM and storage space, along with a fast network interface card. The network operating system software resides on this computer, along with any software applications and data files that need to be shared.
The file server controls the communication of information between the nodes on a network. For example, it may be asked to send a word processor program to one workstation, receive a database file from another workstation, and store an e-mail message during the same time period. This requires a computer that can store a lot of information and share it very quickly. File servers should have at least the following characteristics:
* 800 megahertz or faster microprocessor (Pentium 3 or 4, G4 or G5)
* A fast hard drive with at least 120 gigabytes of storage
* A RAID (Redundant Array of Inexpensive Disks) to preserve data after a disk casualty
* A tape back-up unit (i.e. DAT, JAZ, Zip, or CD-RW drive)
* Numerous expansion slots
* Fast network interface card
* At least of 512 MB of RAM
Workstations
All of the user computers connected to a network are called workstations. A typical workstation is a computer that is configured with a network interface card, networking software, and the appropriate cables. Workstations do not necessarily need floppy disk drives because files can be saved on the file server. Almost any computer can serve as a network workstation.
Network Interface Cards
The network interface card (NIC) provides the physical connection between the network and the computer workstation. Most NICs are internal, with the card fitting into an expansion slot inside the computer. Some computers, such as Mac Classics, use external boxes which are attached to a serial port or a SCSI port. Laptop computers can now be purchased with a network interface card built-in or with network cards that slip into a PCMCIA slot.
Network interface cards are a major factor in determining the speed and performance of a network. It is a good idea to use the fastest network card available for the type of workstation you are using.
The three most common network interface connections are Ethernet cards, LocalTalk connectors, and Token Ring cards. According to a International Data Corporation study, Ethernet is the most popular, followed by Token Ring and LocalTalk (Sant'Angelo, R. (1995). NetWare Unleashed, Indianapolis, IN: Sams Publishing).
Ethernet Cards
Ethernet cards are usually purchased separately from a computer, although many computers (such as the Macintosh) now include an option for a pre-installed Ethernet card. Ethernet cards contain connections for either coaxial or twisted pair cables (or both) (See fig. 1). If it is designed for coaxial cable, the connection will be BNC. If it is designed for twisted pair, it will have a RJ-45 connection. Some Ethernet cards also contain an AUI connector. This can be used to attach coaxial, twisted pair, or fiber optics cable to an Ethernet card. When this method is used there is always an external transceiver attached to the workstation. (See the Cabling section for more information on connectors.)
Fig. 1. Ethernet card.
From top to bottom:
RJ-45, AUI, and BNC connectors
LocalTalk Connectors
LocalTalk is Apple's built-in solution for networking Macintosh computers. It utilizes a special adapter box and a cable that plugs into the printer port of a Macintosh (See fig. 2). A major disadvantage of LocalTalk is that it is slow in comparison to Ethernet. Most Ethernet connections operate at 10 Mbps (Megabits per second). In contrast, LocalTalk operates at only 230 Kbps (or .23 Mbps).
Fig.2. LocalTalk connectors
Ethernet Cards vs. LocalTalk Connections
Ethernet LocalTalk
Fast data transfer (10 to 100 Mbps) Slow data transfer (.23 Mbps)
Expensive - purchased separately Built into Macintosh computers
Requires computer slot No computer slot necessary
Available for most computers Works only on Macintosh computers
Token Ring Cards
Token Ring network cards look similar to Ethernet cards. One visible difference is the type of connector on the back end of the card. Token Ring cards generally have a nine pin DIN type connector to attach the card to the network cable.
