When computers were first invented, they were designed as stand-alone systems. As computers became more widespread, practical, useful, and indispensable, network systems were developed that allowed communication between computers.
The term "network" describes computers that are connected for the purpose of sharing data, software, and hardware.
The two types of networks include local area networks (LANs) and wide area networks (WANs).
What is LAN.
As the name suggests, LANs cover a limited geographic area, usually a square mile or less. This limited area can be confined to a room, a building, or a group of buildings. Although a LAN can include one central computer connected to terminals, more commonly it connects a group of personal computers.
What is WAN
A WAN covers a much larger geographic area by means of telephone cables and/or other communications channels. WANs are often used to connect a company's branch offices in different cities.
Internet work
is the term used to describe two or more networks that are joined together. The term "Internet" describes the collection of connected networks. The Internet has been made accessible by use of the World Wide Web. The Web allows users to navigate the millions of sites found on the Internet using software applications called Web browsers. People make use of the Internet in numerous ways for both personal and business applications. For instance, an investor is able to access a company directly and set up an investment account; a student is able to research an assigned topic for a class report; a shopper can obtain information on new and used cars.
The Internet concept of global access to information transferred to a private corporate network creates an intranet. In conjunction with corporate Internet access, many companies are finding that it is highly practical to have an internal intranet. Because of the increased need for fast and accurate information, an efficient and seamless communications line enabling all members to access a wealth of relevant information instantaneously is vital.
A company intranet in conjunction with the Internet can provide various types of information for internal and/or external use. Uses such as instantaneous transfer of information, reduced printing and reprinting, and elimination of outof-date information can provide great benefits to geographically dispersed groups. Some examples of information that an intranet might include are company and procedures manuals, a company phonebook and e-mail listings, insurance and benefits information, in-house publications, job postings, expense reports, bulletin boards for employee memoranda, training information, inventory lists, price lists, and inventory control information. Putting such applications on an intranet can serve a large group of users at a substantially reduced cost.
Some companies might want to make some company information accessible to preauthorized people outside the company or even to the general public. This can be done by using an extranet. An extranet is a collaborative network that uses Internet technology to link businesses with their suppliers, customers, or other businesses. An extranet can be viewed as part of a company's intranet.
is the term used to describe two or more networks that are joined together. The term "Internet" describes the collection of connected networks. The Internet has been made accessible by use of the World Wide Web. The Web allows users to navigate the millions of sites found on the Internet using software applications called Web browsers. People make use of the Internet in numerous ways for both personal and business applications. For instance, an investor is able to access a company directly and set up an investment account; a student is able to research an assigned topic for a class report; a shopper can obtain information on new and used cars.
The Internet concept of global access to information transferred to a private corporate network creates an intranet. In conjunction with corporate Internet access, many companies are finding that it is highly practical to have an internal intranet. Because of the increased need for fast and accurate information, an efficient and seamless communications line enabling all members to access a wealth of relevant information instantaneously is vital.
A company intranet in conjunction with the Internet can provide various types of information for internal and/or external use. Uses such as instantaneous transfer of information, reduced printing and reprinting, and elimination of outof-date information can provide great benefits to geographically dispersed groups. Some examples of information that an intranet might include are company and procedures manuals, a company phonebook and e-mail listings, insurance and benefits information, in-house publications, job postings, expense reports, bulletin boards for employee memoranda, training information, inventory lists, price lists, and inventory control information. Putting such applications on an intranet can serve a large group of users at a substantially reduced cost.
Some companies might want to make some company information accessible to preauthorized people outside the company or even to the general public. This can be done by using an extranet. An extranet is a collaborative network that uses Internet technology to link businesses with their suppliers, customers, or other businesses. An extranet can be viewed as part of a company's intranet.
Access by customers would allow entering orders into a company's system. For example, a person may order airline tickets, check the plane schedule, and customize the trip to his or her preferences. In addition to time and labor savings, this type of order entry could also decrease errors made by employees when entering manually prepared orders.
Security and privacy can be an issue in using an extranet. One way to provide this security and privacy would be by using the Internet with access via password authorization. Computer dial in and Internet access to many financial institutions is now available. This is an example of limited access to information. While bank employees have access to many facets of institutional information, the bank customers are able to access only information that has to do with their own accounts. In addition to their banking account number, they would have to use their password to gain access to the information.
Transmission Media
The physical devices making up the communications channel are known as the transmission media. These devices include cabling media (such as twisted-pair cable, coaxial cable, and fiber-optic cable) and wireless media (such as microwaves and other radio waves as well as infrared light). Wireless transmission has the advantage of not having to install physical connections at every point. Microwave stations use radio waves to send both voice and digital signals.
Security and privacy can be an issue in using an extranet. One way to provide this security and privacy would be by using the Internet with access via password authorization. Computer dial in and Internet access to many financial institutions is now available. This is an example of limited access to information. While bank employees have access to many facets of institutional information, the bank customers are able to access only information that has to do with their own accounts. In addition to their banking account number, they would have to use their password to gain access to the information.
Transmission Media
The physical devices making up the communications channel are known as the transmission media. These devices include cabling media (such as twisted-pair cable, coaxial cable, and fiber-optic cable) and wireless media (such as microwaves and other radio waves as well as infrared light). Wireless transmission has the advantage of not having to install physical connections at every point. Microwave stations use radio waves to send both voice and digital signals.
The principal drawback to this system is that microwave transmission is limited to line-of-sight applications. Relay antennas are usually placed twenty-five to seventy-five miles apart and can have no interfering buildings or mountains between them. Earth-based microwave transmissions, called terrestrial microwaves, send data from one microwave station to another, similar to the method by which cellular telephone signals are transmitted.
Earth stations receive microwave transmissions and transmit them to orbiting communication satellites, which then relay them over great distances to receiving earth stations. Usually, geosynchronous satellites are placed roughly twenty-two thousand miles above the earth. Being geosynchronous allows the satellites to remain in fixed positions above the earth and to be constantly available to a given group of earth stations.
Many businesses either lease or rent satellite and/or microwave communication services through the telephone company or other satellite communication companies. If a business has only a small amount of information to be transmitted each day, it may prefer to use a small satellite dish antenna instead.
Earth stations receive microwave transmissions and transmit them to orbiting communication satellites, which then relay them over great distances to receiving earth stations. Usually, geosynchronous satellites are placed roughly twenty-two thousand miles above the earth. Being geosynchronous allows the satellites to remain in fixed positions above the earth and to be constantly available to a given group of earth stations.
Many businesses either lease or rent satellite and/or microwave communication services through the telephone company or other satellite communication companies. If a business has only a small amount of information to be transmitted each day, it may prefer to use a small satellite dish antenna instead.
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