We all do dumb things now and then, and computer users are no exception. Inadvertently pressing the wrong key combination or innocently clicking OK in the wrong dialog box can change important settings that alter a computer's behavior or even crash the system.
Nervous newbies are often fearful that one wrong move might break the computer forever. Luckily, short of taking a sledge hammer to the box, the consequences aren't usually quite that dire. Even so, users often do create problems for their computers and for your network. Here's a description of common missteps you can share with your users to help them steer clear of preventable problems.
#1: Plug into the wall without surge protection
Here's one that actually can physically destroy your computer equipment, as well as the data it holds. You may think your systems are in danger only during an electrical storm, but anything that interrupts the electrical circuit and then starts the current back again can fry your components. Something as simple as someone turning on an appliance that's plugged into the same circuit (especially a high voltage one such as a hair dryer, electric heater, or air conditioner) can cause a surge, or a surge may be caused by a tree limb touching a power line. If you have a power outage, you may experience a surge when the electricity comes back on.
You can protect your systems against damage from power surges by always using a surge protector, but it's important to be aware that most cheap surge protectors will survive only a single surge and need to be replaced afterward. An Uninterruptible Power Supply (UPS) is better than a surge protector; it has a battery that keeps power flowing smoothly even when there's an outage, to give you time to gracefully shut down.
#2: Surf the Internet without a firewall
Many home users plug their computers right into their spiffy new cable or DSL modems and hop onto the Internet without realizing that they're putting themselves at risk from viruses and attackers. Every Internet-connected computer should be protected by a firewall; this can be a firewall built into the broadband modem or router, a separate firewall appliance that sits between the modem/router and the computer, a server at the network's edge running firewall software, or personal firewall software installed on the computer.
One advantage of personal firewalls on laptop computers is that they're still with you when you take the computer on the road and plug into a hotel's DSL or cable port or connect to a wireless hotspot. Just having a firewall isn't enough, though. You must also be sure it's turned on and configured properly to protect you.
#3: Neglect to run or update antivirus and anti-spyware programs
Let's face it: Antivirus programs can be a royal pain. They're always blocking some application you want to use, you often have to disable them to install new software, and they have to be updated on a regular basis to do any good. Seems like the subscription is always expiring and prompting you to renew it--for a fee, in many cases. But in today's environment, you can't afford to go without virus protection. The malicious programs that AV software detects--viruses, Trojans, worms, etc.--can not only wreak havoc on your system but can spread via your computer to the rest of the network. In extreme cases, they can bring down the whole network.
Spyware is another growing threat; these are programs that install themselves on your computer (usually without your knowledge) and collect information from your system that is then sent back to the spyware program's author or vendor. Antivirus programs often don't address spyware so it's important to run a dedicated spyware detection and removal program.
#4: Install and uninstall lots of programs, especially betas
You like to be on the cutting edge, so you often install and try out new software. Beta programs are usually free and give you a chance to sample neat new features before most people. There are also many freeware and shareware programs made available as Internet downloads by their authors. We know you'd never do it, but some users even install pirated software or "warez."
The more programs you install, the more likely you are to run across ones that either include malicious code or that are poorly written and cause your system to behave improperly or crash. The risk is greater with pirated programs.
Even if you install only licensed, final-release commercial software, too many installations and uninstallations can gunk up the registry. Not all uninstall routines completely remove program remnants and at the least, this practice can cause your system to slow down over time.
You should install only the programs that you really need, stick with legitimate software, and try to minimize the number you install and uninstall.
#5: Keep disks full and fragmented
One of the results of installing and uninstalling lots of programs (or adding and deleting data of any kind) is that it fragments your disk. Disk fragmentation occurs because of the way information is stored on the disk: On a new, clean disk, when you save a file it's stored in contiguous sections called clusters. If you delete a file that takes up, for example, five clusters, and then save a new file that takes eight clusters, the first five clusters' worth of data will be saved in the empty space left by the deletion and the remaining three will be saved in the next empty spaces. That makes the file fragmented, or divided. To access that file, then, the disk's read heads won't find all the parts of the file together but must go to different locations on the disk to retrieve it all. That makes it slower to access. If the file is part of a program, the program will run more slowly. A badly fragmented disk will slow down to a crawl.
You can use the disk defragmenter built into Windows (Programs Accessories System Tools) or a third-party defrag program to rearrange these pieces of files so that they're placed contiguously on the disk.
Another common cause of performance problems and application misbehavior is a disk that's too full. Many programs create temporary files and need extra free space on the disk to operate. You can use Windows XP's Disk Cleanup Tool or a third-party program to find and delete rarely used files, or you can manually delete files to clear space on your disk.
#6: Open all attachments
Some folks just can't help themselves: Getting an e-mail message with an attachment is like getting an unexpected gift. You just have to peek inside to see what it is. But just as that package left on your doorstep could contain a bomb, that file attached to your mail message could contain code that will delete your documents or system folder or send viruses to everyone in your address book.
The most blatantly dangerous attachments are executable files--those that run code--with extensions like .exe, .cmd, and many others. Files that aren't themselves executables, such as Word .doc files and Excel .xls files, can contain embedded macros. Scripts (Visual Basic, JavaScript, Flash, etc.) aren't directly executed by the computer but are run by other programs.
