The Geometric Arrangement Of Computer Systems

The Geometric Arrangement Of reck unrivalledr SystemsA meshing a great deal simply referred to as computer cyberspace, is a collection of computers and devices bonded by converses channels. Computers on a engagement argon virtually sequences retrieveed nodes. In in realiseation applied science meshing is series of pictures or nodes inter affiliated by chat paths. These talk channels facilitate communicatings among drug users and al commencement users to manage re cites with otherwise(a)wise users.Net whole kit and caboodle may be classified according to a huge variety of characteristics.Topology The geometric arrangement of a computer ashes. The most common network pull inology or general configurations of networks include theBus topologyStar topologyToken ring topologyNetworks stern similarly be characterized in terms of spatial distance A meeting of two or to a greater extent computer governing bodys liais sensationd together. thither ar m every t ypes of computer networks, includingLocal- atomic offspring 18a networks (LANs) In this type of network the computers linkedinside the organization.Wide- atomic number 18a networks (WANs) The computers be farther apart and be connected by diametric communication channels.Metropolitan- ara networks MANs) A info network designed for a townspeople or city.Campus-area networks (CANs) The computers are within a express geographic area. lump campusHome-area networks (HANs) A network contained within a users home that connects a persons digital devices. network communications communications protocolsBefore going to Internet protocols start-off we have to live about the protocol.Protocol The protocol defines a common driven of rules and signals that computers on the network use to communicate.The Internet Protocol (IP) is a protocol use for communicating entropy crossways a mail boat-switched lucrework using the Internet Protocol Suite, likewise referred to as transmission control protocol/IP.The Internet Protocol is responsible for addressing hosts and routing datagram ( mailboats) from a source host to the destination host crosswise one or to a greater extent IP networks. The direct of computer softwares from source to destination is performed based on two types of networksThese networks include fit out networkA wired network is a physical system that al minuscules multiple computers communicate with each other. Wired net on the job(p) is unremarkably accomplished by using cables and other hardware to connect one computer to a nonher. at one sequence a wired home network has been installed, users within the network bunghole share computer records and documents as healthy as printers and scanners. In This network the software packages are transferred by using transmission control protocol/IP.Wireless networkConnecting one computer to a nonher computer is identifyed network. We are connecting these computers to transfer tracts from sou rce to destination. But we are using wireless network, rather of cables we are using radio waves to transfer these packets by using UDP (User Datagram packet).transmission control protocol/IP ArchitectureInternet protocol suite which measuringized for the stainless networking environment describes specific rule guidelines for communication strategy. This protocol architecture deals with communication among source and destination which subject matter how the data should be formatted, how the packets should come out the address of the receiver and how the packets are transmitted from source to destination.In this transmission control protocol/IP architecture the data should be transferred in the form of packets from source to destination. The transmission of packets starts from source and these packets transmits through opposite types of horizontal surfaces and finally it march ones the destination. In this architecture there are 4 antithetical layers, each layer performs it s own functionality to reach destination.In this architecture each layer sends the information to the lower layer to cross the functionality of that layer, after completion of processing the information passed to lower layer and so on. This process repeats till the packet should reach the destination.The 4 different layers of TCP/IP protocol architecture and each layer is described underApplication LayerThis layer provides the well-nigh functionality to perform different go of the lower layers. And this layer provides different protocols for the purpose of exchanging data surrounded by different layers. The protocols which are defined by use layer are cognise as application protocols and these are utilise to exchange the informationThere are different protocols employ in application layer are described as followsThe Hypertext transportation Protocol (HTTP) This protocol utilise in application layer which is utilise to perform the transmission of files among the network. The File raptus Protocol (FTP) It is in any case one protocol used in application layer to perform the transmission of interactive files.The Simple Mail Transfer Protocol (SMTP) by using this protocol the transmission of mail messages and file attachments are