How do telecommunications networks work

The system for connecting subscribers has progressed from being purely circuit-switched to packet-switched. Telecommunication networks for transmitting data formerly used numerous different protocols. Owing to the triumph of the internet, the internet protocol IP has gained widespread acceptance as standard protocol for data transmission. Nowadays, virtually all data networks are IP-based. The data in these networks are divided up into individual data packets and tagged with the destination and source addresses.

At the network nodes, the destination addresses are evaluated by so-called routers, and the data packets are sent to the next node along the route to the destination address. In principle, the individual packets can find differing routes through the network and reach their destination at different times. There are many different types of telecommunication networks.

Some of the key characteristics of WAN are: WAN can cover a large geographical area and It can be a private or a public network The data is transmitted in digital form. Communication mediums like satellites, public telephone networks are connected by routers. Messages in the form of pictures, sound, videos, or data can be sent easily and quickly to anyone else on the same network.

Setting up a WAN is not a simple task. It is very complicated, time-consuming, and expensive Maintaining a WAN requires constant supervision of network supervisors and technicians. Data security is a real problem as different people use or access information from different computers.

Local Area Networks LANs — Local area networks LANs are telecommunication networks that connect different information processing devices like computers within a limited physical area. It connects computers or communication devices in a restricted geographical area like a school campus or office building. Different resources like printers, modems, servers can be shared by the end-users with the help of local area networks.

This helps reduce cost. It helps save the cost of purchasing licensed software for each user in the network. The same software can be shared and used over LANs Data and information can be easily shared and transferred over the computers or devices on the same network.

The data of all users is saved on the hard disk of the server computer. Such a setup facilitates uninterrupted services and fail-over capabilities during maintenance windows, equipment failure or in case of accidents. The devices used to transport data are known as network transport equipment. Some of the widely used equipment are manufactured by. The capacity of a network is mainly dependent on the type of signaling scheme employed on transmitting and receiving end.

In the earlier days, a single wavelength light beam was used to transmit data, which limited the bandwidth to the maximum operating frequency of the transmitting and receiving end equipment. Each node in the network is able to access different channels, but is mostly tuned to a few channels. This eliminates the need to convert all the channels to electric signals, extract the required channels, and convert the rest back to optical into the OTN.

The extracted channels at a site are connected to local devices through muxponder or tranponder cards that can split or combine 40G channels to 4x 10G channels or 8x 2. Click for a larger view of the image. Skip to main content. Module 7: Networks and Security. Search for:. Reading: Telecommunications Network Example of how nodes may be interconnected with links to form a telecommunications network. A LAN gives its users the following capabilities:. Users can share resources, such as a fast printer or a database.

Users can collaborate by communicating over their LAN. This collaboration may be facilitated by groupware that runs on a LAN. Users can access other networks within a firm or outside of it via bridges and routers. There are two principal LAN designs :. Peer-to-peer - peripherals are located at terminals and system administration is largely left up to the users. Server-based networks - shared resources are placed a dedicated server that manage a given resource on behalf of user workstations sharing the resource file server, printer server, gateway, optical disk server.

Most of the servers are dedicated to their task; using them as workstations degrades the performance of the net. A company with a large number of telephones from 50 to over 10, often elects to own a computer-based private branch exchange PBX , an electronic switchboard that interconnects its telephones and provides connections to the public network. Characteristics of a PBX:. Gives a company control over the usage of its telephone system and offers a variety of features, such as call forwarding or voice messaging.

Maybe employed as a switch for data communications. Many newer PBXs use digital technology, eliminating the need for modems, and perform conversions needed to ensure connectivity between various equipment and telecommunications links.

Easy to connect a new workstation to the net. Speeds of PBX-based networks are limited. An important current development in organizational computing is downsizing - moving from platforms based on mainframes and minicomputers to a microcomputing environment.

The processing of a given application is split up among a number of clients - serving individual users - and one or more servers - providing access to databases and doing most of the computing. Main objective of a client is to provide a graphical user interface to a user. Main objective of a server is to provide shared services to clients. Two-Tier Architecture. Three-Tier Architecture. Characteristics of Two-Tier Architecture: [Figure 7.