It used to be that you could assume plain text (.txt) or graphics (.gif, .jpg, .bmp) files were safe, but not anymore. File extensions can be spoofed; attackers take advantage of the Windows default setting that doesn't display common file extensions to name executables something like greatfile.jpg.exe. With the real extension hidden, it shows up as greatfile.jpg. So the recipient thinks it's a graphic, but it's actually a malicious program.
You should open attachments only when they're from trusted sources and only when you're expecting them. Even if the mail with the attachment appears to come from someone you trust, it's possible that someone spoofed their address or that their computer is infected with a virus that sent the attachment to you without their knowledge.
#7: Click on everything
Opening attachments isn't the only type of mouse click that can get you in trouble. Clicking on hyperlinks in e-mail messages or on Web pages can take you to Web sites that have embedded ActiveX controls or scripts that can perform all sorts of malicious activities, from wiping your hard disk to installing a backdoor program on your computer that a hacker can use to get in and take control of it.
Clicking the wrong link can also take you to inappropriate Web sites that feature pornography, pirated music or software, or other content that can get you in trouble if you're using a computer on the job or even get you in trouble with the law.
Don't give in to "click mania." Think before you click a link. Links can also be disguised in phishing messages or on Web sites to appear to take you to a different site from the ones they really point to. For example, the link might say www.safesite.com, but it actually takes you to www.gotcha.com. You can often find out the real URL by hovering over the link without clicking it.
#8: Share and share alike
Your mother taught you that it's nice to share, but when you're on a network, sharing can expose you to dangers. If you have file and printer sharing enabled, others can remotely connect to your computer and access your data. Even if you haven't created any shared folders, by default Windows systems have hidden "administrative" shares for the root of each drive. A savvy hacker may be able to use these shares to get in. One way to prevent that is to turn off file and printer sharing--if you don't need to make any of the files on your computer accessible across the network. This is especially a good idea if you're connecting your laptop to a public wireless hotspot. If you do need to make shared folders accessible, it's important that they be protected by both share-level permissions and file-level (NTFS) permissions. Also ensure that your account and the local administrative account have strong passwords.
#9: Pick the wrong passwords
That brings us to another common mistake that can expose you to attacks: picking the wrong password. Even if you don't belong to a network where the administrator forces you to select strong passwords and change them regularly, you should do so. Don't pick passwords that are easy to guess, such as your birthdate, loved one's name, social security number, etc. Longer passwords are harder to crack, so make your password at least eight characters long; 14 is even better. Popular password-cracking methods use "dictionary" attacks, so don't use words that are in the dictionary. Passwords should contain a combination of alpha, numeric, and symbol characters for best security.
A long string of nonsense characters may create a password that's tough to crack, but if you can't remember it, you'll defeat the purpose by writing it down (where an intruder may be able to find it). Instead, create a phrase you can remember easily and use the first letters of each word, along with logical numbers and symbols. For example: "My cat ate a mouse on the 5th day of June" becomes "Mc8amot5doJ."
#10: Ignore the need for a backup and recovery plan
Even if you follow all these suggestions, an attacker may crash your system or your data may be corrupted or get wiped out by a hardware problem. That's why it's essential that you always back up your important information and have a plan for recovering from a system failure.
Most computer users know they should back up, but many never get around to it. Or they make an initial backup but don't update it regularly. Use the built-in Windows backup program (Ntbackup.exe in Windows NT, 2000, and XP) or a third-party backup program and schedule backups to occur automatically. Store backed up data on a network server or removable drive in a location away from the computer itself, in case of a natural disaster like flood, fire, or tornado.
Remember that the data is the most important thing on your computer. The operating system can be reinstalled and so can applications, but it may be difficult or impossible to recreate your original data.
Nonetheless, you can save time and frustration by backing up your system information too. You can create mirror images of your disks using popular ghost or clone programs. This will allow you to restore the system quickly instead of going through the tedious installation process.
Showing posts with label IT. Show all posts
Showing posts with label IT. Show all posts
Tuesday, June 24, 2008
Monday, June 16, 2008
Computer Maintenance
I do the following cleanup and scans at least once a week.
Most or all of the newer Windows operating systems come with their own firewall, cleanup, and disk defragment utilities. You can access them via the start button in the lower left corner of the task bar at the bottom of the desktop. For the firewall, from start go to Control Panel and double left click the Security Center Icon. It will show if the firewall is on, your virus protection and if automatic updates is on. Automatic updates can be scheduled for user convenience. These are critical updates from the Microsoft site. Most of them fix security issues to prevent hackers and fix security bugs. Scheduling Automatic Updates is very highly recommended.
The best virus protection I have found is AVG (AVG.com). They do offer a free program that I used for years. A highly trained support technician advised me of it after my computer was hacked. I liked and trusted it so much, that I have just purchased my second 2-year license because it offers more real time protection and is easy to use. It is also very reasonably priced. I tried McAffee for a while, but it did not have all of what I was looking for. I initially used Norton Anti-virus until a hacker was able to shut it down and give me a virus. Norton has too many bells and unnecessary whistles for my liking, and I found it very difficult to uninstall. It seems to wind its way into everything.
To access the operating system's maintenance utilities, again go to start and click All Programs in the menu on the left. Then go to Accessories, then System Tools. I do the Disk Cleanup for C: first. Be careful of what is checked in this tool, as you do not want to delete any needed files. Several years ago, I was not so knowledgeable and checked for it to clean up my Office Setup Files. I lost them, and I needed them.
