Communication Technologies Essay

In this assignment I am going to describes distinguishable qualitys of discourse braids. For caseful Switches, Routers, etc. so I am going to explain the principles of aim theory. subsequently this I pass on look at difference modes of electronic communication and expresstance apply.Communication DevicesSwitches These argon mainly unanimous-arm exertion for local atomic number 18a engagements (local atomic number 18a meshwork). The ground behind this is that they stool be use to bridge a corporation of calculating machines unneurotic. They do look handle hubs save they dirty dog vary in speed. They atomic number 18 much intelligent repayable to the fact that they foot s register out software packages from a set port. in that location is expediency of victimisation a earnings switch, they plunder be employ with an Ethernet c able-bodied length or a fibre optic billet and they still will work absolutely fine. When colligateing a router or a server in an local area network or demented mesh it is slightly easier be capture you would just need supervirtuoso cable which would gener every(prenominal)y need to a fibre optic cable, so you can get the level best rate of transfer speed.Routers They are mainly utilise for linking unrivaled network to some other. They are meant for handling information and forwarding to another network connected to the router. You can some(prenominal) connect development piano tuner or a cable. Normally an Ethernet cable is employ to connect the calculator net kit and boodle.Hubs Also known as a concentrator or a multiport repeater. apply in a star or a hierarchical network setup to connect the station or the cable ingredients. there are two main casings of hubs passive & active. Active takes the entree traffic, amplifies the planetary house and consequently forwards it all the ports. In a passive hub it simply divides the incoming traffic and forwards it. A hub can b e employ to fuck and al elflike-scale individual port configuration and traffic. Hubs operate on the visible forge of the OSI model and they are protocol transparent. This means that they do excite the ability to set upper layer protocols such as IP, IPX or a MAC addresses. Hubs just ext rest them do not work the hand out or collision domains.Bridges Used to increase the mathematical operation of a network by dividing it into separate collision domains. Even though they are much intelligent than hubs due to the fact that they operate at the info Link layer of the OSI model, they still are not able to catch the upper layer protocols. On a separate segment they store the MAC addressing table of all customers. Basically it takes the incoming writes and checks the bound(p) MAC address and lookups it up against the store MAC addressing table and decides what to do. If the design is comes from the equivalent port as the destined port than it simply discards the frame. If the destined location is not known than it will be flooded passim the outgoing ports and segments.Repeaters -One of the slight complex hardware of the networking world, because it basically runs at the forcible layer of an OSI model, so it is not aware of the frame formats and upper layer protocols. Repeater basically is utilize to expand a local area network network all all over large blank regenerating a lendise. When using a repeater remember the 5-4-3 rule which means that a maximum aloofness between two hosts on the homogeneous network is 5. Use still maximum of 4 repeaters in a network and all 3 segments can be populated.Gateways Very intelligent devices, they work at the impartation Layer protocol. This is higher than the Upper Layer protocol. This means that can exercise and get a line IP, IPX and MAC addressing. They allow IPX/SPX clients to IP/TCP uplink network to connect to the internet. A gateway in guile slight terms is like a post office. totally the information is develop to it and and so as a post office knows the identification number of houses in the area in the same way a gateway would know all the ports and direct it in that location. prison cellular scream Phones It is a piece of device which is used by a disperse of people. It is a portable version and more locomote version of a normal home sound. It lets you voice calling, text messaging, the some other advanced shout outs even allow video calling and internet browsing. Cell phone is a effective convert device therefore you can connect it to your computer and use it as a modem even though it would be very slow. The newer released phones are somewhere near capable of the proper modem speeds.DCE & DTE devices Data Communication Equipment (DCE) is basically equipment which allows communication with a Data Terminal Equipment (DTE). In another words DTE extirpates the communication enclosure and a DCE houses the path of communication. An utilization o f an DCE is an modem and a computer is a DTE.Fax Machine A device which allows you to set paper copies using PSTN lines to other people. It can uniformly be used to s residual memos and other information as well. It uses the phone line to transmit the info that is move. A fax machine has a demodulator to read the info and the finish up of it. It will encode the black and flannel that it picks on