Classification Of Network Topology

Classification Of Network Topology The term topology refers that way in which the end points, or stations, attached to the network are interconnected or it is the arrangements of systems in a computer network. It can be either physical or logical. The physical topology refers that, how a network is placed in a physical way and it will include the devices, installation and location. Logical topology refers that how a data transfers in a network as opposed to its design. The network topology can be categorized into bus, ring, star, tree and mesh. Hybrid networks (They are the complex networks, which can be built of two or more topologies together). Bus Topology A bus topology is characterized by the use of a multi point medium. A long and single cable acts as a backbone to connect all the devices in a network. In a bus topology, all computers are stations attaching through the tap (an interfacing hardware to connect to the network) and it connects directly to the bus network. Datas are transmitting and receiving to the bus, by the duplex actions between the tap and the device. Devices in the bus topology send a broadcast message to the other device for communications. But the proposed device can only accepts and processes the messages. Advantages Bus topology can install very easily on a network. Cabling will be less compare to other topologies because of the main backbone cable laid efficiently in the network path. Bus topology suited for a small network. If one computer fails in the network, the other computers are not affected they will continue to work. It is also less expensive than star topology. Disadvantages The cable length will limited and there by limits the number of stations. The main cable (backbone cable) fails, and then the entire network will fail. It is very difficult to trouble shoot. Maintenance cost is very high in a long run. Terminators are required for both the ends of the cable. Ring topology The ring topology is the network consists of dedicated point to point connection and a set of repeaters in a closed loop. Signals passing through ring in a single direction until they reach to its final destination. It may be clock wise or anti clock wise. Datas are transmitted in the form of frames. These topologies are used in school campuses and some office buildings. Advantages It performs better than star topology under heavy work load For managing the connection between the computers, there is no need for the network server. It is cheaper than star topology because of less wiring. By adding the token ring in the network, can create large network. Very order network because all the devices has a access to the token ring and opportunity to transmit. Disadvantages A failure or break in the ring, it can disable the entire network. It is much slower than an Ethernet network with under normal load. Any moves, changes and ads of the devices can affect the network. Network connection devices like (Network adapter cards and MAU) are much more expense than Ethernet cards. Star Topology Star topology is the network in which each station is directly connected to a central connecting node called hub. In star topology all the devices are not directly connected to one another. All the devices are connecting to the central server (switching hub). This topology does not enable the direct traffic between the devices in the network. A controller act as the interface between the devices. A star topology feature, each device needs only one link and one input/output port to connect the number devices in the network. This type of topology is used in local area networks (LAN) and sometimes high speed LAN often uses a star topology with central hub. Advantages If anyone connection is fails in the network, it will not affect the entire network. Only that connection or link affected. It is easy to identify the fault and fault isolation. Easy to expand the network in the star topology. No failure to the network when connecting or removing devices. It is very easy to manage because of its simplicity in the function. Disadvantages In a star topology, if the central connecting device goes down, the entire network will fails. It requires more cable length compared to the linear bus topology. Star topology is more expensive than bus topology because o the connection ports like hub. Tree Topology Tree topology is the generalized form of the bus topology. It integrates the multiple star topologies together on to a bus. The data transmission of the tree topology, through the cables with closed loops. The transmission medium is a branching cable with no closed loops. The layout of the tree topology is beginning at the head end. These layouts have many branches and these are quite complex layouts in the topology. Any transmission from the device is going through the medium and it can receive by all other devices in the tree topology network. Tree Topology will give the expansion of the existing network. Advantages Tree topology is well supported by the hardware and software vendors. Point to point wiring for each and every segments of the network. It is the best topology for the branched networks. Disadvantages It is more expensive because more hubs are required to install the network. Tree topology is entirely depends upon the backbone line, if it fails then the entire network would fail. It is very difficult to configure and wire than other network topologies. In a tree topology, the length of network depends on the type of cable being used. Mesh Topology In a mesh topology, every device has connected to each other or a dedicated point to point link to every other device. (Dedicated term means that the traffic links only between the two devices it connects). To find the number of physical links in a fully connected mesh network with n nodes, we first consider that each node must be connected to other node. Node 1 must be connected to