When you click the Cleanup box that pops up, it will check to see what needs cleaned up and then show you a list of files to take care of. These are the ones to check: downloaded program files, temporary internet files, offline webpages, Microsoft Office Temporary files, recycle bin, web client/publisher temporary files, and compress old files. This is washing away the junk that will lug your system way down.
The other tool that should be done at least weekly is the Disk Defragmenter. Access it the same way you access the Cleanup tool. Be sure that the Disk C: is what will be defragmented. The other disk is your recovery disk, and since you do not do anything with it, it does not need work. Leave it alone. Defragmenting helps keep all files for each program together in one place, so the brain does not have to search for things. Fragmented drives run very slowly.
Those are the basic steps to keeping the Windows systems in good shape. I also do weekly scans with the free versions of Spybot Search and Destroy and Adaware. The most trusted site to get them is CNet.com, downloads, search for Free Spybot Search and Destroy, then search for Free Adaware. You will need to read the readme files to make sure you understand how to set the settings and whether to remove certain items or not. They will scan for things like adware and tracking cookies that we get from surfing the web.
Most or all of the newer Windows operating systems come with their own firewall, cleanup, and disk defragment utilities. You can access them via the start button in the lower left corner of the task bar at the bottom of the desktop. For the firewall, from start go to Control Panel and double left click the Security Center Icon. It will show if the firewall is on, your virus protection and if automatic updates is on. Automatic updates can be scheduled for user convenience. These are critical updates from the Microsoft site. Most of them fix security issues to prevent hackers and fix security bugs. Scheduling Automatic Updates is very highly recommended.
The best virus protection I have found is AVG (AVG.com). They do offer a free program that I used for years. A highly trained support technician advised me of it after my computer was hacked. I liked and trusted it so much, that I have just purchased my second 2-year license because it offers more real time protection and is easy to use. It is also very reasonably priced. I tried McAffee for a while, but it did not have all of what I was looking for. I initially used Norton Anti-virus until a hacker was able to shut it down and give me a virus. Norton has too many bells and unnecessary whistles for my liking, and I found it very difficult to uninstall. It seems to wind its way into everything.
To access the operating system's maintenance utilities, again go to start and click All Programs in the menu on the left. Then go to Accessories, then System Tools. I do the Disk Cleanup for C: first. Be careful of what is checked in this tool, as you do not want to delete any needed files. Several years ago, I was not so knowledgeable and checked for it to clean up my Office Setup Files. I lost them, and I needed them.
When you click the Cleanup box that pops up, it will check to see what needs cleaned up and then show you a list of files to take care of. These are the ones to check: downloaded program files, temporary internet files, offline webpages, Microsoft Office Temporary files, recycle bin, web client/publisher temporary files, and compress old files. This is washing away the junk that will lug your system way down.
The other tool that should be done at least weekly is the Disk Defragmenter. Access it the same way you access the Cleanup tool. Be sure that the Disk C: is what will be defragmented. The other disk is your recovery disk, and since you do not do anything with it, it does not need work. Leave it alone. Defragmenting helps keep all files for each program together in one place, so the brain does not have to search for things. Fragmented drives run very slowly.
Those are the basic steps to keeping the Windows systems in good shape. I also do weekly scans with the free versions of Spybot Search and Destroy and Adaware. The most trusted site to get them is CNet.com, downloads, search for Free Spybot Search and Destroy, then search for Free Adaware. You will need to read the readme files to make sure you understand how to set the settings and whether to remove certain items or not. They will scan for things like adware and tracking cookies that we get from surfing the web.
Wednesday, June 11, 2008
Computer Terminology
Computer Terminology Is An Alien Language
Memory or RAM:Memory or RAM is your work bench. It is where the work gets done. The more memory you have, the more things you can do at the same time. Ram is measured in mega (mega= million) bytes.
CPU or ProcessorYour CPU or Processor is your motor. The more powerful your motor, the faster you can get things done. Processor speed is measured in GHZ or giga (Giga= A million million) hertz.
Hard DriveThe Hard Drive is your file cabinet, the more data you can save for future use. Hard Drive space is measured in mb or mega (millions of) bytes.
See? Nothing mystical about those terms is there?
Now on to the Definitions.
Definitions
Adware Those unwanted ads that appear on your browser.
Software that can detect and block viruses from entering your computer. It is vital that you have this and run it regularly to protect your data.
Bit A Single piece of data.
Byte A block of bits, usually 8 bits. An example of a byte would be a single letter as "A".
Browser The software that helps find what you are looking when you surf the internet.
Computer A high speed moron. It does exactly what it is told. This is not necessarily what you want it to do.
CPU Central Processing Unit. This is the heart, engine, motor of your computer.
DVD+R A format used to burn a DVD. Usually not compatible with a DVD-R drive.
DVD-R A format used to burn a DVD. Usually not compatible with a DVD+R drive.
Firewall A vital device that can be either software or hardware that hides your computer from the outside world. Windows has a built in firewall.
Firewire A type of connection to a computer. Used for connecting a device such as a camcorder to a PC. It is also known as IEEE1394. Sony calls their version "I-link".
Floppy disk A type of storage media. Floppies are no longer popular due to the limited capacity and slow speed.
Gamer A person that uses a PC primarily for playing video games. It requires a fast PC and a high level graphics card.
GHZ Giga hertz. Abbreviated as ghz. This is the speed of a processor. A hertz is a cycle.
Gigabyte A billion (thousand million) bytes of data.
Graphics Processor The component that processes and sends images to the monitor. Many demanding programs use the graphics processor as an additional processor to help the main CPU.