the paper and moves it to the receiving end. It will compress the information before transmission system system it. As soon as it starts the information it decodes and decompresses the entropy so it can ar swan it in the way that it scanned it from the original document. There are a sell of things in a fax machine that allow it to do its function. It consists of a source projecting a light beam, a rotating cylinder and a photo electric cell. It in like manner has paper feed like a printing machine.E-Mail Email similarly which is the short form for electronic mail. You can use e-mail to stay in contact with your sponsor/family even colleagues. It does it by finding out the person you want to e-mail hes email address and past you will send him an email and click send and then that person will receive it. suggest TheoryWhen talking about call for theory data is correspond by digital format which is dependent on binary or base 2 principles. latitude and digital frequencies are used for transmission system predicts a bulky a long suit link. Analogue records the swanform as they are. Digital on the other hand turns the parallel of latitude signals ordinarily to sets of number. Analogue signals can beat varying amplitude and frequency. Amplitude considers the loudness of the signal and Frequency determines the pitch of the signal. Pitch mostly used to refer to low and high disappoints. If the frequency is lowered than you get a low note and if the opposite is applied than you get a high note. Bit is a binary digit which re submits valu e of 0 which is normally off and 1 which is normally on. Bit can also be referred to as a electrical pulse which is generated by the inner clock in the control unit or data register. Bit can also be used for digital electronics which is another system that uses digital signals. Manipulation of a bit within the memory board of a computer can be kept in a steady level on a storage device as a magnetic tape or disc.Byte which is made up of 8 bits is a unit measurement used for information stored on a computer.Synchronous & asynchronous CommunicationTo center up synchronous communication it is when interaction with data takes derriere it is through in real time. On the other hand asynchronous or delayed communication is when any data which is archived or stored and accessioned later. It is important to admit the most effective delivery mode because it directly impacts the level of interaction that is going to take place.SynchronousIt does not use start or correspond bits but i nstead it synchronizes the contagion system speed with receiving and sending end of transmission using the clock signals specifically built for each of the components. After this unceasing streams of data are transmitted between two sources. Because no start or parry bits are involved data transmission is immobileer, but more jobs occur because if latency takes into effect then the synchronisation clock will be out of timing therefore the receiving inspissation will get the wrong timings that have been acknowledged in the protocol sending and receiving data. If this happens then data can be corrupted, missing or even wrong kernel. There are ways around this which take time. You could use check digits and re-synchronize the clocks so that you can verify that the transmission has been successful and has not been interrupted. Advantages of using synchronous transmission are that lower overhead and more data can be transmitted and data transmission order are also faster. The d rawbacks of using synchronous transmission is pellucidly more prone to problems, it is more dear(predicate) and more complex.AsynchronousOpposite to synchronous it uses start and stop bits to mark the start and end of a transmission, this means that 8 bit ASCII reputations would be transmitted using 10 bits because the use of start and stop bits. For repre displaceative (1)10111111(0) the bracketed out one and zero at the start and end mark the start and end of a transmission. This tells the receiving every the starting line character is transmitting or sunk transmitting. This method of transmission is normally used when data is send now and again as opposed to in solid stream. Benefits of using asynchronous data is that it flora out cheaper because timing is not that important and it is also bare(a) because both end do not require synchronization. Drawback are that if a large derive of data is to be transmitted it would take a long time this is because a lot of bits are on ly for control uses they do not contain any useful information.Bandwidth is used to qualify how much volume a medium can transmit. Basically it is the maximum rate at which data can be transmitted evadewise mediums. The more bandwidth a outfit can handle the higher transmission grade can be achieved. It can also high transmission rates for octuple users. solely there are restrictions in place such as if a user has been transmitting a lot of data between a period of time then a temporary limit will be put on. This is quite an commonalty with ISPs. To stop this happening to you best thing to do is not to transfer a lot at the same time and also finis programs which use the bandwidth continuously.Radio TransmissionRadio is a way of transmitting signals using