n-1nodes, node 2 must be connected to n-1nodes, and finally node n must be connected n-1 nodes. If each physical link in the network can allow the communication in both directions, we can divide the number of links by 2.In other words we can say that in a mesh topology, we need n (n-1)/2. Suppose if we are connecting 15 nodes in a mesh topology, then the number of cables required; CN = n (n-1)/2 CN = Number of cables = 15 (15 1)/2 n = Node = 15*14/2 = 15*7 = 105 Therefore, the total number of cables required for connecting 15 nodes = 105. Advantages There is no traffic problem because of the dedicated link in the mesh network. Mesh topology is very strong. If any link becomes not active it does not deactivate the entire system. Point-to-point links make full identification and fault isolation easy. Security or privacy for data travels along the dedicated line. Network can be expanded without any disruptions to the users. Disadvantages Installation and reconnection are difficult. Mesh topology required more cabling and the number input/output ports comparing with other network topologies. Sheer bulk of the wiring can be greater than the available space can accommodate. The hardware required to connect each link can be prohibitively expensive. Hybrid Topology A network can be hybrid, which uses two or more network topologies together in a network. An example of hybrid technology is the star ring network. OSI Model in the Network The OSI model was developed by the ISO (International Organization for Standardization) in 1947, as a model for a computer protocol architecture and as a frame work for developing protocol standards. The purpose of the OSI model is show how the communications are going through in a network between different systems. The OSI model is not a protocol; it is a model for understanding a network architecture .This model is flexible, very strong and interoperable. The OSI model is a layered frame work for the design of network systems that allows communication between all types of computer systems. OSI model contains of seven layers, each of which defines a part of the process moving information across a network. The OSI reference model has been divided into two categories according to their specific functions in the network architecture; upper layers and lower layers. The lower layers are used to allow traffic through the network to the other system. The other four layers are used to complete the process to the other system. The Advantages of the OSI model are given below It helps the user to understand the whole features involved in networking OSI model gives a better understanding to the users that how a software and hardware components working together in the networks. Troubleshooting in the OSI model is easier as it breaks the network into usable layers The basic functional relationship terms are defined so that it can be used by network professional on another network The users can understand new technologies as they develop in this model Upper Layers of the OSI Models are; Application layer Presentation layer Session layer The upper layers have act as an interface between the end user and the applications. It consists of all the issues about the application, presentation and sessions and these layers are applied in software only. The application layer is more close to the end user. Examples of upper layer technologies in the OSI model are SNMP, FTP, and WWW etc. Lower Layers of the OSI Model Transport Layer Network Layer Data link Layer Physical Layer These layers provide network specific functions like data transport issues (flow control, addressing and routing). The bottom layers in the OSI model (physical layer and data link layer) can use in software and hardware also. TCP, UDP, IP, IPX are some examples for the lower layers. Application layer The application layer act as the interface to the end users can access the network. Application layer is the layer the user sees in contest of loading an application such as e-mail, supporting the file transfer, ability to print on a network, surfing the World Wide Web etc. These layer have another specific functions like network virtual terminal, access and management, mail services and directory services. Protocols used in this layer are SMTP, Telnet, FTP, and SNMP. Presentation layer In the presentation layer, the application formats the data to be sent out on the network depending on the presentation layer. The presentation allows applications to read and understand the data or message sent.The presentation layer is also responsible for the translation, compression and encryption. Messages are sending between the layers. Presentation layer will translate data into understandable for the transmission. This layer also handles the encryption, decryption, data compression and decompression. Session layer The session layer is the network dialog controller. It establishes, maintains and synchronizes the interaction among communicating systems. This layer is responsible for opening, using and closing session. It handles the remote procedure calls. Session layers are communication through the gateways and application interfaces. Session layer will also places check points in the data flow. Examples for the session layer are SQL, ASP, and RPC etc. Transport layer The transport layer offers end to end communication between the two end networks devices in a network. The transport layer is also responsible for the delivery of a message from one process to another. A process is an application program running on a host. The transport layer ensures that the whole message arrives intact and in order, overseeing both error control and flow control at the source-to-destination level. Transport layer gives a type of address to the data called port address. Transport layer also have the responsibilities of detecting transmission error and the proper sequence. This layer divides the messages into smaller