Hard Drive A storage unit. The hard drive is where data or applications are stored until needed again. It has non destructive readout meaning reading it does not destroy the data as in RAM.
Hi-Def High Definition as in TV. It is a very high resolution device and requires a lot of storage space.
IEEE1394 A type of connection to a computer. It is usually used by digital camcorders or external hard drives. Also known as "Firewire".
Internet The internet is a superhighway with information at waypoints scattered everywhere. In order to find where you are going, you need a browser, a url or a search engine such as Google or Yahoo.
LAN Local area network. The connection of several PCs together. They can also share an internet connection. An example of a LAN would be the 3 PCs in my house connected together. Data can be shared between the PCs.
Megabyte A million bytes of data.
Memory Also known as RAM. It is where data and programs are kept whle working or being worked upon. It is a destructive readout deivce, meaning that if you want to keep it, you must restore it. This is a concern only for programmers not users.
OS OS stands for operating system. Windows and Linux are examples of operating systems.
Processor The unit that does the work in a computer. Also known as CPU.
RAM Ram stands for random access memory. Random because you can pull data from any address, not wait flr sequential as in a hard drive.
Ram Drive A very fast retrieval device for storage. It uses memory as its media, where as a disk uses a metallic storage.
Router A device for connecting to the network. It allows several PCs to share a single network connection.
Scanner A peripheral device for reading a document, converting to a digital data stream and sending it to the computer.
Software A compilation of instructions to the processor telling it what to do in order to complete its taks. Remember, the high speed moron does only what it is told.
Spyware A snippet of instructions that is stored on your hardware without your knowledge. It then reports back to its originator what you are doing. Anti-spyware software can prevent this.
Switch A device used in a network. It usually has a router integrated into it. It also is an excellent firewall.
Terabyte Terabyte is a million million. That is a "1" followed by 12 "0"s.
Trojan Horse A snippet of software (usually malicious) that gets into your computer as a part of a legitimate message, such as email. Once activated, it can wreak havoc, even ruining a hard drive. Most anti-virus software also blocks trojans.
USB Universal Serial Bus (USB) is a type of connection to your PC. It is used to connect devices to your PC.
Virus A virus is a piece of malicious that enters your computer, usually against your knowledge that can corrupt your hard drive and thus your data.
Virus Checker Software that blocks viruses from entering your PC. Also known as anti-virus software.
Vista Vista is the latest operating system (OS) from Microsoft.
WAN Wide area network. Usually a connection of systems in several locations off the main premise or campus. For example, if you work at a company that has several locations in various cities that are connected via high speed lines, this is a WAN.
Web cam A small camera that is connected to your PC via USB or firewire can record what is going on within its view and send to your PC. From there, you can allow relatives in another location to view what is going on at your home.
Wireless In computerese, a method of connecting several PC's together. Each computer would require a wireless adapter. Routers and switches can offer a wireless connections. This eliminates the need to run cables between the various units.
Worm A snippet of programming language that is covertly slipped into your computer. When activated, it can corrupt your files, take over your browser, etc. Generally, anti virus software blocks worms.
WYSIWYG What you see is what you get. In other words, this is how your output will look.
XP Microsoft Windows operating system. XP is the predecessor to Vista.
Memory or RAM:Memory or RAM is your work bench. It is where the work gets done. The more memory you have, the more things you can do at the same time. Ram is measured in mega (mega= million) bytes.
CPU or ProcessorYour CPU or Processor is your motor. The more powerful your motor, the faster you can get things done. Processor speed is measured in GHZ or giga (Giga= A million million) hertz.
Hard DriveThe Hard Drive is your file cabinet, the more data you can save for future use. Hard Drive space is measured in mb or mega (millions of) bytes.
See? Nothing mystical about those terms is there?
Now on to the Definitions.
Definitions
Adware Those unwanted ads that appear on your browser.
Software that can detect and block viruses from entering your computer. It is vital that you have this and run it regularly to protect your data.
Bit A Single piece of data.
Byte A block of bits, usually 8 bits. An example of a byte would be a single letter as "A".
Browser The software that helps find what you are looking when you surf the internet.
Computer A high speed moron. It does exactly what it is told. This is not necessarily what you want it to do.
CPU Central Processing Unit. This is the heart, engine, motor of your computer.
DVD+R A format used to burn a DVD. Usually not compatible with a DVD-R drive.
DVD-R A format used to burn a DVD. Usually not compatible with a DVD+R drive.
Firewall A vital device that can be either software or hardware that hides your computer from the outside world. Windows has a built in firewall.
Firewire A type of connection to a computer. Used for connecting a device such as a camcorder to a PC. It is also known as IEEE1394. Sony calls their version "I-link".
Floppy disk A type of storage media. Floppies are no longer popular due to the limited capacity and slow speed.
Gamer A person that uses a PC primarily for playing video games. It requires a fast PC and a high level graphics card.
GHZ Giga hertz. Abbreviated as ghz. This is the speed of a processor. A hertz is a cycle.
Gigabyte A billion (thousand million) bytes of data.
Graphics Processor The component that processes and sends images to the monitor. Many demanding programs use the graphics processor as an additional processor to help the main CPU.
Hard Drive A storage unit. The hard drive is where data or applications are stored until needed again. It has non destructive readout meaning reading it does not destroy the data as in RAM.
Hi-Def High Definition as in TV. It is a very high resolution device and requires a lot of storage space.