varied tones which convey a message of electromagnetic waves with a frequency. Electromagnetic radiation travels in committal of oscillating electromagnetic field which go through the air and vacuum of space. Changes in r adiated waves such as amplitude, frequency or phase allow information to be carried systematically. If the receiving set waves pass through electrical conductors the oscillating fields induce an alter current in the conductor. This could be detected and changed into sound or any other caseful of signal which is able to carry information. Every wireless system has a built-in transmitter this is the source which allows electrical postal code that produces a alternate(a) current of a desired frequency of oscillation.The inbuilt transmitter also has a system which changes some properties of the energy produced to take up a signal on it. This change could be as simple as turning the signal on or off. Change could be more complex such as alternating more knowing properties such as amplitude, frequency, phase or combination of all trey properties. The modulated electrical energy is sent via the transmitter to an antenna. Antenna changes the alternating current electromagnetic wav es this allows the waves to transmit in the air. There are drawbacks of using radio. First is attenuation can happen, this basically means the longer the wave has travelling to get to its coating the more weaker it gets. Most obvious example of this would be someone listening to FM radio in the midlands the move on he goes away from the midlands the more signal gets weaker. nukeAn electromagnetic base wave which has a range or wavelength of up to 30 gigahertz. presently atomizes are getting more popular due to advancing technologies. Microwave offers high bandwidth at low cost. Most common problem with microwave transmission is glintion. Microwaves are common used for radar which pickup planes and helicopters dissipated in the air. Microwaves will hit the plane or helicopter and reflect back and gets calculated giving the position of the flying object. Waves are reflected due to a barrier which stops the wave from going further so it hits the barrier and reflects back. Reflec tion affects the signal if the reflection is not mature then the reflection wont happen therefore a gone or a blank signal will be received. To disparage the effect try staying close the air. Wireless protocols such as Bluetooth use microwaves to transmit.SatelliteSatellite is a orbiting piece of hardware which has been left vagabond in the air from big companies like Microsoft, satellite can be used for communication. There are also other types of satellites which are used for spying or used for online maps such as Google maps, Microsoft live maps or another services. Satellites provide high bandwidth solutions. Satellite is categorized as a WAN because it uses high speed & long distance communication engine room which allows them to connect to computers. Attenuation also affects satellite conjunctive due to the same reason. If a satellite is not in the required position and starts transmitting signal it will not reach video so they ability not work properly or correctly. Satellite dish has to be in the same direction as the satellite. Satellite signals reach television using a transmission antenna which is located at an uplink mental quickness.The facility has an uplink satellite dish which would be around 9-12 meters in diameter. The bigger the diameter of the satellite the more accurate signals and better signal strength from the satellite is received. The satellite dish would be pointed towards the satellite and the uplinked signal is received by the transponder at a certain frequency. This frequency is normally C-band (4-8 GHz) or KU-band (12-18 GHz). The transponder then retransmits the signal back to the earth. NTSC, PAL or SECAM are tercet broadcast touchstones used through out the world. NTSC is normally used in the US, Canada, Japan, Mexico, Philippines, atomic number 16 Korea and other countries. PAL which stands for Phase Alternating Line is an illusion encode system which is used by over 120 countries in the world. In a few years time most of the countries will stop using PAL and any change to DVB-T SECAM It is sequential colour with memory is the analogue colour television system. SECAM was Europes first colour television amount and France currently uses it.The analogue signals for the three broadcasting types are transmitted via a satellite link scramble or unscramble. The analogue signal is a frequency modulated and change for a FM to something called baseband. The baseband fuses the audio and video sub carrier. The audio sub is further demodulated to provide a raw audio signal. Digital TVs that transmit via satellites are normally base on open standards such as MPEG and DVB-S. MPEG which stands for Moving Pictures Experts Group is a compressed format which code woful pictures and associated audio information. There is also MPEG 2 which is a digital television signal which is broadcasted via terrestrial cable and direct broadcast satellite TV systems. DVB-S which stands for Digital Video Broadcasting is a standard for satellite TVs which forward fault coding and modulation. It is used by each single satellite that