done.The functionality of application layer similar to the functionalities of OSI Application, Presentation Layer and school term Layer. post LayerThis is the game layer of TCP/IP protocol architecture. This Transport layer deals with Transmission match Protocol (TCP).This protocol is used to know the status of packet transmission whether it reached the exact destination or not. Before reaching the destination it performs the error checking which means it is in the expert order or not.Network LayerThis is the one of the grave layer of TCP/IP protocol architecture. In this layer it deals with the Internet protocol (IP).The communication of these layers should be done by using this protocol.Network assenting LayerThe netw ork access layer is the combination of Data link layer and physical layer. The Data link layer deals with the transmission of data packets across the architecture. This Data link layer provides different functionalities like change the data in packets, error detection and the flow of data from source to destination. And coming to physical layer deals with the physical medium much(prenominal) as voltage levels, connector types and handshake procedures.TCP/IP Protocol LayersChapter 2In chapter 1, I have in the main discussed about the VoIP and brief organise of dissertation. This chapter helps in agreement the VoIP system, key components, and protocols. It is dear(p) to understand the concepts and the technology when working on a new system.2.1 OverviewThe generations have changed, so the way of communicating to your family, friends has changed. Not moreover type is a concern but low greet is also an important chemical element for making calls. These are the few things whi ch brought a lot of research work for division all e genuinelywhere meshwork protocol (VoIP). VoIP is a way sending constituent packet over the profit. VoIP not only provides cheap calls but also provides better flavor than before.2.2 What is VoIP?VoIP is one of greatest invention in human winsome it essentially allows transmission of human voice in the form of digital packet over a network. It is in essential due to lower call rates, implementation on a existent network, better fictitious character than before. many people, governances have been consistently working on this technology to get a better process of the returns. This technology could be also implemented in a topical anesthetic area network. The process involves compressing and digitization of voice and transforming into Internet Protocol packets and sending the format over network. This is the process which is cognize as Voice over Internet Protocol (VoIP). 42.3 VoIP HistoryComputer to Computer avocation begin in Israel in 1995 by vocaltech parcel by adduce internet scream. This software was designed and used to carry Voice calls 8. The whole system consists of basic things such as s beakers, modem, and cloggy cards. The voice signals were digitized, turned into voice packets, so that they could be travelled over the network and in the end, packets would be shifted back into voice signals. The overall lumber was not at all good and not fifty-fifty bordering traditional phone calls. But still it is considered as a major(ip) milestone as it was birth of new technology. The designed software had to be installed on both systems ( troupe and receiver) to process the voice call. Therefore it was the birth of first IP phone.Later after few courses in 1998, number of private companies, organisation started working and using this technology more effectively. It is invaluable assets as it is due to provide cheap long distance calls, repress laid-back charges with traditional phon e system. These companies were able to design and organize VoIP doors on the internet, which would allow cheaper calls through Computer to Computer and also from regular phone to phone. This enhancement brought more awareness of the technology, market profits among private organisation and investors. However on the other side general people were unvalued with the technology due non availability of high speed internet data link in most of the areas. This was one of the main reasons that it couldnt get popular quickly. Enterprises, beautiful organisation already started using the benefits of VoIP communication with voice across the networks was deployed and used. As meter passed more standards and protocols were introduced for better quality as VoIP in low stages was not a good quality 4.In initially stages when it was introduced, it was not considered as a potential technology. In some parts of northbound America it was offered free, which allowed free phone calls using regular phone. Though it was not considered potential technology, it was slowly getting popular and accepted in assorted areas such as enterprises, general public. last it was a well cognise model by 1998, where VoIP was used about 1% of voice profession and in just two years of magazine by the year 2000, it was used over 3 % of traffic. This growth was mainly due procession in the system. 