IEEE1394 A type of connection to a computer. It is usually used by digital camcorders or external hard drives. Also known as "Firewire".
Internet The internet is a superhighway with information at waypoints scattered everywhere. In order to find where you are going, you need a browser, a url or a search engine such as Google or Yahoo.
LAN Local area network. The connection of several PCs together. They can also share an internet connection. An example of a LAN would be the 3 PCs in my house connected together. Data can be shared between the PCs.
Megabyte A million bytes of data.
Memory Also known as RAM. It is where data and programs are kept whle working or being worked upon. It is a destructive readout deivce, meaning that if you want to keep it, you must restore it. This is a concern only for programmers not users.
OS OS stands for operating system. Windows and Linux are examples of operating systems.
Processor The unit that does the work in a computer. Also known as CPU.
RAM Ram stands for random access memory. Random because you can pull data from any address, not wait flr sequential as in a hard drive.
Ram Drive A very fast retrieval device for storage. It uses memory as its media, where as a disk uses a metallic storage.
Router A device for connecting to the network. It allows several PCs to share a single network connection.
Scanner A peripheral device for reading a document, converting to a digital data stream and sending it to the computer.
Software A compilation of instructions to the processor telling it what to do in order to complete its taks. Remember, the high speed moron does only what it is told.
Spyware A snippet of instructions that is stored on your hardware without your knowledge. It then reports back to its originator what you are doing. Anti-spyware software can prevent this.
Switch A device used in a network. It usually has a router integrated into it. It also is an excellent firewall.
Terabyte Terabyte is a million million. That is a "1" followed by 12 "0"s.
Trojan Horse A snippet of software (usually malicious) that gets into your computer as a part of a legitimate message, such as email. Once activated, it can wreak havoc, even ruining a hard drive. Most anti-virus software also blocks trojans.
USB Universal Serial Bus (USB) is a type of connection to your PC. It is used to connect devices to your PC.
Virus A virus is a piece of malicious that enters your computer, usually against your knowledge that can corrupt your hard drive and thus your data.
Virus Checker Software that blocks viruses from entering your PC. Also known as anti-virus software.
Vista Vista is the latest operating system (OS) from Microsoft.
WAN Wide area network. Usually a connection of systems in several locations off the main premise or campus. For example, if you work at a company that has several locations in various cities that are connected via high speed lines, this is a WAN.
Web cam A small camera that is connected to your PC via USB or firewire can record what is going on within its view and send to your PC. From there, you can allow relatives in another location to view what is going on at your home.
Wireless In computerese, a method of connecting several PC's together. Each computer would require a wireless adapter. Routers and switches can offer a wireless connections. This eliminates the need to run cables between the various units.
Worm A snippet of programming language that is covertly slipped into your computer. When activated, it can corrupt your files, take over your browser, etc. Generally, anti virus software blocks worms.
WYSIWYG What you see is what you get. In other words, this is how your output will look.
XP Microsoft Windows operating system. XP is the predecessor to Vista.
What id WAN??
Types and Characteristics of WANs
What is a WAN?
There are two prevailing definitions of a Wide Area Network (WAN). The book definition of a WAN is a network that spans large geographical locations, usually to interconnect multiple Local Area Networks (LANs). The practical definition of a WAN is a network that traverses a public network or commercial carrier, using one of several WAN technologies
What are its Main Components?
The main components for a WAN are routers, switches and modems. These components are described below in the hardware section.
CPE - Devices on the subscriber premises are called customer premises equipment (CPE). The subscriber owns the CPE or leases the CPE from the service provider. A copper or fiber cable connects the CPE to the service provider's nearest exchange or central office. This cabling is often called the local loop, or "last-mile".
DTE/DCE - Devices that put data on the local loop are called data circuit-terminating equipment, or data communications equipment (DCE). The customer devices that pass the data to the DCE are called data terminal equipment (DTE). The DCE primarily provides an interface for the DTE into the communication link on the WAN cloud.
HardwareIn a WAN you will need various types of hardware components for it to function. The typical items of hardware that you will need in a WAN are:
Router - An electronic device that connects a local area network (LAN) to a wide area network (WAN) and handles the task of routing messages between the two networks. Operates at layer 3, and makes decisions using IP addresses.
Switch - A switch is a network device that selects a path or circuit for sending a unit of data to its next destination. Operates at layer 2, and uses MAC addresses to send data to correct destination.
Modem - Short for modulator/demodulator, a modem enables a computer to communicate with other computers over telephone lines. Operates at layer 1, where signals are converted from digital to analogue and vice versa for transmission and receiving.
Wan Standards
WANs operate within the OSI model using layer 1 and layer 2 levels. The data link layer and the physical layer. The physical layer protocols describe how to provide electrical, mechanical and functional connections to the services provided by the ISP. The data link layer defines how data is encapsulated for transmission to remote sites.
Encapsulation
Encapsulation is the wrapping of data in a particular protocol header. Remember that WANs operate at the physical layer and the data link layer of the osi model and that higher layer protocols such as IP are encapsulated when sent across the WAN link. Serial interfaces support a wide range of WAN encapsulation types, which must be manually specified. These types include SDLC, PPP, Frame delay etc. Regardless of WAN encapsulation used it must be identical on both sides of the point to point link.
Packet and Circuit Switching
Circuit switching and packet switching are both used in high-capacity networks. The majority of switched networks today get data across the network through packet switching.
Circuit-switching is more reliable than packet-switching. Circuit switching is old and expensive, packet switching is more modern.
