Network technology and data communications

Computer Networks: Network Technology and Data Communications

Now that computing has become an integral part of life and business data communication (sending and receiving data) over long distances is a necessity. There have been number of technological advancements that have enabled networks and their users to communicate with each other, and exchange data easily even if they are in different ends of the world. In this day in age where you are in the world is no longer an issue in regard to communication. Because of this, communication through WANs has been become vital. Wide area networks make it possible for companies to have a single network, which will connect their several offices and departments together. Companies, banks, and large organizations often have their offices spread over a large distance. Without wide area networking the people of a multinational organization can face difficulties communicating with one another . A wide area network is a network where a large number of resources can be deployed in a very wide geographical area. The best example of a WAN is the internet itself by which is the largest network in the world. In order for communication to take place between computers a medium must be used. Examples of this are cables, Routers, Repeaters, Ethernet, hubs and switches.

These different mediums make data communication possible. There are two basic types of Wide Area Network distributed and centralized.

Centralized WANS:

A WAN that consists of a server or a group of servers in a central location to which client computers connect. The server provides most of the functionality of a network. Many banks, high street chains colleges and universities use this kind of WAN.

Distributed WAN:

A wide area network that consists of client and server computers that are distributed throughout the network. This kind of WAN is commonly use for corporate business that have branch offices throughout the world. WANs are important in connecting institutes that are very far from each other. The main purpose of the wan is to establish a secure, fast and reliable communicate channel among the people who are widely away from each other. Wide area networks are often privately owned networks. An example of this WAN is "SURFnet", which is a research network that connects the universities and research centres of the Netherlands with each other.

Adaptive routing or dynamic routing is the method by which a system is capable of alter the path a route as a result of change in conditions this is to allow a high percentage of routes that can have their destination reached this is commonly used in data networking to describe the capability of a network to 'route around' damage, such as loss of a node or a connection between nodes, so long as other path choices are available. Non-adaptive routing or Static routing is a data communication concept describing one way of configuring path selection of routers in computer networks. It is the type of routing characterised by the absence of communication between routers regarding the current topology of the network. This is achieved by manually adding routes to the routing table. Congestion control concerns controlling traffic entry into a telecommunications network, so as to avoid congestive collapse by attempting to avoid over-subscription of any of the processing or link capabilities of the intermediate nodes and networks and taking resource reducing steps, such as reducing the rate of sending packets. It should not be confused with flow control, which prevents the sender from overwhelming the receiver.

Each TCP/IP host is identified by a logical IP address. This address is unique for each host that communicates by using TCP/IP. Each 32-bit IP address identifies a location of a host system on the network in the same way that a street address identifies a house on a city street. Just as a street address has a standard two-part format (a street name and a house number), each IP address is separated into two parts--a network ID and a host The network ID, also known as a network address, identifies a single network segment within a larger TCP/IP internetwork (a network of networks). All the systems that attach and share access to the same network have a common network ID within their full IP address. This ID is also used to uniquely identify each network within the larger internetwork. A 32-bit IP address is segmented into four 8-bit octets. The octets are converted to decimal separated by fullstops.

IP is the post office of the TCP/IP, where IP data sorting and delivery take place. Each in or outgoing packet is called an IP datagram. An IP datagram contains two IP addresses: the source address of the sending host and the destination address of the receiving host. Unlike hardware addresses, the IP addresses within a datagram remain the same as it travels across a TCP/IP network. Routing is the primary function of IP. IP datagrams are exchanged and processed on each host by using IP at the Internet layer. Above the IP layer, is the transport layer the source host pass data in the form of TCP segments or UDP messages to the IP layer. The IP layer assembles IP datagrams with source and destination address information that is used to route the data through the network. The IP layer then passes datagrams down to the network interface layer. At this layer, data-link converts the IP datagrams into frames for transmission over network-specific media on a physical network. This process happens in reverse order on the destination host.

In telecommunications, a circuit switching network is one that establishes a channel between nodes and terminals before the users can communicate successfully, as if the nodes were physically connected with a circuit. A bit delay is constant during a connection, as opposed to packet switching, where packet queues may cause differing packet transfer delays. Each circuit cannot be used by other callers until the circuit is released and a new connection is set up. Even if no communication is taking place in that channel and that it remains unavailable to other users. Channels that are available to be set up are said to be idle. Virtual circuit switching is a packet switching method that may simulate circuit switching so that the connection is established before any packets are transferred then the packets can be delivered in that order. Packet switching is a digital network communications method that groups all transmitted data, into packets. The network that transmits the packets is a shared network which routes each packet then independently allocates transmission resources as needed. The principal goals of packet switching is to optimize the use of any available link capacity, minimize response times and increase the usability of the communication. When traversing network adapters, switches and other network devices packets are buffered and queued, resulting in variable delay depending on the traffic load in the network.

