Networking Basics

[InnerPeace]

Connecting to the Internet

Requirements for Internet connection

This page will describe the physical and logical requirements for an Internet connection.
The Internet is the largest data network on earth. The Internet consists of many large and small networks that are interconnected. Individual computers are the sources and destinations of information through the Internet. Connection to the Internet can be broken down into the physical connection, the logical connection, and applications.

A physical connection is made by connecting an adapter card, such as a modem or a NIC, from a PC to a network.

The physical connection is used to transfer signals between PCs within the local-area network (LAN) and to remote devices on the Internet.

The logical connection uses standards called protocols. A protocol is a formal de******ion of a set of rules and conventions that govern how devices on a network communicate. Connections to the Internet may use multiple protocols. The Transmission Control Protocol/Internet Protocol (TCP/IP) suite is the primary set of protocols used on the Internet. The TCP/IP suite works together to transmit and receive data, or information.

The last part of the connection are the applications, or software programs, that interpret and display data in an understandable form. Applications work with protocols to send and receive data across the Internet. A Web browser displays HTML as a Web page. Examples of Web browsers include Internet Explorer and Netscape. File Transfer Protocol (FTP) is used to download files and programs from the Internet. Web browsers also use proprietary plug-in applications to display special data types such as movies or flash animations.

[smile]

thank you innerpeace456
and we wann more

[InnerPeace]

PC basics

Computers are important building blocks in a network. Therefore, you must be able to identify the major components of a PC. Many networking devices are special purpose computers, with many of the same components as general purpose PCs.

A computer must work properly before it can be used to access information such as Web-based content. This will require troubleshoot basic hardware and software problems. Therefore, You must be familiar with the following small, discreet PC components:



You should also be familiar with the following PC subsystems:

Transistor – Device that amplifies a signal or opens and closes a circuit.
Integrated circuit – Device made of semiconductor material that contains many transistors and performs a specific task.
Resistor – An electrical component that limits or regulates the flow of electrical current in an electronic circuit.
Capacitor – Electronic component that stores energy in the form of an electrostatic field that consists of two conducting metal plates separated by an insulating material.
Connector – The part of a cable that plugs into a port or interface.
Light emitting diode (LED) – Semiconductor device that emits light when a current passes through it.
Printed circuit board (PCB) – A circuit board which has conducting tracks superimposed, or printed, on one or both sides. It may also contain internal signal layers and power and ground planes. Microprocessors, chips and integrated circuits and other electronic components are mounted on the PCB.
CD-ROM drive – A device that can read information from a CD-ROM.
Central processing unit (CPU) – The part of a computer that controls the operation of all the other parts. It gets instructions from memory and decodes them. It performs math and logic operations, and translates and executes instructions.
Floppy disk drive – A computer drive that reads and writes data to a 3.5-inch, circular piece of metal-coated plastic disk. A standard floppy disk can store approximately 1 MB of information.
Hard disk drive – A computer storage device that uses a set of rotating, magnetically coated disks called platters to store data or programs. Hard drives come in different storage capacity sizes.
Microprocessor– A microprocessor is a processor which consists of a purpose-designed silicon chip and is physically very small. The microprocessor utilizes Very Large-Scale Integration (VLSI) circuit technology to integrate computer memory, logic, and control on a single chip. A microprocessor contains a CPU.
Motherboard – The main printed circuit board in a computer. The motherboard contains the bus, the microprocessor, and integrated circuits used for controlling any built-in peripherals such as the keyboard, text and graphics display, serial ports and parallel ports, joystick, and mouse interfaces.
Bus– A collection of wires on the motherboard through which data and timing signals are transmitted from one part of a computer to another.
Random-access memory (RAM) – Also known as read-write memory because new data can be written to it and stored data can be read from it. RAM requires electrical power to maintain data storage. If a computer is turned off or loses power all data stored in RAM is lost.
Read-only memory (ROM) – Computer memory on which data has been prerecorded. Once data has been written onto a ROM chip, it cannot be removed and can only be read.
System unit – The main part of a PC, which includes the chassis, microprocessor, main memory, bus, and ports. The system unit does not include the keyboard, monitor, or any external devices connected to the computer.
Expansion slot – A socket on the motherboard where a circuit board can be inserted to add new capabilities to the computer. Figure shows Peripheral Component Interconnect (PCI) and Accelerated Graphics Port (AGP) expansion slots. PCI is a fast connection for boards such as NICs, internal modems, and video cards. The AGP port provides a high bandwidth connection between the graphics device and the system memory. AGP provides a fast connection for 3-D graphics on computer systems.
Power supply– The component that supplies power to a computer.