packets and it controls the data flow. Network layer A Network layer provides the end to end (source to destination) delivery of a packet, across the multiple networks (links). This layer ensures that each packet gets from its point of origin to its final destination. Network layer gives logical addressing, so that endpoint (receiver) can be identified. During a packet delivery process it send messages and report errors. This layer also defines the routing works and how routers can learn how a packet can deliver. Examples for network layer protocols are IP, IPX, and TCMP etc. Data link layer A Data link layer transforms the physical layer, a raw transmission facility, to a reliable link. It makes the physical layer appear error-free to the upper layer. This layer divides the datas into frames and gives the physical address. It uses the MAC address for define a hardware or data link address .Data link layer handles the flow control, error control and the access control. This layer can identify the specific computer on the network. Data link layer contains two sub layers; Logical Link Control and Medium Access Control. LLC is the upper layer and which maintain and establish the communication links to the device. And it also responsible for the frame error control and addressing.MAC is the lower sub layer of the data link layer. It controls how the devices sharing the media channel. Physical layer A Physical layer is used to define the connector and interface conditions, also the medium requirements which are cables. The Electrical, Mechanical, Procedural and Functional conditions are also defined by sending a bit stream on the network. This layer defines the characteristics and different types of medium. Physical layer defines the data rate i.e. the duration of a bit or how long they will exist. Physical layer will tell the transmission mode between two devices. Examples for the physical layers are Cables, hubs, switches, repeaters etc. Conclusion Network topologies helps the user to understand the whole features involved in networking and also how the software hardware components together in networks. Network topology provides easy to trouble shooting the OSI models. Users can understand very well about the new technologies in the OSI model. Resources I have searched various websites and books for gathering information about the network topologies and OSI model. Strength of the project I have studied the assignment very deeply and did very hard work for doing this assignment. I collected different type of resources for getting the information for this project like books, journals and websites etc. The project has been completed with the support of my lecture by giving some useful tips. Effective time scheduling really helps me for doing the project. Weaknesses of the project It was very hard to find out the important information for this assignment. Lack of experience for doing these kinds of assignment. What I learned from this project Project planning is very much important for doing a successful project. If we can spend relatively more time on our project, it will be much better for the project. I have learnt how to work under pressure and how to complete the given project in a scheduled time.

The Impact of the Tuberculosis Vaccine Essay -- Biology Medical Biomed

The Impact of the Tuberculosis Vaccine Abstract Tuberculosis is one of the most infectious diseases in the world. With almost one third of the world infected with this virus, people are striving to help prevent the spread of this disease (NIAID, 2001). One prevention technique for tuberculosis is the BCG (Bacillus of Calmette and Guerin) vaccine. In the early twentieth century Calmette and Guerin worked together to isolate a strain of the disease creating the first BCG vaccine. Throughout the century the scientists improved the BCG vaccine and today there are several different strains of the vaccine available. However, even today its full effects on the disease are unknown. The exploration of the effects of the vaccine, the best administration techniques, and who should be vaccinated continues. Throughout the Twentieth Century, Tuberculosis has impacted people around the world. While some countries see the impacts of tuberculosis less than others, the threat of this infectious disease looms across the horizon. Today, this organism affects one third of the population and is one of the most threatening of infectious diseases (NIAID, 2001). The BCG vaccine (Bacillus of Calmette and Guerin), is administrated in many high risk countries to combat the disease. Although scientists have improved the vaccine throughout the nineteenth century and the vaccine helps to combat some tuberculosis, its prevention is still far from perfect. The BCG vaccine is formed from a live strain of Mycobacterium bovis (WHO, 2005). The Mycobacterium bovis strain is taken from cows. It is a relative of Mycobacterium Tuberculosis, which affects humans; however, Mycobacterium bovis affects cows and humans alike. Isolating a strain of this living organism... ...h. 7/25/2005: http://www.pedresearch.org/cgi/content/full/55/2/347 2. Fine, P. and Carneiro I. et al. (1999, November). Issues relating the use of BCG in immunization programmes. World Health Organization. 7/19/2005: http://www.who.int/vaccines-documents/DocsPDF99/www9943.pdf 3. Ginsberg A. (2001, January). Tuberculosis Vaccine. National Institute of Allergy and Infectious Diseases. 7/19/2005: http://www.niaid.nih.gov/dmid/tuberculosis/tbvaccine.htm 4. Keep Kids Healthy. (2001, April). Tuberculosis in Children. Keep Kids Healthy. 7/21/2005: http://www.keepkidshealthy.com/welcome/infectionsguide/tuberculosis.html 5. WHO. (2005). BCG-the current vaccine for tuberculosis. World Health Organization. 7/25/2005: http://www.who.int/vaccine_research/diseases/tb/vaccine_development/bcg/en/print.html 6. Yancey, D. 2001. Tuberculosis. Brookfield: Twenty-First Century Books.