General Routing Issues
What is a Routing Protocol?
A routing protocol is a protocol that specifies how routers communicate and exchange information on a network. Each router has prior knowledge of its immediate neighbours and knows the structure of the network topology. The routers know this because the routing protocol shares this information.
Protocol
RIP (Routing Information Protocol) was one of the most commonly uses protocols on internal networks. Routers use RIP to dynamically adapt changes to the network connections and communicate information about which networks routers can reach and the distance between them. RIP is sometimes said to stand for Rest in Pieces in reference to the reputation that RIP has for breaking unexpectedly and rendering a network unable to function.
Routing Algorithms
Distance Vector
This type of routing protocol requires that each router simply inform its neighbours of its routing table. The distance vector protocol is also known as the bellman-ford algorithm.
Link State
This type of routing protocol requires that each router maintain a partial map of the network. The link state algorithm is also know as Dijkstra's algorithm.
IGRP
IGRP is a type of distance vector routing protocol invented by cisco used to exchange routing data in a autonomous system. Distance vector protocols measure distances and compare routes. Routers that use distance vector must send all or a portion of their routing table in a routing update message at regular intervals to each neighbour router.
Addressing and Routing
What does routing mean?
Routing is the process of deciding how to move packets from one network to another. The directions also known as routes can be learned by a router using a routing protocol then the information is passed from router to router along the route of the destination.
IP Address's
Every machine connected to the internet is assigned an IP address. An example of an IP address would be 192.168.0.1. IP addresses are displayed in decimal format to make it easier for humans to understand but computers communicate in binary form. The four numbers that separate an IP address are called Octets. Each position consists of eight bits. When added to together you get 32 bit address. The purpose of each octet in an IP address is to create classes of IP addresses that can be assigned within a network. There are three main classes that we deal with Class A, B and C. The octets of an IP address are split into two parts Network and Host. In a class A address the first octet is the network portion, this determines which network the computer belongs to, the last octets of the address are the hosts that belong to the network.
Sub netting
Sub netting allows you to create multiple networks within a class A, B or C address. The subnet address is the address used by your LAN. In a Class C network address you would have a subnet mask of 255.255.255.0. A subnet mask identifies which portion is network and which is host. For example 192.168.6.15 the first octet three octets are the Network address and the last octet being the host(Workstation). It is important to subnet a network because gateways need to forward packets to other LANS. By giving each NIC on the gateway an IP address and a Subnet mask it allows the gateways to route packets from LAN to LAN. Once the packet arrives at its destination, the gateway then uses the bits of the subnet portion of the IP address to decide which LAN to send the packets.
Circuit Switched Leased Lines
A circuit switched network is one that establishes a dedicated circuit (or channel) between nodes and terminals before the users may communicate. Here are some terminologies associated with a Circuit switched network.
Frame relay is a telecommunication service designed for cost-efficient data transmission between local area networks (LANs)
Basic rate interference is a service used by small business for internet connectivity. An ISDN BRI provides two 64 Kbps digital channels to the user. Primary rate interface (PRI) is a telecommunications standard for carrying voice and data transmissions between two locations All data and voice channels are ISDN and operate at 64kbit/s
Packet Switchinghttp://www.raduniversity.com/networks/2004/PacketSwitching/main.htm - _Toc80455261
Packet switching refers to protocols in which messages are broken up into small packets before they are sent. Each packet is then transmitted over the Internet. At the destination the packets are reassembled into the original message. Packet switching main difference from Circuit Switching is that that the communication lines are not dedicated to passing messages from the source to the destination. In Packet Switching, different messages can use the same network resources within the same time period.
http://en.wikipedia.org/wiki/Asynchronous_Transfer_ModeAsynchronous Transfer Mode (ATM) is a cell relay, packet switching network and protocolwhich encodes data into small fixed-sized cells.
ISDN is used to carry voice, data, video and images across a telephone network. ISDN stands for integrated services Digital Network. Isdn also provides users with a 128kbps bandwidth. This is done through frame relay. Frame relay complements and provides a service between ISDN, which offers bandwidth at 128 Kbps and Asynchronous Transfer Mode which operates in somewhat similar fashion to frame relay but at speeds from 155.520 Mbps or 622.080 Mbps. Frame relay is based on the older X.25 packet switching technology and is used to transmit analogue signals such as telephone conversations.
PSDN stands for packet switched data network and is a data communication network. Packet switched networks do not establish a physical communication signal like the public telephone does (circuit switched network) Packets are sent on a fixed length basis and assigned with a source and a destination address. The packets then rely on the routers to read the address and route the packets through the network.
Mobile and Broadband Services
Digital Subscriber line(DSL) is mainly used to bring high bandwidth connections to homes and small business's over a copper wire telephone line. This is can only be achieved if you stay within the range of the telephone exchange. DSL offers download rates of up to 6mbps allowing continuous transmission of video, audio and 3D effects. DSL is set to replace ISDN and compete with the cable modem in providing multimedia to homes. DSL works by connecting your telephone line to the telephone office over copper wires that are twisted together.