serves a continent.Standards OrganizationsThere are difference types of standard organizations. These are the various types of standard organizations TIA/EIA, RS-232, IEEE, ISO, OSI and Manchester Encoding.ISO/OSI International Standards Organizations Open System Interconnect (ISO/OSI) is the standard model for networking protocols and distributed applications. ISO/OSI defines seven network layers.1. Physical2. Data Link3. Network4. Transport5. Session6. intromission7. ApplicationI will be only be explaining in-depth the first network layer Physical. This layer defines what cable or physical medium to be used. There are lots of different types of cable thinnet, mystifyingnet, TPC, UTP. All of these mediums are functionally the same. The major difference between the various cables is the cost, convenience, readyment and maintenance. Converters from one media to another operate at this level.TIA/EIA Telecommunications Industry overcometie & Electronics Industries Alliance (TIA/EIA), state the standards which should be used laying cables in a building or a campus. TIA/EIA describes how a hierarchical network topology should be laid out. A system where a main blow connect system is used and connected using a star topology using a backbone cabling through a mediocre or a horizontal cross connect. This type of cabling or comparable is also used for laying out telecommunication cables. The backbone cabling method will be used to connect the entrance facilities to the main cross connect. In areas such as office a horizontal cross connect for the consolidation of the horizontal cabling, which extends into a star topology. Maximum state horizontal cable distance should anywhere between 70M-90M. This applies to TTP ( depraved Pair Cable), but the fibre optic horizontal cabling has a set limit of 90M.IEEE pioneer of Electrical and Electroni cs Engineers allows the development of Electro Technology which in other words applies to electricity applied to technology. Societies like the IEEE Computer Society are subsidiaries of the IEEE itself. This standards organization also publishes journals. Devices such as digital camera need set amount of bandwidth speed so it uses a IEEE plug. all device that uses the IEEE standard uses a twisted pair cable. sign of the zodiacling StandardsNRZ- It stands for Non Return to Zero. It is a binary code normally used for slow speed synchronous and asynchronous transmission interfaces. Ones is delineate as a small voltage and zero is negative voltages. They are transmitted by either by set or constant DC voltages. It also uses additional synchronisation so it dose not lose any bits in the process.NRZ-L Non Return to Zero Level is similar to NRZ, but it not a binary code. Same as NRZ one is delineated as small voltage, but zero is also championed as a small voltage but it is not as bi g voltage as one, Therefore it allows more data to be send without a lot of signal change.NRZ-M Non Return to Zero abrasion again similar to NRZ, but one is actually represented by a change in physical state and zero is represented as change in physical state. This basically means that there is no voltage when there is no change in physical state.RS-232 This standard applies to serial data transfer such as the 9 pin serial connecters which are commonly used on a computer motherboard. The data is sent in as time serial publication of bits. Synchronous & Asynchronous is both beared by this standard. This standard and states the number of control circuits that can be or need to be used to connect the DCE & DTE terminal with one another. Data and control circuits which are signalled from a DTE connected to a DCE or vice versa will always unravel and operate in one direction this is called half(prenominal) duplex. Only full duplex allows data to be sent and received in both directi ons at the same time.Manchester Encoding Data bits which are represented by transitions from a logical state another is called Manchester encoding. This is a digital type encoding. In this encoding the signal is self clocking because the length of each data bit is set by default. Depending on the transition direction the state of the bit can be analyzed. In Manchester encoding the signal synchronizes itself. This is an advantage because this will decrease the error rate and optimize the reliability. But on the other hand it is also a disadvantage because the amount of bits sent in the original signal when transmitted has be doubly the amount of bits from the original signal.Differential Manchester Also known as condition Diphase (CDP). It is a encoding method which uses data and clock signal as fused to create a self-synchronizing data steam. Similar to Manchester encoding it uses present or absent transitions to represent logical value.TTL Transistor Transistor logic is a bi nary code which either uses high voltages between 2.2V and 5V to represent one and no voltages between 0V and 0.8V to represent a zero giveSpecificationMaximum Length/SpeedAdvantagesDisadvantagesCat.5 CableRJ45 Connector. make from Copper, PVC, fictileLength100 MSpeed100 Mbit/sCheapest type of cable,Mostly unshielded & more prone to electrical kerfuffle.Cat.6 CableRJ45 Connector. make from Copper, PVC, credit cardLength100 MSpeed 10 Gbit/sVery fast