A Network Technology And Data Communications Information Technology Essay

A Network Technology And data Communications Information Technology EssayA WAN, or Wide Area Network, is a network that covers a large area, for example computers on opposite sides of the planet communicating. Usu completelyy, WANs are 2 or much LANs (Local Area Networks) affiliated together. One of the most well-known examples of a WAN is something we all use every day the Internet.Types of WANsPTO Switched ServicesHere I will look at some of the most commonly known examples of PTO Switched Services.Circuit SwitchingCircuit switching is based on the transmitter and receiver making the most of the full communication channel for the space of the communication. This type of switching can be found in the Public Switched think Network (PSTN) where telephone calls are started by the person dialling but arent completed until the person receiving the call answers.The main advantage of circuit switching is that it is extremely received for what it does. Another advantage is that once the connection is rope up, it is fast to use and relatively error-free.The disadvantages include the cost of the initial set up and the time that it takes to set up the particular channel. There is in any case the chance of a failure at one point ca victimisation a disruption in all communications. Lastly, although there are many paths available, you can only communicate on one path at a time, meaning that if you want to talk to psyche else you will have to start the process again, in the same vein once a path is established that channel will be unavailable to other users.To attempt to overcome the problems of circuit switching, packet switching was introduced.Examples of Circuit SwitchingPSTNPSTN, or Public Switched Telephone Network, is a circuit-switching network that uses internationally concord codes and unique identifiers (telephone represss) to operate.The PSTN network was originally made for fixed-line parallel telephone systems but the PSTN is now almost completely di gital and also incorporates mobile telephones alongside analogue ones.ISDNISDN, or Integrated Services Digital Network, is a communications standard used internationally to send data, including voice and video, over digital or regular phone lines, at the same time.One of the most well known uses of ISDN is for Internet access, with ISDN providing a maximum speed for upload and download of 128 Kbit/s.Leased LinesA leased line is a symmetric telecommunications line connecting two locations for voice and/or data communications. Unlike PSTN lines, leased lines dont have a telephone number instead each side of the line is permanently connected to the other.Usually, leased lines are used by businesses to directly connect offices that are far apart, merely shorter outgos are also used for convenience. The main difference between leased lines and dial-up connections is that a leased line is always active. The main advantage of leased lines is the take on of a high level of quality, this is because the connection doesnt carry anybody elses data.Packet SwitchingPacket switching is a communications method that works by dissever the data being sent into smaller chunks, called packets.When the data is sent it can end up being sent through different paths to arrive at its destination. Each time a packet goes through a switch, router or adapter it is buffered and queued, which can slow down how quick the packets arrive at their destination, which also means the order of delivery can also be different.Examples of Packet SwitchingX.25X.25 is one of the oldest packet-switched services that are still available and used, although it is now being replaced by less complex protocols, like IP (internet Protocol). It was developed onwards the OSI Reference Model so the protocol suite is essentially just three layers, which are almost the same as the lower three layers of the seven-layer OSI model (Physical, Data and Network layers).X.25 is designed to operate effectively regar dless of which systems are connected to the network. It is typically used by telephone service providers which allows them to charge their customers based on their use of the network.Frame RelayFrame relay is a telecommunication service geared towards cost-efficient data transmission between local area networks and wide area networks. Frame relay sends packets at the data attach layer of the OSI model rather than at the Network layer. A frame can use packets from different protocols such as Ethernet and X.25 and is also variable in size with some being as large as 1000bytes or more.Frame Relay was originally a stripped-down version of X.25, but managed to distance itself from the error-correcting which is most commonly associated with X.25. Instead when Frame Relay finds an error, it just drops the packet. Frame Relay works on the basis of shared-access and uses a technique known as best-effort, where error-correction is almost obsolete however there is also no guarantee of reliabl e data delivery, instead it leaves the error correcting to each end of the connection.SMDSSMDS, or Switched Multimegabit Data Service, is a telecommunications service that provides connectionless, high-performance, packet-switched data transport. As SMDS is neither a protocol nor a technology, it means that it can support standard protocols and communications interfaces that are using current, as well as future, technology.SMDS can use either fibre or copper-based lines and works on the data link and physical layers of the OSI model.Mobile and broadband ServicesThe greatest change to WANs and most internet services in the near future is expected to be the rise and increase of quality in mobile and broadband services and standards.ATMATM, or Asynchronous Transfer Mode (ATM) is a data link as well as a network layer circuit switched protocol which is connection based. For example a logical connection has to be made between both end points before data can start to be sent or received. ATM also divides the data being sent into small sized cells, each consisting of 53 bytes (48 Bytes for Data and 5 Bytes for Header Information).The process of splitting the data into a fixed size is what makes ATM different from packet switched networks that use different length packets, like IP.xDSLDSL, or Digital Subscriber Line, provides customers with digital services through their telephone system. The x simply means that there are a project of different DSL technology available.DSL is probably the most used method for people to access digital services, such as the internet as it is cheaper than leased lines and also faster than ISDN, with speeds of upto 1.5Mb/s download speed and 128kb/s upload speed available on ADSL (Asymmetric DSL).This is down to the fact that DSL uses a digital modem rather than an analogue one, meaning that the data doesnt need to be converted before it is sent.