The following backplane components are also important:

Backplane – A backplane is an electronic circuit board containing circuitry and sockets into which additional electronic devices on other circuit boards or cards can be plugged; in a computer, generally synonymous with or part of the motherboard.
Network interface card (NIC) – An expansion board inserted into a computer so that the computer can be connected to a network.
Video card– A board that plugs into a PC to give it display capabilities.
Audio card – An expansion board that enables a computer to manipulate and output sounds.
Parallel port – An interface capable of transferring more than one bit simultaneously that is used to connect external devices such as printers.
Serial port – An interface that can be used for serial communication in which only one bit is transmitted at a time.
Mouse port – A port used to connect a mouse to a PC.
USB port– A Universal Serial Bus connector. A USB port connects devices such as a mouse or printer to the computer quickly and easily.
Firewire– A serial bus interface standard offering high-speed communications and isochronous real-time data services.
Power cord – A cord used to connect an electrical device to an electrical outlet that provides power to the device.
Think of the internal components of a PC as a network of devices that are all attached to the system bus.

[InnerPeace]

Network Interface Card

This page will explain what a NIC is and how it works. You will also learn how to select the best NIC for a PC.

A NIC, or LAN adapter, provides network communication capabilities to and from a PC. On desktop computer systems, it is a printed circuit board that resides in a slot on the motherboard and provides an interface connection to the network media. On laptop computer systems, it is commonly integrated into the laptop or available on a small, credit card-sized PCMCIA card. PCMCIA stands for Personal Computer Memory Card International Association. PCMCIA cards are also known as PC cards. The type of NIC must match the media and protocol used on the local network.

The NIC uses an interrupt request (IRQ), an input/output (I/O) address, and upper memory space to work with the operating system. An IRQ value is an assigned location where the computer can expect a particular device to interrupt it when the device sends the computer signals about its operation. For example, when a printer has finished printing, it sends an interrupt signal to the computer. The signal momentarily interrupts the computer so that it can decide what processing to do next. Since multiple signals to the computer on the same interrupt line might not be understood by the computer, a unique value must be specified for each device and its path to the computer. Prior to Plug-and Play (PnP) devices, users often had to set IRQ values manually, or be aware of them, when adding a new device to a computer.

These considerations are important in the selection of a NIC:

Protocols – Ethernet, Token Ring, or FDDI
Types of media – Twisted-pair, coaxial, wireless, or fiber-optic
Type of system bus – PCI or ISA

[InnerPeace]

NIC and modem istallation

This page will explain how an adapter card, which can be a modem or a NIC, provides Internet connectivity. You will also learn how to install a modem or a NIC.

A modem, or modulator-demodulator, is a device that provides the computer with connectivity to a telephone line. A modem converts data from a digital signal to an analog signal that is compatible with a standard phone line. The modem at the receiving end demodulates the signal, which converts it back to digital. Modems may be installed internally

or attached externally to the computer using a phone line.

A NIC must be installed for each device on a network. A NIC provides a network interface for each host. Different types of NICs are used for various device configurations. Notebook computers may have a built-in interface or use a PCMCIA card. Figure

shows PCMCIA wired, wireless network cards, and a Universal Serial Bus (USB) Ethernet adapter. Desktop systems may use an internal network adapter , called a NIC, or an external network adapter that connects to the network through a USB port.

Situations that require NIC installation include the following:

Installation of a NIC on a PC that does not already have one
Replacement of a malfunctioning or damaged NIC
Upgrade from a 10-Mbps NIC to a 10/100/1000-Mbps NIC
Change to a different type of NIC, such as wireless
Installation of a secondary, or backup, NIC for network security reasons
To perform the installation of a NIC or modem the following resources may be required:

Knowledge of how the adapter, jumpers, and plug-and-play software are configured
Availability of diagnostic tools
Ability to resolve hardware resource conflicts

[InnerPeace]

Overview of High-speed and dial-up connectivity

This page will explain how modem connectivity has evolved into high-speed services.

In the early 1960s, modems were introduced to connect dumb terminals to a central computer. Many companies used to rent computer time since it was too expensive to own an on-site system. The connection rate was very slow. It was 300 bits per second (bps), which is about 30 characters per second.