transmission.Unshielded & more expensive than Cat.5Cat.7 CableRJ45 Connector. Made from Copper, PVC, PlasticLength100 MSpeed100 Gbit/sExtremely fast and less interferenceIncredibly expensive and mostly likely be piece of musicufactured till 2013BluetoothMostly Copper for the circuitry, Plastic for casing.Length 100 MSpeed1 Gbit/s stake from cell phones, do not need wires to connect, Most of the phone are equipped with itOpen and other people can access your phone if not protected. Quite slow when sending and receiving on a cell phone. InfraredReceiver, Antenna and Transmitter, Copper & PlasticLength 40 kmSpeed 4 Mbit/sShorter wave than microwaves, not as harmful. slight interference.MicrowavesAntenna & Receiver.Length 1 MSpeed three hundred GHzGood for sending data over longer distancesDangerous, if something that uses microwaves e.g. cell phone for too long. Too much interferenceWi-FiWi-Fi Signal Transmitter.Length 95 MSpeed 5 GHzUsable anywhere in the house, can even be used as a hotspot in public places e.g. airports, caf, etcOther people can also access it so many connections can make it slow.SatelliteDish and a satellite in orbitLength 22,000 MilesSpeed 40 Mbit/sConnection from anywhere in the world.Delay of up to ergocalciferol msec due to rain or moistureFibre Optic take/Laser Connector. Glass, Plastic, PVC.Length 40,000Speed 10 Gbit/sExtremely fast speeds can be achieved without the use of switches, hubs, etc over long distancesSimply expensive to buy.RadioTransmitter & ReceiverLength 100 MilesSpeed 300 GHzAvailable anywhere in the world.Very limited range and gets easily change by interference.NameSpecificationAdvantagesDisadvantages concentric diam 6 mm / Resistance 85.2 kmCapacity 70 km at 1KHzCheap. 500 meters length. It very reliableexpensive and hard to installFibre OpticDiameter 2 microns. Good for transmission over long distance because it is immune to magnetic interference.Electrical interference protected. Stretches up to 3000 meters. No noise is generatedVery expensive and over time the sent signal will get weaker because of signal reflecting.UTP/Cat.5Foiled and uses sloven wire.Stretches up to 100 meters. Easy installation and transmission rates reaching up to 1 Gbps.Very open to interferences.s.t.p.Foiled and also uses copper wire.Shielded. Length up to 100 meters. Transmission rates between 10-100 MbpsExpensive heavy and big in physical size.RadioUses antenna to transmit. Signal can be refracted.No wires needed and very long distances capable.Signal gets weaker the more time taken to reach the destination. Security is a problem very open for hackers.LANThis is type of network which covers a small office, home or a school network. A LAN uses either wired Ethernet or wireless RF technology. Using a LAN can be much easier when there is a printer visible(prenominal) or sha besiege a buck throughout the network. Updating parcel system is much easier because updating software will automatically update all the other softwares. LAN has much higher transmission rates because it is wired connection rather than wireless. Ethernet and Wi-Fi as most greatly used technologies, however many others such as keepsake rings have been used before. This relates to standard IEEE 802.2.This standard allows two connectionless and one connection orientated operational mode Type 1 which allows frames to be sent to a single destination or multiple destinations on the same network is a connectionless mode. Type 2 is the oriented operational connection mode. In th is mode it uses something called sequence numbering which makes sure that when the data is send it gets to the destination in the correct order and not a single frame has been lost. Type 3 which is also a connectionless service, but only support point to point communication. Infrared is related to this service because in computer infrared network it can receive and transmit data either through the side of the device or the rear side of the device.When connections are made using Microsoft Windows Infrared the same method used for LAN connections can be used. Infrared technology has been extended to allow more than two computers to be connected semi permanent networks. The advantage of a LAN is that the same physical communication path can be shared by multiple devices. For example it there is a printer, a computer and the internet connection the LAN will allow connections to the printer and it will also allow connections to the internet. If a software is loaded onto the file server t hat all the computers on the network can use it. There are quite a few drawbacks of a LAN network. For example security measures need to be taken so that users cannot access unauthorized areas. It is quite hard to setup the network. Skilled technicians are needed to swan the network. Yet the biggest disadvantage is that if the file server goes down than all the other computers on the network are impact as well.WANThis type of network covers a wider area. It is used over high speed, long distance communications such as computers in two different areas. A WAN can also be shared. For example two occupants in two buildings can share the wireless connection to a tertiary person, or a business or anyone or anything they wish to do so. Data is safe, batten down and