Networking Basics

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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

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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.

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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.

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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.

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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.

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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.

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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.