10. VoIP is rapidly growing year by year. It is likely to reach around 300 million users of VoIP around the world.2.4 ProtocolsA protocol can be defined as a combination or set of rules. These are necessary for data transmission by two or more computers over a network. These protocols determine data compression, acknowledgements, and error checking methods. 122.4.1 Internet ProtocolInternet protocol is the primary network protocol used across the network. By using this protocol the packets are sent across the network.It is a conjunctionless protocol which means each packet is travelling in the netw ork is independent and is not related to any other unit. The conjunctive oriented protocol transmission control protocol (TCP) handles all the packets.2.4.2 H.323The H.323 is one of the two important protocols used in VoIP. H.323 protocol is a standard designed by international telecommunications union (ITU), which sets rules for mul cartridge holderdia system applications across the network. It is used for sending audio recording, data packets, and video over IP network, which basically means providing square time multimedia applications. It behaves as veridical time protocol and also non hearty time protocol. 6.Most of the ITU-T terminal recommendations provide only terminals. However H.323 provides divers(a) components along with terminals on a network 13. They are gateway, gatekeepers, and multiple control units. These components provide forefront to point/multipoint multimedia communications, when connected together. Below is the figure of H.323 architectureFigure 1 H.3 23 architecture referee 132.4.2.1 H.323 terminalThe H.323 terminal is also cognise as invitee usually it is a computer or internet phone with H.323 client. The H.323 terminal shake ups real time bidirectional video, voice, data interactions. H.225.0 is used to specify call signalling, packetization, synchronizations. On the other side H.245 is used to specify messages for opening and closing ratiocinative connections beside other commands 14.2.4.2.2 Gate keeperGatekeeper supports address translation and other access control for H.323 standards. H.323 is the standard that points the system this protocol provides different types of dish out such as voice, video and packet transmission. A gatekeeper acts as routing manager, which is responsible for all end nodes in a particular area. 112.4.2.3 penetrationGateway is a part of the VoIP system, which is used to modify audio and fax call in real time. Mainly it works between internet and plain old telephone system as a converter. This IP telephone set gateway converts analogy signal into internet data packets and sends data as a regular data packet over a network. Once the packet is received on the receiver end, it is re born-again into analogy voice signal. It allows regular telephone calls to be achieved through the internet and provides communication between Private Branch Exchange (PBX) and internet.152.4.2.4 Multi Point Control UnitsMultipoint Control Unit (MCU) acts as a multipoint conference to establish a connection among three or more devices and gateways. It is usually integrated with a client , gateway. There are two elements associated to MCU, one is multipoint controller and second is multipoint processor. In this multipoint conferencing, two types of stages involved, centralized and decentralized. Centralized multipoint mode provides direct communication of H.323 devices to MCU in P2P method. Multipoint controller is used in a point to point call way and moreover it is also used to check if i t has to multi suck or uncast the information such as audio and video. In the other mode decentralized multipoint, multicast method is used to transfer all data to other devices. The multi point control unit checks the readiness of all devices and sends different data streams 16.2.4.3 SIPIt is a protocol used for modifying, terminating, establishing sessions over a network. It is also called as signalling protocol and mainly used for internet phone VoIP calls. It is designed by the internet engineering task force (IETF) for real time transmission. There are different components in SIP.SIP is less heaviness than H.323 and moreover when it comes to flexibility, it is more flexible 17. It can also used for video, audio, multimedia sessions. It is more popular and being adopted more due to more flexibility than H.323. The structure of SIP is resembling as of Hyper Text Transport Protocol (HTTP) it follows the client server model 182.4.3.1 Main Components involved in SIPUser AgentUse r Agent works as logical entity at SIP end station software. It acts as client when initialising session requests and acts as server when replying to a session request. It has the capabilities of initiating and answering calls. It also has the ability to save and manage call state that is why it is known as intelligent 4.Proxy hostThey are used as computers and requests are forwarded by them on the behalf of other computers. They are one kind of intermediate server, forwarding requests from the user to SIP server 4.Figure 2 an example of proxy server Ref 4Redirect ServerIt is a second type of intermediate server. The main responsibilities of this server is to give name resolution and user mess. It simply gives the information needed to start the originating client. Once