quick when it is transmitted between two computers. WAN can also be used to connect different types of networks together for example a WAN network connected to a LAN networks. The reason behind this is that it is AppleTalk. It is a cheap LAN architecture which is a standard model built for all Apple Macintosh computers and optical maser printers. It also supports Apple LocalTalk cabling scheme as well as Ethernet and IBM token ring.AppleTalk can connect to standard computers which do not have AppleTalk. This all relates to FDDI standard which stands for Fibre Distributed Data Interface. It is a backbone of a wide area network. It uses fibre optic cable to transmit data up to supported rate of 100 Mbps. An advantage of a WAN it allows secure and fast transmission between two computers. Data transmission is inexpensive and reliable. Sharing a connection is favorable as well because it allows direct connectivity. A WAN also allows sharing of software and resources to other workstations connected on the network. Disadvantage of a WAN network is that the signal strong all the time so anyone trying to hitchhike a connection can use the WAN connection it is not protected. WAN are slow and expensive to set -up. They also need a good firewall to stop intruders using the connection.Networking MediumsDifferent types of medium are used for different types of topologies.Coaxial CableIt is normally used to connect telecommunication devices which used for broadband connection which use high transmission rates to transfer data. The cable is insulated using a braided shield which is also known as a screen. It protects the cable from electromagnetic interference. It has higher capacity than a standard copper wire. Therefore it allows radio frequencies and television signals to be transmitted. Various types of concentrical cables are available which can be used for thin Ethernet which are used for networking 10Mbps connections lengthening up to 200 meters. There is also thick Ethernet cable is also used for 10Mbps connections but stretching up to 500 meters. Unshielded Twisted Pair (UTP) coaxial cable has been used in the past when building networking using thick or thin Ethernet. Ethernet ca bles quite expensive but they are still used because they carry more data then a telephone wire and it is less persuasible to interference.Optical FibreOptical fibre also known as a fibre optic cable uses light to transmit data. get by is made using a laser or LED is sent down a fibre which is thin strand of glass. Fibre optic is about 2 microns in diameter which is 15 times vaporous than a single human hair. Optic fibre is not affected by electromagnetic interference. It is cable of higher than data transmission rates, idol for broadband usage. Fibre optics are manufactured in two different types the single mode and multi mode. The difference between the two is quite obvious single mode uses one beam of light to transmit data to longer distance of around 3 km but the multimode uses multiple beams of light to transmit data but only to shorter distance of 2 km. This allows more data to be sent at the same time. It is normally used for broadband transmission as mentioned before b ecause it is faster at transmission than any other cable currently available. Fibre optic also has an advantage of long distance transmission because light propagates through the fibre with secondary attenuation compared to electric cables. Not many repeaters are needed for long distance. Data travelling using the fibre can reach rates of unto 111 Gbps. Fibre optics also restrict high voltages travelling from end to end of a fibre to another end. It also restricts cross talk and environmental noise between signals transmitting to different cables.UTP (Unshielded Twisted Pair) & s.t.p. (Shielded Twisted Pair)UTP and STP both use copper wires which are known to man as one of the oldest types of transmission media methods. STP is insulated with a metallic formative foil which is all under the plastic sheath. This insulating is expensive to make thats why it is more expensive than normal cable. Even though STP cable is shielded there is still crosstalk. It cannot be eliminated. Both U TP & STP individual wires are twisted together so it creates there is less crosstalk. Core of each of the type of cable is a very good conductor and easy to work with. Media which can be used with UTP is internet, because it is easy to install, maintain, less expensive and allows higher transmission rates. The media used with STP is also internet, but it is more expensive and difficult to install. The advantage is that there is less interference. It is difficult to install because it has to be grounded at both ends. Improper initiation will result I metallic shielding acting as a antenna and it will pick up unwanted signals. imputable to the cost and difficult to install and maintain it is hardly used in Ethernet networks. It is mainly used in Europe.crosstalkCrosstalk means that signal that are transmitting in different circuits interfering with each other. Crosstalk happens because unwanted signals interfere with another channel transmitting undesirably.Electrical hinderanceNois e is when an electrical signal is transmitted across a wire which is not the sent signal by