Asynchronous transfer mode (ATM) is an electronic digital data transmission technology. ATM is implemented as a network protocol and was first developed in the mid 1980s. The aim was to design and implementation of a networking strategy that could transport real-time multimedia with priority on audio-visual technology. Two groups, the "International Telecommunications Union" and the "ATM Forum" were involved in the creation of the standards. ATM has been very successful in a WAN scenario and many telecommunication providers have created and used ATM in their wide-area networks. Many ADSL implementations also use ATM. However, ATM has failed to gain wide use as a LAN technology, and lack of development has held back its full potential as an integrated network technology. Since there will always be both brand-new and outdated link-layer technologies not all of them will fit neatly into the synchronous optical networking model.

DSL or xDSL are technologies that provide digital data transmission over wires of a local telephone network. DSL originally stood for digital subscriber loop, but as of as of now the term digital subscriber line has been widely adopted. Asymmetric Digital Subscriber Line (ADSL) is the most popular version of consumer DSL. DSL can be used at the same time and on the same line with a regular telephone, as it uses higher frequency bands that regular telephone so the signals wont confuse one another.

The download speed of DSL is the 384 kilobits per second (kbps) to 20 megabits per second (Mbps) range dependant on the DSL technology, line conditions and service. Typically, upload speed is lower than download speed for ADSL and equal to Symmetric Digital Subscriber Line (SDSL).

General packet radio service (GPRS) is a packet oriented mobile data service available to users of the second generation (2G) of the mobile communication system or the global system for mobile communications (GSM), as well as in the third generation (3G) systems. In the 2G system, GPRS provides data rates of 56-114 kbit/s.

GPRS data transfer is charged per megabyte while data communication using traditional circuit switching is billed per minute irregardless of whether the user is using the capacity or not. GPRS is a best-effort packet switched service, as opposed to circuit switching, where a certain quality of service (QoS) is guaranteed. 2G mobile systems combined with GPRS are described as 2.5G, that is, a technology between the second (2G) and third (3G) generations. It provides moderate speed for data transfer, by using unused time division multiple access (TDMA) an example of this is the GSM system. GPRS is integrated into "GSM Release 97" and newer releases. It was originally standardized by "European Telecommunications Standards Institute" (ETSI), but now by the "3rd Generation Partnership Project" (3GPP).

UMTS (Universal Mobile Telecommunications Service) is a third-generation packet-based transmission of multimedia at data rates of up to 2 megabits per second UMTS offers a set of services to mobile consumer electronics no matter there geographic location. UMTS is based on the "Global System for Mobile" communication standard. It is also endorsed by major professional bodies and manufacturers as the planned standard for mobile technology worldwide. Once UMTS is fully available, computer and phone users can be constantly attached to the Internet wherever they are and will have the same set of capabilities as they do at home. Users will also have access to terrestrial wireless and multimedia networks.

ITU-T H.32x is a series of protocols that address multimedia communications over "Integrated Services Digital Networks (ISDN), Public Switched Telephone Network (PSTN) or Signalling System 7 (SS7)", and 3G mobile networks. H.323 Call Signalling is suited for transmitting calls across networks using a mixture of IP, PSTN, ISDN, and QSIG over ISDN. A call model, similar to the ISDN call model, eases the introduction of IP telephony into existing networks of ISDN-based PBX systems, including transitions to IP-based Private Branch exchanges (PBXs).

Within H.323, an IP-based PBX might be an H.323 Gatekeeper or other call control element that gives service to telephones or videophones. These devices uses both basic services and supplementary services, such as call transfer, park, pick-up, and hold. H.323's strength lies in multimedia communication functionality designed specifically for IP networks.

Bluetooth uses "frequency-hopping spread spectrum", which splits up the data and transmits pieces of up to 79 frequencies. In its basic mode, the modulation is "Gaussian frequency-shift keying" (GFSK). It can achieve an average data rate of 1 Mb/s. Bluetooth provides a way to connect and transmit information between devices such as mobile phones, telephones, laptops, personal computers, printers, Global Positioning System (GPS) receivers, digital cameras, and video game consoles through a secure 2.4 GHz short-range radio frequency bandwidth. The Bluetooth specifications are developed and licensed by the "Bluetooth Special Interest Group" (SIG). The Bluetooth SIG consists of companies in the areas of telecommunication, computing, networking, and consumer electronics.

My recommendation is that the principal of the college waits until (UMTS) is fully available as it will be easier to connect whilst on the move with mobile phones and portable laptops.

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