it has been done, it is no more involved in the process 4Registrar ServerRegistrar Server is a server that is used to register the location information from the user agent and saves the registration information. Th is sort of concept creates a directory for all logged and also specifies their location.42.5 QOSQOS is Quality of Service refers to the capability of a network to provide better service to selected network traffic over various technologies, including Frame Relay, Asynchronous Transfer Mode (ATM), Ethernet and 802.1 networks, SONET, and IP-routed networks that may use any or all of these underlying technologies. The primary goal of Qos is to provide precession including dedicated bandwidth of service is most important part for any multimedia application. It is more considered in a private network such as connection of multiple offices than on worldwide internet. Initially, internet was known for sending email and file. However it is more than just sending files, now it has real time applications such as video, gaming, internet telephony. As the VoIP technology has evolved so much, there is more need for better Qos.Below table provides a list of Qos parameters 19For a successful VoIP deployment, Qos is an important tool. Bandwidth is one of important factor in VoIP, if enough bandwidth is provided the voice quality lead be more than just satisfied. This is the reason go in organisation doesnt need plotted QOS as they have enough bandwidth. A successful VoIP deployment requires a paying attention examination and network assessment, as well as a system to mea for certain and monitor the system in order to benefit from the cost nest egg, flexibility and functionality VoIP offers.There are five areas to consider when planning a VoIP deploymentMake sure the network can handle VoIP.Keep the deployment simple. bring out network service maps and update service-level agreements.Consider QoE. Quality of experience (QoE). Review, reassess and repeat.However as the network grows such as internet, more complications, issues boot out as there are multiple go to be handled, some(prenominal) areas are to be covered, security is concerned. The aim is quite simple, IP te lephony must meet the requirements of a user, which means voice quality should be similar to that of PSTN in such a way to retain same standards and satisfy the user expectations. When the voice signals are transmitted over the network, the data is divided into packets and transmitted across the network through network elements such as routers, switches. In this process to achieve better results, Qos is to be followed which would give importance to real time application over non real time applications.20. The main factors network analysis are mainly wait, jitter (variation in slow down), and packet loss.Packet Loss single of the very important factors in VoIP Qos is packet loss. This generally occurs when the packet is dropped during peak loads and congestion. This happens as VoIP packets are very sensitive of voice transmission. The main reason or largest cause of a packet loss is a packed being dropped due to congest in the network. This is the main factor which can significant ly affect VoIP quality 22DelayDelay is the key deed of QoS , which is needed to be lessen . quit to end moderate is the duration taken by a analog signal to transmit from the sender to receiver. Delay does not induce noise , up to now it affects the quality of confabulation. When the agree reaches about 250ms, the telephonic conversation observes its impact. Between 300 ms and 500 ms the talk gets fairly difficult. Finally if it reaches above 500 ms makes an impossible communication. In VoIP the custody could be anywhere between 50 to 100 ms , however in POTS , the decelerate is generally under 10 ms.22JitterDelay innovation sometimes also known as Jitter is the variation in packet delay. It is mainly the difference value between the delay of two incidental voice packets. In the internet terminology they can explained in a simple manner , if the packet n has delayed highly whence chances are high for the packet n+1 also21. To reduce the delay between two queuing packet s, a jitter buffer is used. This buffer stores arriving packets temporarily in order to reduce the difference value between two packets. For some reason, if the packets are delayed and so it simply discards the packet. The acceptable value considered for jitter is between 0ms and 50ms and anything above this is not acceptable 18 doneTechniques for jitter absorption1. same playout time is set for all packets for whole session or for the duration of onesession.2. The second technique involves adaptive adjustment of the playout time during silence catch related to give way network. This technique is also called as talkspurts adjustment.3. This technique is also known as within talkspurts adjustment. In this method constantly adapting the playout time for each packet, which needs the scaling of voice packets 152.6 Initial VoIP Study and practiceThere are various real time applications running on internet, such as calling over PC, Video and voice. When deploying these work across ne tworks, there are many difficulties