Switch
A concentrator is a device that provides a central connection point for cables from workstations, servers, and peripherals. In a star topology, twisted-pair wire is run from each workstation to a central switch/hub. Most switches are active, that is they electrically amplify the signal as it moves from one device to another. Switches no longer broadcast network packets as hubs did in the past, they memorize addressing of computers and send the information to the correct location directly. Switches are:
* Usually configured with 8, 12, or 24 RJ-45 ports
* Often used in a star or star-wired ring topology
* Sold with specialized software for port management
* Also called hubs
* Usually installed in a standardized metal rack that also may store netmodems, bridges, or routers
Repeaters
Since a signal loses strength as it passes along a cable, it is often necessary to boost the signal with a device called a repeater. The repeater electrically amplifies the signal it receives and rebroadcasts it. Repeaters can be separate devices or they can be incorporated into a concentrator. They are used when the total length of your network cable exceeds the standards set for the type of cable being used.
A good example of the use of repeaters would be in a local area network using a star topology with unshielded twisted-pair cabling. The length limit for unshielded twisted-pair cable is 100 meters. The most common configuration is for each workstation to be connected by twisted-pair cable to a multi-port active concentrator. The concentrator amplifies all the signals that pass through it allowing for the total length of cable on the network to exceed the 100 meter limit.
Bridges
A bridge is a device that allows you to segment a large network into two smaller, more efficient networks. If you are adding to an older wiring scheme and want the new network to be up-to-date, a bridge can connect the two.
A bridge monitors the information traffic on both sides of the network so that it can pass packets of information to the correct location. Most bridges can "listen" to the network and automatically figure out the address of each computer on both sides of the bridge. The bridge can inspect each message and, if necessary, broadcast it on the other side of the network.
The bridge manages the traffic to maintain optimum performance on both sides of the network. You might say that the bridge is like a traffic cop at a busy intersection during rush hour. It keeps information flowing on both sides of the network, but it does not allow unnecessary traffic through. Bridges can be used to connect different types of cabling, or physical topologies. They must, however, be used between networks with the same protocol.
Routers
A router translates information from one network to another; it is similar to a superintelligent bridge. Routers select the best path to route a message, based on the destination address and origin. The router can direct traffic to prevent head-on collisions, and is smart enough to know when to direct traffic along back roads and shortcuts.
While bridges know the addresses of all computers on each side of the network, routers know the addresses of computers, bridges, and other routers on the network. Routers can even "listen" to the entire network to determine which sections are busiest -- they can then redirect data around those sections until they clear up.
If you have a school LAN that you want to connect to the Internet, you will need to purchase a router. In this case, the router serves as the translator between the information on your LAN and the Internet. It also determines the best route to send the data over the Internet. Routers can:
* Direct signal traffic efficiently
* Route messages between any two protocols
* Route messages between linear bus, star, and star-wired ring topologies
* Route messages across fiber optic, coaxial, and twisted-pair cabling
Type rest of the post here
Netwotk Basic
One way to categorize the different types of computer network designs is by their scope or scale. For historical reasons, the networking industry refers to nearly every type of design as some kind of area network. Common examples of area network types are:
LAN and WAN were the original categories of area networks, while the others have gradually emerged over many years of technology evolution.
Note that these network types are a separate concept from network topologies such as bus, ring and star.
LAN - Local Area Network
A LAN connects network devices over a relatively short distance. A networked office building, school, or home usually contains a single LAN, though sometimes one building will contain a few small LANs (perhaps one per room), and occasionally a LAN will span a group of nearby buildings. In TCP/IP networking, a LAN is often but not always implemented as a single IP subnet.
In addition to operating in a limited space, LANs are also typically owned, controlled, and managed by a single person or organization. They also tend to use certain connectivity technologies, primarily Ethernet and Token Ring.
WAN - Wide Area Network
As the term implies, a WAN spans a large physical distance. The Internet is the largest WAN, spanning the Earth.
A WAN is a geographically-dispersed collection of LANs. A network device called a router connects LANs to a WAN. In IP networking, the router maintains both a LAN address and a WAN address.
A WAN differs from a LAN in several important ways. Most WANs (like the Internet) are not owned by any one organization but rather exist under collective or distributed ownership and management. WANs tend to use technology like ATM, Frame Relay and X.25 for connectivity over the longer distances.