Client performs presentation services. It displays the GUI and runs the program that determines what happens when the user selects a menu option. Server manages the accesses to the database. Clients send remote procedure calls to activate specific applications logic on a server. Characteristics of Three-Tier Architecture: [Figure 7. An application server runs most of the application logic, with the user workstation responsible for the display at the front end and the database server providing database servers at the back end.

Objective is to distribute application so as to reduce the overall hardware costs while minimizing the network traffic. Is attractive in terms of their acquisition price as related to their performance. Is moving computing control out of the data centers and into the end-user areas. Software is complex, and is expensive to maintain. Generate significant traffic on the firm's backbone network that connects clients and servers. Wide area networks are the fundamental infrastructure of organizational computing.

These long-distance telecommunications networks employ a variety of equipment so that the expensive links may be used effectively. The offerings of common carriers and of providers of value-added services may be combined with private networks to create an overall organizational network.

WANs include equipment that controls message transfer and makes it possible to share the links among a number of transfers. A WAN has a powerful host computer. The host runs a system program, called a telecommunications monitor, which processes incoming messages, passing them to the appropriate application programs, and accepts outgoing messages from the applications in order to transmit them into the network. Front-End Processor. Relieves the host computer of most of the tasks involved in network control.

Under the control of its own software, the front-end processor accepts messages coming from the network and routes outgoing messages to their destinations. It performs the necessary code conversions, encrypts and decrypts secure messages, and performs error checking so that the host deals with Aclean messages.

Cluster Controller. Manages several terminals, connecting them to a single telecommunications link, and performs communication tasks for them, such as screen formatting, code conversion, and error checking. A cluster controller may also allow the terminals to share a high-speed printer and may handle electronic mail among the cluster terminals.

Combines the data that terminals send to it over local low-speed links into a single stream. This stream is then transmitted over a high-speed telecommunications channel and is split by another multiplexor on the opposite end of the channel.

Combines transmission from several slower terminals that operate in a burst mode into a single transmission stream that requires a link of lower speed than the sum of the speeds of all the terminals combined. A concentrator stores messages from terminals and forwards them when warranted. Establishes connections between nodes that need to communicate. Include a variety of dumb terminals, with no processing capacity and intelligent terminals with processing capacity, such as personal computers.

Some network facilities are owned by user organizations, others can be leased by them, or simply used on a pay-as-you-go basis. Among the typical facilities owned by user firms are workstations, host computers, and front-end processors. The essential providers of telecommunications links and services are common carriers and the vendors of enhanced services on value-added networks.

These include:. Providers of value-added networks. Private lines and private networks. Are companies licensed by a country's government to provide telecommunications services to the public. The vast majority of common carriers provide telephone service.

These carriers offer the use of a wide-area telecommunications infrastructure, that is, facilities for the transmission of voice and data messages.

Common carriers offer a service called virtual private network where a user firm can purchase guaranteed access to facilities with specified capabilities, such as transmission speed and access points.

Providers of Value-Added Networks. Value-added vendors lease facilities from the common carriers and provide telecommunications services to their own customers. These vendors add value to the basic infrastructure furnished by the common carrier. The value-added networks VAN provided by the vendors furnish services over and above those provided by common carriers. Private Lines and Private Networks.

Instead of using a service that has to be shared with others, a firm may lease its own private lines or entire networks from carriers. This can have economic advantages as compared with VAN use, as well as provide faster and more secure communications. The Internet has changed the face of individual and organizational computing.

Driven by the possibilities offered by the Internet and the Web, electronic commerce is expanding its reach. Present and Future of the Internet. The Internet is the global network of computer networks without a centralized control that has become the contemporary Ainformation highway.

Characteristics of the Internet:. It is run in a decentralized fashion by a number of voluntary organizations, the principal of which is the Internet Society. It is a medium of communication, a source of information, and a developing means of electronic commerce.

A major obstacle to its development has become the limited capacity of the links interconnecting the networks.