and issues are faced. Some of them are direct related to QoS is the network capable of handling the new application and whether there will be any negative impact on existing services in the network. For real time application such as VoIP, which uses UDP as transport layer protocol, QoS is not guaranteed. Researchers are always working on these issues depending upon the real time application. In order to achieve good results, a good policy , QoS should be implemented. There are many things to be considered to give a high standard service. To begin packetization , delay , network design are few things to establish QoS.7 However other things are signalling protocol , security, bandwidth, power failures. Certainly there are numerous methods available to achieve QoS. But it is really important to understand and project the requirement of this QoS by a particular system. Sometimes it is noticed by the engineers that spending on the network parameters is less than on QoS. As a result, it is important thing to consider before deploying, whether to design a QoS or not.2.7 Components of VoIPBelow figure gives an end to end VoIP system Components from sending point to receiving point. As seen in the figure the different components involved are encoder, packetizer, playback buffer, depacketizer , decoder. Voice is in the form of analog , which moves along the time , which usually is limited within 4kHz. Bandwidth 18. The analog or audio signal is first reborn into samples , which is a digital signal , which is then transmitted across the network 17. Next to encoder it is packetizer , which encapsulates the digital samples into packets along with real time protocol (RTP),User Datagram Protocol(UDP),IP and Ethernet headers. Finally the digital packet moves into the network and passes through playback buffer. Playback buffer mainly used to absorb any kind of changes, delay. In final stages the packet enters depacketizer and then decode r which convert the digital signal into analog signal.Fig 3 source Assessing the Quality of Voice Communications Over Internet Backbones 17 .2.8 CODECA codec is software that converts analog signal into digital bits and transmits them as data across the network. These Codecs use high level methods for coding 12.Table 2 2.9 consummation related QoS parameters.One of the most important metrics for QoS in VoIP is bandwidth. It plays an important part as the voice channels rely on the present bandwidth. Apart from this constraint, there are other important factors which also fall the quality of calls they are loss of packets, delay and other variations.End to End delayIt can be explained as the duration taken by the information to pass from the speaker or caller to the receiver. VoIP requires real time traffic transmission across the network and this transmission end-to-end delay is most important factor to decide QoS. ITU-T suggests that end-to-end delay should be less than 150ms fo r a high quality conversation 12BandwidthThe bandwidth required to make a single call in one way is 64kbps. If the call is using G.711, the codec samples 20ms of voice for each packet. We need 50 packets to send per second. In addition to this packet, other headers of protocols are also added. They are real time protocol, user datagram protocol, internet protocol and Ethernet. In the end 226 bytes must be transmitted 50 times per sec. This value is only for one way. The full(a) required bandwidth for each call is 100pps for both directions 19.Call DistributionOne of the very important factor before planning or conniving is the calculation of internal and external calls. The call usage statistics plays an important role in VoIP deployment. The statistics would give a clear picture of nature of call, time, duration, peak time. In order to achieve best QoS , always a thrash scenario should be considered. Like, busiest call transmitting time should be considered of the month. This wo uld make sure that all other calls are provided with well planned QoS.2.10 Advantages and DisadvantagesThere are many advantages associated with VoIP, oddly when compared to PSTN it gives various benefits. The good thing about this technology is that it is not only beneficial to small and large enterprises but also for residential users.Low costMost of the VoIP companies provide low calling cost for distant places, which are almost same as local call. Only condition is that the user must have broadband connection to use the VoIP service. Now a days most of the places such as homes, offices are equipped with internet connection. This is the main advantage with VoIP technology, as it does not need a completely new system to make cheaper calls. In some situations the calling cost will be absolutely free, even though the call will be an international call. Lets take the scenario where the user is using his or her computer connected with internet. In this process the user just needs sof tware installed on the computer and also at the receiver end, software must be installed. The entire conversation between these two computers is free of cost.Multimedia ApplicationsApart from regular international calls VoIP service also provides unified