LAN, WAN and Home Networking
Residences typically employ one LAN and connect to the Internet WAN via an Internet Service Provider (ISP) using a broadband modem. The ISP provides a WAN IP address to the modem, and all of the computers on the home network use LAN (so-called private) IP addresses. All computers on the home LAN can communicate directly with each other but must go through a central gateway, typically a broadband router, to reach the ISP.
Other Types of Area Networks
While LAN and WAN are by far the most popular network types mentioned, you may also commonly see references to these others:
- LAN - Local Area Network
- WLAN - Wireless Local Area Network
- WAN - Wide Area Network
- MAN - Metropolitan Area Network
- SAN - Storage Area Network, System Area Network, Server Area Network, or sometimes Small Area Network
- CAN - Campus Area Network, Controller Area Network, or sometimes Cluster Area Network
- PAN - Personal Area Network
- DAN - Desk Area Network
LAN and WAN were the original categories of area networks, while the others have gradually emerged over many years of technology evolution.
Note that these network types are a separate concept from network topologies such as bus, ring and star.
LAN - Local Area Network
A LAN connects network devices over a relatively short distance. A networked office building, school, or home usually contains a single LAN, though sometimes one building will contain a few small LANs (perhaps one per room), and occasionally a LAN will span a group of nearby buildings. In TCP/IP networking, a LAN is often but not always implemented as a single IP subnet.
In addition to operating in a limited space, LANs are also typically owned, controlled, and managed by a single person or organization. They also tend to use certain connectivity technologies, primarily Ethernet and Token Ring.
WAN - Wide Area Network
As the term implies, a WAN spans a large physical distance. The Internet is the largest WAN, spanning the Earth.
A WAN is a geographically-dispersed collection of LANs. A network device called a router connects LANs to a WAN. In IP networking, the router maintains both a LAN address and a WAN address.
A WAN differs from a LAN in several important ways. Most WANs (like the Internet) are not owned by any one organization but rather exist under collective or distributed ownership and management. WANs tend to use technology like ATM, Frame Relay and X.25 for connectivity over the longer distances.
LAN, WAN and Home Networking
Residences typically employ one LAN and connect to the Internet WAN via an Internet Service Provider (ISP) using a broadband modem. The ISP provides a WAN IP address to the modem, and all of the computers on the home network use LAN (so-called private) IP addresses. All computers on the home LAN can communicate directly with each other but must go through a central gateway, typically a broadband router, to reach the ISP.
Other Types of Area Networks
While LAN and WAN are by far the most popular network types mentioned, you may also commonly see references to these others:
- Wireless Local Area Network - a LAN based on WiFi wireless network technology
- Metropolitan Area Network - a network spanning a physical area larger than a LAN but smaller than a WAN, such as a city. A MAN is typically owned an operated by a single entity such as a government body or large corporation.
- Campus Area Network - a network spanning multiple LANs but smaller than a MAN, such as on a university or local business campus.
- Storage Area Network - connects servers to data storage devices through a technology like Fibre Channel.
- System Area Network - links high-performance computers with high-speed connections in a cluster configuration. Also known as Cluster Area Network.
Network Topologies
In computer networking, topology refers to the layout of connected devices. This article introduces the standard topologies of networking.
Topology in Network Design
Think of a topology as a network's virtual shape or structure. This shape does not necessarily correspond to the actual physical layout of the devices on the network. For example, the computers on a home LAN may be arranged in a circle in a family room, but it would be highly unlikely to find a ring topology there.
Network topologies are categorized into the following basic types:
* bus
* ring
* star
* tree
* mesh
More complex networks can be built as hybrids of two or more of the above basic topologies.
Bus Topology
Bus networks (not to be confused with the system bus of a computer) use a common backbone to connect all devices. A single cable, the backbone functions as a shared communication medium that devices attach or tap into with an interface connector. A device wanting to communicate with another device on the network sends a broadcast message onto the wire that all other devices see, but only the intended recipient actually accepts and processes the message.