As PCs became more affordable in the 1970s, bulletin board systems (BBSs) appeared. These BBSs allowed users to connect and post or read messages on a discussion board. The 300-bps speed was acceptable since it was faster than the speed at which most people could read or type. In the early 1980s, use of bulletin boards increased exponentially and the 300 bps speed quickly became too slow for the transfer of large files and graphics. In the 1990s, modems could operate at 9600 bps. By 1998, they reached the current standard of 56,000 bps, or 56 kbps.

Soon the high-speed services used in the corporate environment such as Digital Subscriber Line (DSL) and cable modem access moved to the consumer market. These services no longer required expensive equipment or a second phone line. These are "always on" services that provide instant access and do not require a connection to be established for each session. This provides more reliability and flexibility and has simplified Internet connection sharing in small office and home networks.

[InnerPeace]

TCP/IP de******ion and configuration

This page will introduce the Transmission Control Protocol/Internet Protocol (TCP/IP).

TCP/IP is a set of protocols or rules that have been developed to allow computers to share resources across a network. The operating system tools must be used to configure TCP/IP on a workstation. The process is very similar for Windows or Mac operating systems.

[InnerPeace]

Testing connectivity with ping

This page will explain how the ping command is used to test network connectivity.

Ping is a basic program that verifies a particular IP address exists and can accept requests. The computer acronym ping stands for Packet Internet or Inter-Network Groper. The name was contrived to match the submariners' term for the sound of a returned sonar pulse from an underwater object.

The ping command works by sending special Internet Protocol (IP) packets, called Internet Control Message Protocol (ICMP) Echo Request datagrams, to a specified destination. Each packet sent is a request for a reply. The output response for a ping contains the success ratio and round-trip time to the destination. From this information, it is possible to determine if there is connectivity to a destination. The ping command is used to test the NIC transmit and receive function, the TCP/IP configuration, and network connectivity. The following types of ping commands can be issued:

ping 127.0.0.1 – This is a unique ping and is called an internal loopback test. It is used to verify the TCP/IP network configuration.
ping IP address of host computer – A ping to a host PC verifies the TCP/IP address configuration for the local host and connectivity to the host.
ping default-gateway IP address – A ping to the default gateway indicates if the router that connects the local network to other networks can be reached.
ping remote destination IP address – A ping to a remote destination verifies connectivity to a remote host.

[InnerPeace]

Web browser and plug-ins

This page will explain what a Web browser is and how it performs the following functions:

Contacts a Web server
Requests information
Receives information
Displays the results on the screen

A Web browser is software that interprets HTML, which is one of the languages used to code Web page content. Some new technologies use other markup languages with more advanced features. HTML, which is the most common markup language, can display graphics or play sound, movies, and other multimedia files. Hyperlinks that are embedded in a Web page provide a quick link to another location on the same page or a different Internet address.

Two of the most popular Web browsers are Internet Explorer (IE) and Netscape Communicator. These browsers perform the same tasks. However, there are differences between them. Some websites may not support the use of one of these browsers. It is a good idea to have both programs installed.

Here are some features of Netscape Navigator:

Was the first popular browser
Uses less disk space
Displays HTML files
Performs e-mail and file transfers

Here are some features of IE:

Is powerfully integrated with other Microsoft products
Uses more disk space
Displays HTML files
Performs e-mail and file transfers

There are also many special, or proprietary, file types that standard Web browsers are not able to display. To view these files the browser must be configured to use the plug-in applications. These applications work with the browser to launch the programs required to view special files:

Flash – Plays multimedia files created by Macromedia Flash
Quicktime – Plays video files created by Apple
Real Player – Plays audio files

Use the following procedure to install the Flash plug-in:

1- Go to the Macromedia website.
2- Download the latest flash player installer file.
3- Run and install the plug-in in Netscape or IE.
4- Access the Cisco Academy website to verify the installation and proper operation.

Computers also perform many other useful tasks. Many employees use a set of applications in the form of an office suite such as Microsoft Office. Office applications typically include the following:

- Spreadsheet software contains tables that consist of columns and rows and it is often used with formulas to process and analyze data.
- Modern word processors allow users to create documents that include graphics and richly formatted text.
- Database management software is used to store, maintain, organize, sort, and filter records. A record is a collection of information identified by some common theme such as customer name.
- Presentation software is used to design and develop presentations to deliver at meetings, classes, or sales presentations.
- A personal information manager includes an e-mail utility, contact lists, a calendar, and a to-do list.


Office applications are now a part of daily work, as typewriters were before PCs.

[InnerPeace]

Network Math

Binary presentation of data

This page will explain how computers use the binary number system to represent data.