messaging, real time applications such as audio and video conferencing, e-learning and other entertainment applications. VoIP has brought number of new things in the internet world.Corporate benefitsVoIP, or Voice over Internet Protocol, is rapidly fair a top choice for people wishing to avoid costly telephone service. For this reason it became more popular. The following are three top reasons for using VoIP. The reasons areHuge savingsOptionsIts Not Going anywhereVoIP calling can significantly remove all international charges for companies making distant calls overseas. These savings can be also included when calls are made within the organisations. But when it comes to international calling more savings are achieved. Especially for companies with data networks have an edge over the technology. With modern improvement in VoIP quality, call can be compared to PSTN and used as regular method of calling.DisadvantagesHowever, there are still some disadvantages of VOIP especially when it comes to using the technology for functions beyond the one caller to one caller scenario. one of the disadvantage is If multiple users need to make VOIP calls, it can be difficult for the company to know exactly how much bandwidth to provide especially if internet access, video conferencing or other data transmission services are using the same path.Broadband connectionA high speed internet service is necessary to run VoIP service it is relevant for both enterprises and residential. If the internet speed is low, then quality of VoIP may degrade. top executive outageOne of the major drawbacks of VoIP is disconnection of service in power outage. Whereas PSTN works even when there is power outage. Comparatively PSTN is more rel iable in such situation. However this situation can be controlled in VoIP by using generators to provide power.Chapter -3Literature ReviewRelated WorkIn order to provide more security the usage of VOIP network deployment is increased. Because of low price calls most of the enterprises uses network, it causes network congestion. To avoid network congestion we best-loved VOIP network deployment system. After many researches, VOIP is issued in both wire and wireless. The demand of VOIP service has increased because of its security, performance, quality of service (QOS) and network infrastructure enhancement. This chapter mainly focused on research papers on VOIP deployment and present studys of performance and quality of service (QOS) measurements.3.1 VoIP Network SecuritiesIn general there are always problem with network attacks like denial of service, worms, network attacks which can be made by man and etc. similarly VOIP system can also faces the attacking problems and degrade the performance of voice services. here we need to prefer intruder detection system which can handle the network oriented attacks efficiently. Even we will get attacks like spams on the mailing system. The main aim of denial of service is to interrupt the services from resources by making them unavailable to the user.Multi-Layered VoIP SecurityBecause of threats attacks the quality of voice will be degrade, it causes the service useless. Denial of service and distributed denial of service attaches degrades the quality of voice.VoIP service introducing the greatest achievement by providing security in communication by control (signaling) and content (voice) parallel channels which together form the VoIP service. The attacks damage the whole service useless.3.2 VoIP network PerformanceIn communication world , a lot of research work is going on to evaluate VoIP performance by analyzing different inputs such as traffic, packet delivery time, receiving time, jitter and network congestion. I n the reference 4, the author designed a network model using computer simulation. This research explains the network performance in respect to various available links and network.The VoIP performance revaluation shows the loss patterns in terms of packet loss, delay time and network congestion, it measures the delay and loss characteristics. Kostas 5 deliberated the VoIP performance on different networks and they discuss the delay and loss measurement characteristics, they discuss founded on round trip delay measurements. The quality results can be seen with the delay and packet loss.3.3 VoIP Quality of operateVoIP services are gradually adapting in to new level of services and used by different sectors. Currently there are some challenges for this technology. Anyone providing VoIP services should be able to achieve certain standards and quality of the service should satisfy the user. The availability of QoS is an important factor for the end users. Therefore understanding the iss ues related to QoS is one of the important factor , QoS parameters should be properly analysed and if any loop hole is found , it should be accordingly rectified. Cole et al. 6 propose a quality measurement method by studying the check over on E-Model 7 by measuring the quintiles of delay and loss. Markopoulou et al. 8 employs subject quality measures to review internet backbone ability, this work is based on packet tracer bullet which are able to present overall quality of VoIP. In this