Ethernet bus topologies are relatively easy to install and don't require much cabling compared to the alternatives. 10Base-2 ("ThinNet") and 10Base-5 ("ThickNet") both were popular Ethernet cabling options many years ago for bus topologies. However, bus networks work best with a limited number of devices. If more than a few dozen computers are added to a network bus, performance problems will likely result. In addition, if the backbone cable fails, the entire network effectively becomes unusable.
Ring Topology
In a ring network, every device has exactly two neighbors for communication purposes. All messages travel through a ring in the same direction (either "clockwise" or "counterclockwise"). A failure in any cable or device breaks the loop and can take down the entire network.
To implement a ring network, one typically uses FDDI, SONET, or Token Ring technology. Ring topologies are found in some office buildings or school campuses.
Star Topology
Many home networks use the star topology. A star network features a central connection point called a "hub" that may be a hub, switch or router. Devices typically connect to the hub with Unshielded Twisted Pair (UTP) Ethernet.
Compared to the bus topology, a star network generally requires more cable, but a failure in any star network cable will only take down one computer's network access and not the entire LAN. (If the hub fails, however, the entire network also fails.)
Tree Topology
Tree topologies integrate multiple star topologies together onto a bus. In its simplest form, only hub devices connect directly to the tree bus, and each hub functions as the "root" of a tree of devices. This bus/star hybrid approach supports future expandability of the network much better than a bus (limited in the number of devices due to the broadcast traffic it generates) or a star (limited by the number of hub connection points) alone.
Mesh Topology
Mesh topologies involve the concept of routes. Unlike each of the previous topologies, messages sent on a mesh network can take any of several possible paths from source to destination. (Recall that even in a ring, although two cable paths exist, messages can only travel in one direction.) Some WANs, most notably the Internet, employ mesh routing.
A mesh network in which every device connects to every other is called a full mesh. As shown in the illustration below, partial mesh networks also exist in which some devices connect only indirectly to others.
Summary
Topologies remain an important part of network design theory. You can probably build a home or small business computer network without understanding the difference between a bus design and a star design, but becoming familiar with the standard topologies gives you a better understanding of important networking concepts like hubs, broadcasts, and routes.
Topology in Network Design
Think of a topology as a network's virtual shape or structure. This shape does not necessarily correspond to the actual physical layout of the devices on the network. For example, the computers on a home LAN may be arranged in a circle in a family room, but it would be highly unlikely to find a ring topology there.
Network topologies are categorized into the following basic types:
* bus
* ring
* star
* tree
* mesh
More complex networks can be built as hybrids of two or more of the above basic topologies.
Bus Topology
Bus networks (not to be confused with the system bus of a computer) use a common backbone to connect all devices. A single cable, the backbone functions as a shared communication medium that devices attach or tap into with an interface connector. A device wanting to communicate with another device on the network sends a broadcast message onto the wire that all other devices see, but only the intended recipient actually accepts and processes the message.
Ethernet bus topologies are relatively easy to install and don't require much cabling compared to the alternatives. 10Base-2 ("ThinNet") and 10Base-5 ("ThickNet") both were popular Ethernet cabling options many years ago for bus topologies. However, bus networks work best with a limited number of devices. If more than a few dozen computers are added to a network bus, performance problems will likely result. In addition, if the backbone cable fails, the entire network effectively becomes unusable.
Ring Topology
In a ring network, every device has exactly two neighbors for communication purposes. All messages travel through a ring in the same direction (either "clockwise" or "counterclockwise"). A failure in any cable or device breaks the loop and can take down the entire network.
To implement a ring network, one typically uses FDDI, SONET, or Token Ring technology. Ring topologies are found in some office buildings or school campuses.
Star Topology
Many home networks use the star topology. A star network features a central connection point called a "hub" that may be a hub, switch or router. Devices typically connect to the hub with Unshielded Twisted Pair (UTP) Ethernet.