Computers work with and store data using electronic switches that are either ON or OFF. Computers can only understand and use data that is in this two-state or binary format. The 1s and 0s are used to represent the two possible states of an electronic component in a computer. 1 is represented by an ON state, and 0 is represented by an OFF state. They are referred to as binary digits or bits.

American Standard Code for Information Interchange (ASCII) is the code that is most commonly used to represent alpha-numeric data in a computer. ASCII uses binary digits to represent the symbols typed on the keyboard. When computers send ON or OFF states over a network, electrical, light, or radio waves are used to represent the 1s and 0s. Notice that each character is represented by a unique pattern of eight binary digits.

Because computers are designed to work with ON/OFF switches, binary digits and binary numbers are natural to them. Humans use the decimal number system, which is relatively simple when compared to the long series of 1s and 0s used by computers. So the computer binary numbers need to be converted to decimal numbers.

Sometimes binary numbers are converted to hexadecimal numbers. This reduces a long string of binary digits to a few hexadecimal characters. It is easier to remember and to work with hexadecimal numbers.

[InnerPeace]

Bits and bytes

This page will explain what bits and bytes are.

A binary 0 might be represented by 0 volts of electricity.

A binary 1 might be represented by +5 volts of electricity.

Computers are designed to use groupings of eight bits. This grouping of eight bits is referred to as a byte. In a computer, one byte represents a single addressable storage location. These storage locations represent a value or single character of data, such as an ASCII code. The total number of combinations of the eight switches being turned on and off is 256. The value range of a byte is from 0 to 255. So a byte is an important concept to understand when working with computers and networks.

[InnerPeace]

Base 10 number system

Numbering systems consist of symbols and rules for their use. This page will discuss the most commonly used number system, which is decimal, or Base 10.

Base 10 uses the ten symbols 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9. These symbols, can be combined to represent all possible numeric values.

The decimal number system is based on powers of 10. Each column position of a value, from right to left, is multiplied by the base number 10 raised to a power, which is the exponent. The power that 10 is raised to depends on its position to the left of the decimal point. When a decimal number is read from right to left, the first or rightmost position represents 100, which equals 1. The second position represents 101, which equals 10. The third position represents 102, which equals 100. The seventh position to the left represents 106, which equals 1,000,000. This is true no matter how many columns the number has.

Here is an example:

2134 =
(2x10^3) + (1x10^2) + (3x10^1) + (4x10^0)

This review of the decimal system will help you understand the Base 2 and Base 16 number systems. These systems use the same methods as the decimal system.

[InnerPeace]

Base 2 number system


This page will discuss the number system that computers use to recognize and process data, which is binary, or Base 2.
The binary system uses only two symbols, which are 0 and 1. The position of each digit from right to left in a binary number represents the base number 2 raised to a power or exponent. These place values are, from right to left, 20, 21, 22, 23, 24, 25, 26, and 27, or 1, 2, 4, 8, 16, 32, 64, and 128 respectively.

Here is an example:

101102 =
(1 x 2^4 = 16) + (0 x 2^3 = 0) + (1 x 2^2 = 4) + (1 x 2^1 = 2) + (0 x 2^0 = 0) = 22 (16 + 0 + 4 + 2 + 0)

This example shows that the binary number 10110 is equal to the decimal number 22.

[InnerPeace]

Converting decimal numbers to 8-bit binary numbers


This page will teach you how to convert decimal numbers to binary numbers.


Conversion exercise:

Use the example below to convert the decimal number 168 to a binary number:

128 is less than 168 so the left most bit in the binary number is a 1. 168 - 128 = 40.
64 is not less than or equal to 40 so the second bit from the left is a 0.
32 is less than 40 so the third bit from the left is a 1. 40 - 32 = 8.
16 is not less than or equal to 8 so the fourth bit from the left is a 0.
8 is equal to 8 so the fifth bit from the left is a 1. 8 - 8 = 0. Therefore, the bits to the right are all 0.

This example shows that the decimal number 168 is equal to the binary number 10101000.

[InnerPeace]

Converting 8-bit binary numbers to decimal numbers

This page will teach you how to convert binary numbers to decimal numbers.

Here is an example:

Convert the binary number 01110000 to a decimal number.


NOTE:
Work from right to left. Remember that anything raised to the 0 power is 1.

0 x 20 = 0

0 x 2^1 = 0

0 x 2^2 = 0

0 x 2^3 = 0

1 x 2^4 = 16

1 x 2^5 = 32

1 x 2^6 = 64

0 x 2^7 = 0

__________

= 112