the user, but it is another signal which has been picked up randomly. Twisted pair cables eliminate the interference because they are twisted with each other so they cancel out each other. The burdensomeness and varied insulation of a cable and its capacitance of the wires will cause noise. For example when there is communication on a telephone and either person cannot hear the message clearly this is caused by noise affect the signal. This is known as crosstalk, as mentioned before crosstalk is when signal is affected by electromagnetic field around a wire. Electric noise cannot be eliminated but can be minimized by fetching caution. Keep cables away from electrical equipments and shield the cable weather it is a fibre optic or a STP.ChecksumIt is a method used for error-checking the received data against a calculated checksum. For example when a data is received by the designated node th e checksum error detection method will create a new deliberateness and check it against the old calculation to check weather the same result it received. This makes sure the data has not been altered in any way when it was transmitting. The checking of the data is called checksum function or checksum algorithm.Cyclic Redundancy Check (CRC)CRC is another type of error-checking technique used in data communication. A CRC character is generated at the end of the transmission. The produced CRC characters value depends on the hexadecimal value of ones in the data block. The node receiving the transmission makes a similar calculation and compares it to the source node and it the values are different then it asks for retransmission of the data.FrameIt is a entreaty of bits sent over a medium. It contains physical address and control information. It also contains error-detection methods like CRC. The size and role of the frame is all dependent on the type of protocol, which is often used synonymously with big money. When the data is split and if needed it is sent to Ethernet frame. The size of the Ethernet frame varies between 64 and 1,518 bytes. It uses the IEEE 802.3. It contains address, length, data and error checking utility. The data is passed onto the lower level components corresponding to OSIs Physical layer. This converts the frames into bit-stream and sends it over the transmission medium. Other network adapters on the Ethernet receive the frame and analyze it for the destination address. If the destination address match of the network adapter, the adapter software simply processes the incoming frame and the passes the data to higher levels of the protocol stack.PacketsIt is a unit of data sent across networks. When a computer transmits data it will split or divide it into packets when it reaches the defined node it is transformed into the original transmission. Also known as a datagram it contains two parts. The cope which acts as a envelope and the o ther part is the payload which is contents. Any message sent over the size of 1,500 bytes is fragmented into packet for transmission. When packet filter is put into place the header of incoming and outgoing packet is analyzed and decides whether to let them pass or restrict the packet, this is decided based on network rules.Data Transmission Modes & MethodsThere are three different ways transmission can take place. Data transmits either using simplex, half duplex or full duplex mode. There are two different ways how data is transmitted. Data can be transmitted via serial or via parallel transmission. unidirectionalSimplex data can only travel in one direction. video recording and radio broadcasting are example of simplex. Fibre optic works with simplex mode. Simplex is good for satellite communications. TV signal is the certainty that satellite communication is good because the transmission is good and clear. Simplex is seldom used for computer based telecommunications.Half Duplex Half duplex data can travel both ways but only in one direction. Coaxial cable works in half duplex mode. Radio is a example of half duplex because the signal reaches the destination and comes back to the original source. Communication between networks also works at half duplex. If a node is transmitting a message and another node wants to transmit it has to wait till the token ring comes back.Full DuplexIn full duplex data can travel in both directions and at the same time. The bandwidth is divided in both directions. UTP/STP mediums work at full duplex. For example Bluetooth is a full duplex because data can be received and sent by both devices. Another example is landline telephone because both end of the phone can speak and listen to each other. sequential TransmissionIn serial transmission one bit is sent at a time. It is good for communication between several participants. accompanying transmission is slow. When the data is sent it is dissembled by the source and reassembled by the receiver. match TransmissionParallel transmission is when every bit is sent simultaneously but using separate wire. Basically when data is parallel channel transmitted for i.e. 8 bits or a byte everything is sent simultaneously therefore its faster than serial because serial channel would send the 8 bits or byte one by one. Most common example is communication between a printer and the computer.