Compared to the bus topology, a star network generally requires more cable, but a failure in any star network cable will only take down one computer's network access and not the entire LAN. (If the hub fails, however, the entire network also fails.)
Tree Topology
Tree topologies integrate multiple star topologies together onto a bus. In its simplest form, only hub devices connect directly to the tree bus, and each hub functions as the "root" of a tree of devices. This bus/star hybrid approach supports future expandability of the network much better than a bus (limited in the number of devices due to the broadcast traffic it generates) or a star (limited by the number of hub connection points) alone.
Mesh Topology
Mesh topologies involve the concept of routes. Unlike each of the previous topologies, messages sent on a mesh network can take any of several possible paths from source to destination. (Recall that even in a ring, although two cable paths exist, messages can only travel in one direction.) Some WANs, most notably the Internet, employ mesh routing.
A mesh network in which every device connects to every other is called a full mesh. As shown in the illustration below, partial mesh networks also exist in which some devices connect only indirectly to others.
Summary
Topologies remain an important part of network design theory. You can probably build a home or small business computer network without understanding the difference between a bus design and a star design, but becoming familiar with the standard topologies gives you a better understanding of important networking concepts like hubs, broadcasts, and routes.
Free AdSense e-Books
Just share from other website
Here three e-Books of Google AdSense that you can get for free:
* AdSense SEO
* TripleYour AdSense CTR
* AdSense Tips
You can see some video tips about Google Adsense at Michael Cheney's Adsense Clinic site and get some adsense tips for your blog at Making Money 4 Free.
Read and good luck friend!
from : http://linuxmini.blogspot.com
Student Loan Consolidation
Student loan consolidation is one of the most used methods for reducing and working off student debt. If you want to consolidate debt, whether it's a student loan debt or not, you have to follow a certain process. However, this process is easy to follow and will absolutely not require big efforts from your side.
Here is what you have to know about the consolidation process: You combine all of your various student loans into one large loan. Instead of paying toward all your loans each month, you make one payment towards this one loan. So, what will I gain with this, you may ask. If you compare the numbers before and after you have consolidated your student debt, you'll understand that it's a very good deal.
To start out the working career with an overwhelming amount of debt is a daunting prospect to put it mildly. But the fact is that many college graduates unfortunately are facing this situation. Fortunately consolidating your student loans is a great way to meet the challenge of getting rid of the burden of debt from school or college.
The main benefit of consolidation is that you'll normally pay a lower interest rate then compared to what your various loans are already set at. This works the same way as refinancing a home in order to have a lower mortgage payment. And be aware of the fact that the current interest rate is the lowest it has been in almost 40 years. When you do a consolidation you'll pay one interest rate, not several different rates. And at the time you took these loans, the rates were probably higher.
And this means money saved: A lower interest rate on a relatively big loan can save you thousands of dollars in the long run. And in addition to this, some lending companies offer rate reductions for students consolidating their loans while they are in their grace period. A warning though: Stay away from companies that require you to start your payment immediately after the grace period. There are financing companies out there that don't require this. Go to them!!!
And as if this wasn't enough, some companies even offer additional rate reductions. I have heard about companies that reduce your rate by one percent if you make all of your payments on time for two years. And this comes in addition to the discounts described above. One percent may seem small, but if you see it in a perspective of, let's say 20 years, which is a normal payback schedule, it can mean lots of dollars saved.
Another benefit with student debt consolidation is saving time and effort. It's much easier to handle one payment monthly than several separate payments.
A convenient way to do the monthly payments is to let the loan company deduct it directly from your bank account. Some companies allow that. And if it is a really good student loan consolidation, it will even give you a little interest rate reduction by handling your loan payments this way.