Sales and Inventory “Sheryn “

Chapter 1: Introduction I. INTRODUCTION In today's business environment, even small and mid-sized businesses have come to rely on computerized sales and inventory systems. Certainly, there are plenty of small retail outlets, manufacturers, and other businesses that continue to rely on manual means of inventory tracking. Indeed, for some small businesses, like convenience stores, shoe stores, or computer shops, purchase of an electronic inventory tracking system might constitute a wasteful use of financial resources.But for other firms operating in industries and features high volume turnover of raw materials and/or finished products, computerized tracking systems have emerged as a key component of business strategies aimed at increasing productivity and maintaining competitiveness. Moreover, the recent development of powerful computer programs capable of addressing a wide variety of record keeping needs—including inventory management—in one integrated system have also c ontributed to the growing popularity of electronic inventory control option.Computers began from a wild imaginative idea to the world’s highly prioritized tool. Computers today are now used as a substitute to manual processes and other past inventions like the radio, television, etc. It is now used by people for much simpler, easier and faster way to do things. Some used it as a hobby, and some use it as a job. 1. 1Background of the Study We the graduating students needs 1. 1. 1 History Memory Hub Computer is located on the 2nd floor of Lotus Mall, Nueno Ave.Imus city Cavite was a branch of the main shop located in the Robinson Mall. Its operation started back in 2007 who owned by a Chinese businessman who decided to invest his money in a right business opportunity like a desktop computer packages shop. Back then , in 2008 it become successful and the consumer demanded fore more. So the owner decided to expand its branch population here in the Cavite. 1. 1. 2 Mission and Visi on Why do we need a mission ? A Mission Statement defines the organization's purpose and primary objectives.Its prime function is internal – to define the key measure or measures of the organization's success – and its prime audience is the leadership team and stockholders. Why do we need a vision ? Organisations need to know where they are heading and what they are trying to accomplish and to state this clearly for getting there is dependent on the efforts of a large number of people – not all of whom can just be assumed to instinctively know what the collective goal is. An institution’s vision statement is thus an articulation of its major goals and ambitions.The organisation which does not articulate its vision for the future will not necessarily fail, indeed it may continue to ‘tick over’ quite nicely, but nor is it likely to thrive. It stands less chance of growing, expanding and improving because it has no clear idea of what direction o r form this growth, expansion or improvement should take. Not every good idea can be funded and not every opportunity pursued. Without a clear idea of where the institution is heading there is no sound basis for prioritising these decisions, resulting in an institution which is paddling as hard as it can, but making little real progress.Vision Statements also define the organizations purpose, but this time they do so in terms of the organization's values rather than bottom line measures (values are guiding beliefs about how things should be done. ) The vision statement communicates both the purpose and values of the organization. For employees, it gives direction about how they are expected to behave and inspires them to give their best. Shared with customers, it shapes customers' understanding of why they should work with the organization. 1. 1. 2. 1 MissionWe Memory Hub Computer wants to Give the best service and good quality to our valued costumers and make sure you will get best offer and best product. 1. 1. 2. 2 Vision Memoryhub Computer’s bring you a cheapest price but highly and good quality products. 1. 2 Statement of the Problem 1. 2. 1 General Statement of the Problem Based on our observation the manager is too busy in making a sales and inventory so we decided to make a program that can solved their problem no more hassle, time consumming and effortless and that program is a computerized sales and inventory by the used of computer the manager can do the task faster . . 2. 2 Specific Statement of the Problem Taking down sales and inventory manually it is a problem? Yes, because in our generation we have a lot of modern technology so that you can work faster and easier. So our group aim is to make a program that computerized by the used of computer you cannot write it in a paper , you can do your task less effort and time consuming. 1. 3 Objectives of the Study 1. 3. 1 General Objectives One of the problem in Memory Hub Computer is the manual s ales and inventory we decided to make a program that can solve their problem and that is Computerized Sales and Inventory. . 3. 2 Specific Objectives Having a computerized Sales and Inventory system they can filter, sort and searching data quickly by the used of computer rather than taking down ineventory mannually. 1. 