Asymmetric Digital Subscribers Line is most commonly used for home users. It provides a high download speed but a lower upload speed. Using ADSL, up to 6.1 megabits per second of data can be sent downstream and up to 640 Kbps upstream.
http://en.wikipedia.org/wiki/Symmetric_Digital_Subscriber_LineSymmetric Digital Subscriber Line is a digital subcriber line which runs over one pair of copper wires. The main difference between ADSL and SDSL is the difference in upload and download speeds. SDSL allows the same upstream data rate and downstream data rate as ADSL upstream can be very slow.
http://searchnetworking.techtarget.com/sDefinition/0,,sid7_gci558545,00.htmlHDSL High bit-rate Digital Subscriber Line, one of the earliest forms of DSL, is used for wideband digital transmission within a corporate site and between the telephone company and a customer. The main characteristic of HDSL is that provides equal bandwidth in both directions.
IDSL is a system in which data is transmitted at 128 Kbps on a regular copper telephone line from a user to a destination using digital transmission.
The Local Loop enables operators to connect directly to the consumer via copper local loops and then add their own equipment to offer broadband and other services. This process involves operators accessing local exchange buildings to connect to a network of copper lines which connect them to homes and businesses. BT is an Example of a Local Exchange. The local loop connecting the telephone exchange to most subscribers is capable of carrying frequencies well beyond the 3.4 kHz upper limit.
Benefits of using DSL
DSL can provide virtually instantaneous transmission of voice, data and video over ordinary copper phone lines. A DSL connection can eliminate delays when waiting to download information and graphics from the Internet. It provides users with a cost effective high speed Internet connection. Another benefit is that a DSL connection is always on-line (like a LAN connection) with no waiting time for dialling or connecting.
There are now more than 10 million broadband connections in the UK. By December 2005 there were 9.792 million broadband connections in the UK and the average broadband take up rate during the three months to December was more than 70,000 per week.
What is a WAN?
There are two prevailing definitions of a Wide Area Network (WAN). The book definition of a WAN is a network that spans large geographical locations, usually to interconnect multiple Local Area Networks (LANs). The practical definition of a WAN is a network that traverses a public network or commercial carrier, using one of several WAN technologies
What are its Main Components?
The main components for a WAN are routers, switches and modems. These components are described below in the hardware section.
CPE - Devices on the subscriber premises are called customer premises equipment (CPE). The subscriber owns the CPE or leases the CPE from the service provider. A copper or fiber cable connects the CPE to the service provider's nearest exchange or central office. This cabling is often called the local loop, or "last-mile".
DTE/DCE - Devices that put data on the local loop are called data circuit-terminating equipment, or data communications equipment (DCE). The customer devices that pass the data to the DCE are called data terminal equipment (DTE). The DCE primarily provides an interface for the DTE into the communication link on the WAN cloud.
HardwareIn a WAN you will need various types of hardware components for it to function. The typical items of hardware that you will need in a WAN are:
Router - An electronic device that connects a local area network (LAN) to a wide area network (WAN) and handles the task of routing messages between the two networks. Operates at layer 3, and makes decisions using IP addresses.
Switch - A switch is a network device that selects a path or circuit for sending a unit of data to its next destination. Operates at layer 2, and uses MAC addresses to send data to correct destination.
Modem - Short for modulator/demodulator, a modem enables a computer to communicate with other computers over telephone lines. Operates at layer 1, where signals are converted from digital to analogue and vice versa for transmission and receiving.
Wan Standards
WANs operate within the OSI model using layer 1 and layer 2 levels. The data link layer and the physical layer. The physical layer protocols describe how to provide electrical, mechanical and functional connections to the services provided by the ISP. The data link layer defines how data is encapsulated for transmission to remote sites.
Encapsulation
Encapsulation is the wrapping of data in a particular protocol header. Remember that WANs operate at the physical layer and the data link layer of the osi model and that higher layer protocols such as IP are encapsulated when sent across the WAN link. Serial interfaces support a wide range of WAN encapsulation types, which must be manually specified. These types include SDLC, PPP, Frame delay etc. Regardless of WAN encapsulation used it must be identical on both sides of the point to point link.
Packet and Circuit Switching
Circuit switching and packet switching are both used in high-capacity networks. The majority of switched networks today get data across the network through packet switching.
Circuit-switching is more reliable than packet-switching. Circuit switching is old and expensive, packet switching is more modern.
General Routing Issues
What is a Routing Protocol?
A routing protocol is a protocol that specifies how routers communicate and exchange information on a network. Each router has prior knowledge of its immediate neighbours and knows the structure of the network topology. The routers know this because the routing protocol shares this information.
Protocol
RIP (Routing Information Protocol) was one of the most commonly uses protocols on internal networks. Routers use RIP to dynamically adapt changes to the network connections and communicate information about which networks routers can reach and the distance between them. RIP is sometimes said to stand for Rest in Pieces in reference to the reputation that RIP has for breaking unexpectedly and rendering a network unable to function.
Routing Algorithms
Distance Vector
This type of routing protocol requires that each router simply inform its neighbours of its routing table. The distance vector protocol is also known as the bellman-ford algorithm.
Link State
This type of routing protocol requires that each router maintain a partial map of the network. The link state algorithm is also know as Dijkstra's algorithm.
IGRP
IGRP is a type of distance vector routing protocol invented by cisco used to exchange routing data in a autonomous system. Distance vector protocols measure distances and compare routes. Routers that use distance vector must send all or a portion of their routing table in a routing update message at regular intervals to each neighbour router.
Addressing and Routing
What does routing mean?
Routing is the process of deciding how to move packets from one network to another. The directions also known as routes can be learned by a router using a routing protocol then the information is passed from router to router along the route of the destination.