So, if you find that loan consolidation is (in) for you, your challenge is to decide which loan consolidation company to approach and finally select. What I would recommend is that you make a list of all the questions you might have, call a few companies and speak with their representatives. Or you can go online to find a good student loan consolidation company. There are some great companies out there.
http://www.articlesbase.com
Here is what you have to know about the consolidation process: You combine all of your various student loans into one large loan. Instead of paying toward all your loans each month, you make one payment towards this one loan. So, what will I gain with this, you may ask. If you compare the numbers before and after you have consolidated your student debt, you'll understand that it's a very good deal.
To start out the working career with an overwhelming amount of debt is a daunting prospect to put it mildly. But the fact is that many college graduates unfortunately are facing this situation. Fortunately consolidating your student loans is a great way to meet the challenge of getting rid of the burden of debt from school or college.
The main benefit of consolidation is that you'll normally pay a lower interest rate then compared to what your various loans are already set at. This works the same way as refinancing a home in order to have a lower mortgage payment. And be aware of the fact that the current interest rate is the lowest it has been in almost 40 years. When you do a consolidation you'll pay one interest rate, not several different rates. And at the time you took these loans, the rates were probably higher.
And this means money saved: A lower interest rate on a relatively big loan can save you thousands of dollars in the long run. And in addition to this, some lending companies offer rate reductions for students consolidating their loans while they are in their grace period. A warning though: Stay away from companies that require you to start your payment immediately after the grace period. There are financing companies out there that don't require this. Go to them!!!
And as if this wasn't enough, some companies even offer additional rate reductions. I have heard about companies that reduce your rate by one percent if you make all of your payments on time for two years. And this comes in addition to the discounts described above. One percent may seem small, but if you see it in a perspective of, let's say 20 years, which is a normal payback schedule, it can mean lots of dollars saved.
Another benefit with student debt consolidation is saving time and effort. It's much easier to handle one payment monthly than several separate payments.
A convenient way to do the monthly payments is to let the loan company deduct it directly from your bank account. Some companies allow that. And if it is a really good student loan consolidation, it will even give you a little interest rate reduction by handling your loan payments this way.
So, if you find that loan consolidation is (in) for you, your challenge is to decide which loan consolidation company to approach and finally select. What I would recommend is that you make a list of all the questions you might have, call a few companies and speak with their representatives. Or you can go online to find a good student loan consolidation company. There are some great companies out there.
http://www.articlesbase.com
Football Manager 2009
Popular Game strategy soccer like Football Manager (FM) trust significantly in the newest version, FM 2009. This scene is presented with the American game 3-dimensional pattern.
Later, the team's football game at FM 2009 will appear in 3 dimensions with a choice of various camera angles in the field. And for those who still want to play version 2 dimension, FM 2009 still presents options.
Other major enhancements is that more interaction between managers with the assistant manager. The assistants will be able to comment on the appearance of the players and whether the tactics that successfully prepared, at the time the match is still ongoing.
There's more gelontoran new features in FM 2009. Among them, the players can do a press conference with local or national media. As the manager can also relationships with journalists who want the ball
The FM programming team also improve the transfer system so that players feel more authentic and realistic.
there are spesifcation of Computer you need
OS: Windows XP or Vista
Processor: XP: 1.4GHz or Faster / Vista: 2.0GHz or Faster
Supported Processors: Intel Pentium 4, Intel Core, AMD Athlon
Memory: XP: 512MB RAM / Vista: 1.0GB RAM
Hard Drive Space: 2GB
DVD-Drive: 4x Speed
Video Card: 128MB *Supported Chipsets (see below)
Sound Card: DirectX 9.0c compatible
Directx: Version 9.0c (included)
LAN: TCP/IP compliant
Input: Keyboard, Mouse
Supported Chipsets Nvidia FX 5900 Ultra or greater; ATI Radeon 9800 or
greater; Intel 82915G/82910GL or greater.
Earlier cards may only display 2D Match Viewer Mode and are not supported.
Laptop versions of these chipsets may work but are not supported.
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