4 Significance of the Study can create a system to support In the implementation of the enhanced computerized billing system, Cavite Landmark Marketing Incorporated and One Magnolia Place Realty’s will have a more secured business transaction. One Magnolia Place Realty employees will benefit this study in everyday transactions pertaining to their tenants billing payment and information.The importance of this study is to make a comparison between the current the project that was given by ourinstitution,Datacom Institute of Computer Technology. 1. 5 Scope and Limitation Scope means the extent of your investigation. Limitations are the limits or things you did not investigate, or the reasons why your conclusions may not be valid. The â€Å"scope† section is where you list what you are doing. The â€Å"bounds† section is where you set the boundaries and you list some thing explicitly that you are not doing because they are outside the bounds of the project.At first, having two sections sounds redundant, but it removes ambiguity. Try to imagine questions and head them off. You might know what you mean by â€Å"high school† but some people reading your work may have different interpretations. Don't assume too much about your readers. Limitations are the circumstances which are not considered in the thesis because of some reasons like if a student interprets the relation between inflation and interest rates then the limitation can be the 100% accuracy of data.Moreover, all the situations which can limit the interpretation of data are considered the limitations. It is very important to describe the limitations in thesis, so t hat the reader may know about the circumstances in which the researcher has conducted the thesis. . 1. 5. 1 Scopes The proposed system of Memory Hub Computer is designed to have an ability of filtering,sorting,searching, storing and saving data. It can access by the used of username and password but it has a limitation.You can make your inventory faster by the used of computer. You can do other task fast. You can consume your time wise. 1. 5. 2 Limitations All programs has a limitations , so our system design has an ability of serching , storing and saving but it has a limitation like you cannot edit data without the permission of manager because it has a username and password. Another one is you cannot put the number of stocks, the stocks that left, and so on without computer because it is computerized.

Violence and Societal Change in Beowulf Essay - 1305 Words

It is said that up to thirty thousand men may have died at the battle of Hastings, a conflict that occurred almost one thousand years ago. World War II, which lasted less than seven years, has been estimated to be responsible for up to forty million deaths. Thus, many people often ask the question why? Why does such conflict occur? Who or what is responsible? The culprit does not hide nor has it escaped scrutiny and blame. It comes in many shapes and sizes, faces and places. It is called violence and the potential for it resides in every single person on this earth. Whose violence conquers all? It is hard to measure the significance of violence, especially when it can cause so much destruction and death as well as stimulation. However,†¦show more content†¦It is through these acts of violence that societal change is achieved and order restored. â€Å"†¦History is a continuous clash between conflicting ideas and forces†. That’s how the fifth Canadian edition of â€Å"Sociology In our Times† summarizes Karl Marx’s ideologies on conflict and change and that is the premise of Beowulf. The history of the Danish society is described during the prologue of the story and is immediately tied into violence and can clearly be identified with this passage, â€Å"Beow’s name was known through the north†¦afterward in age when fighting starts/ steadfast companions will stand by him/ and hold the line† (Beowulf 34, 19-24). The author admittedly points out right after this that â€Å"Behaviour that’s admired/ is the path to power among people everywhere† (34, 24-25). It is evident then that violence in Beowulf is a behaviour that should be associated and recognized by admiration. Furthermore, it is apparent that fighting and conflict form the foundations of the society that B eowulf lives in through this passage â€Å"The fortunes of war favored Hrothgar./ Friends and kinsmen flocked to his ranks,/ young followers, a force that grew/ to be a mighty army†. (Beowulf 35, 64-67) Hence, before Beowulf is even introduced to the poem it is understood that violence is central to the functioning of the society. The very presence of Beowulf in Beowulf arises from the need for change. This change is brought about by violence and isShow MoreRelatedThe Importance Of Female Heroism Through The Epic Of Beowulf1660 Words   |  7 PagesBeowulf is known for displaying the importance of male heroism via Beowulf, but what about the significance of the women in the poem? The significance of women in Beowulf is overshadowed by the great heroism of the character Beowulf, but the women each have a reason for participating in the epic. The ideal woman was someone who was a noble, a mistress and loyal. An ideal woman is described in Maxim I: â€Å"at mead drinking she must at all times and places approach the protector of princes first, in front