IP Address's
Every machine connected to the internet is assigned an IP address. An example of an IP address would be 192.168.0.1. IP addresses are displayed in decimal format to make it easier for humans to understand but computers communicate in binary form. The four numbers that separate an IP address are called Octets. Each position consists of eight bits. When added to together you get 32 bit address. The purpose of each octet in an IP address is to create classes of IP addresses that can be assigned within a network. There are three main classes that we deal with Class A, B and C. The octets of an IP address are split into two parts Network and Host. In a class A address the first octet is the network portion, this determines which network the computer belongs to, the last octets of the address are the hosts that belong to the network.
Sub netting
Sub netting allows you to create multiple networks within a class A, B or C address. The subnet address is the address used by your LAN. In a Class C network address you would have a subnet mask of 255.255.255.0. A subnet mask identifies which portion is network and which is host. For example 192.168.6.15 the first octet three octets are the Network address and the last octet being the host(Workstation). It is important to subnet a network because gateways need to forward packets to other LANS. By giving each NIC on the gateway an IP address and a Subnet mask it allows the gateways to route packets from LAN to LAN. Once the packet arrives at its destination, the gateway then uses the bits of the subnet portion of the IP address to decide which LAN to send the packets.
Circuit Switched Leased Lines
A circuit switched network is one that establishes a dedicated circuit (or channel) between nodes and terminals before the users may communicate. Here are some terminologies associated with a Circuit switched network.
Frame relay is a telecommunication service designed for cost-efficient data transmission between local area networks (LANs)
Basic rate interference is a service used by small business for internet connectivity. An ISDN BRI provides two 64 Kbps digital channels to the user. Primary rate interface (PRI) is a telecommunications standard for carrying voice and data transmissions between two locations All data and voice channels are ISDN and operate at 64kbit/s
Packet Switchinghttp://www.raduniversity.com/networks/2004/PacketSwitching/main.htm - _Toc80455261
Packet switching refers to protocols in which messages are broken up into small packets before they are sent. Each packet is then transmitted over the Internet. At the destination the packets are reassembled into the original message. Packet switching main difference from Circuit Switching is that that the communication lines are not dedicated to passing messages from the source to the destination. In Packet Switching, different messages can use the same network resources within the same time period.
http://en.wikipedia.org/wiki/Asynchronous_Transfer_ModeAsynchronous Transfer Mode (ATM) is a cell relay, packet switching network and protocolwhich encodes data into small fixed-sized cells.
ISDN is used to carry voice, data, video and images across a telephone network. ISDN stands for integrated services Digital Network. Isdn also provides users with a 128kbps bandwidth. This is done through frame relay. Frame relay complements and provides a service between ISDN, which offers bandwidth at 128 Kbps and Asynchronous Transfer Mode which operates in somewhat similar fashion to frame relay but at speeds from 155.520 Mbps or 622.080 Mbps. Frame relay is based on the older X.25 packet switching technology and is used to transmit analogue signals such as telephone conversations.
PSDN stands for packet switched data network and is a data communication network. Packet switched networks do not establish a physical communication signal like the public telephone does (circuit switched network) Packets are sent on a fixed length basis and assigned with a source and a destination address. The packets then rely on the routers to read the address and route the packets through the network.
Mobile and Broadband Services
Digital Subscriber line(DSL) is mainly used to bring high bandwidth connections to homes and small business's over a copper wire telephone line. This is can only be achieved if you stay within the range of the telephone exchange. DSL offers download rates of up to 6mbps allowing continuous transmission of video, audio and 3D effects. DSL is set to replace ISDN and compete with the cable modem in providing multimedia to homes. DSL works by connecting your telephone line to the telephone office over copper wires that are twisted together.
Asymmetric Digital Subscribers Line is most commonly used for home users. It provides a high download speed but a lower upload speed. Using ADSL, up to 6.1 megabits per second of data can be sent downstream and up to 640 Kbps upstream.
http://en.wikipedia.org/wiki/Symmetric_Digital_Subscriber_LineSymmetric Digital Subscriber Line is a digital subcriber line which runs over one pair of copper wires. The main difference between ADSL and SDSL is the difference in upload and download speeds. SDSL allows the same upstream data rate and downstream data rate as ADSL upstream can be very slow.
http://searchnetworking.techtarget.com/sDefinition/0,,sid7_gci558545,00.htmlHDSL High bit-rate Digital Subscriber Line, one of the earliest forms of DSL, is used for wideband digital transmission within a corporate site and between the telephone company and a customer. The main characteristic of HDSL is that provides equal bandwidth in both directions.
IDSL is a system in which data is transmitted at 128 Kbps on a regular copper telephone line from a user to a destination using digital transmission.
The Local Loop enables operators to connect directly to the consumer via copper local loops and then add their own equipment to offer broadband and other services. This process involves operators accessing local exchange buildings to connect to a network of copper lines which connect them to homes and businesses. BT is an Example of a Local Exchange. The local loop connecting the telephone exchange to most subscribers is capable of carrying frequencies well beyond the 3.4 kHz upper limit.
Benefits of using DSL
DSL can provide virtually instantaneous transmission of voice, data and video over ordinary copper phone lines. A DSL connection can eliminate delays when waiting to download information and graphics from the Internet. It provides users with a cost effective high speed Internet connection. Another benefit is that a DSL connection is always on-line (like a LAN connection) with no waiting time for dialling or connecting.
There are now more than 10 million broadband connections in the UK. By December 2005 there were 9.792 million broadband connections in the UK and the average broadband take up rate during the three months to December was more than 70,000 per week.
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