DATA AND COMPUTER COMMUNICATIONS

The third layer is the one where the Yanomamo live in, which they say was created when a piece of the second layer fell off. The bottom most layer, the Yanomamo say, was created when the sky fell to earth on top of a particular settlement, and pushed it down through to the underside; the people of the settlement were forced to eat each other. The belief that souls are regularly carried off to be eaten below reflects the Yanomamo’s fear of cannibalism.

1: Physical layer: The purpose of the physical layer is it deals with the hardware components, like cads and cables for sending and receiving data of a carrier.

Layer 4: Transport - This layer maintains flow control of data and provides for error checking and recovery of data between the devices.

The fifth layer is the session layer this establishes a connection,this layer makes and sets up the connection using co ordinates and could terminate conversations links. the session layer produces services that make authentication after an interruption and not only that but it can reconnect.and as well as the transporting layer it can also have the TCP and the UDP can provide services for all most all applications.An application layer is an abstraction layer that specifies the shared protocols and interface methods used by hosts in a communications network. The application layer abstraction is used in both of the standard models of computer networking; the Internet Protocol Suite (TCP/IP) and the Open Systems Interconnection model (OSI model).Although both models use the same term for their respective highest level layer, the detailed definitions and purposes are different.In TCP/IP, the application layer contains the communications protocols and interface methods used in process-to-process communications

1. Application (in terms of cabling infrastructure): The application layer is the OSI layer closest to the end user, which means both the OSI application layer and the user interact directly with the software application. When determining resource availability, the application layer must decide whether sufficient network or the requested communication exists.. (OSI_model#Layer_7:_application_layer)

The OSI (Open System Interconnection) model is a set of specifications that allow computers around the world to openly communicate. It is pivotal to understanding and developing computer to computer communications in a network. Each layer plays a role in the process of sending and receiving data. The application layer is the top layer (layer seven) it promotes communication between programs and lower-layer network services. The services at this layer allow the network to decipher a program's request and the program to decipher data sent from the network. The Application layer protocols, programs handles formatting, procedure, security, synchronization, and any other requirements with the network. The Presentation Layer (layer 6) acts as a translator. For instance these protocols decode the jpg/jpeg files sent within the Web server’s HTTP response. So, in the last step (the Application layer) we enter the Web address and it took us to the Web site. This step allows us to see the images and content of the site. The Session Layer (layer 5) regulates and controls the communication between two nodes on the network. It is an ongoing exchange of data between the two and keeps the connection between them for the duration. It keeps the communication secure, detects whether or not the communication has been cut off and if it has it determines where to restart the

In the seven layers of the OSI, control is passed between layers. The model is theoretical, but tells us how a network takes the data sent from the application all the way down to the physical layer and out, to in the physical layer and back up all the way to the application layer. This Model has nothing to do with the actual functions of the process. Instead it is a concept of the framework, so the complexities of a network can be broken down and understood (Beal, 1999).

The Application layer within the OSI reference model is where the application and the user communicates. In other words, the application layer is the ending of data that is transferred in visual form to the user. This layer provides the interface between the applications we use to communicate and the underlying network over which our messages are transmitted. The Application Layer functions are to provide the interface for application-specific protocols commonly used such as HyperText Transfer (HTTP), file transfer (FTP), Simple mail transfer (SMTP), Internet message Access (IMAP),

The first three layers of the OSI is typically what a router needs to route traffic. The first three layer are physical, data link and network. The highest level the OSI decide where to forward traffic to is the transport layer which is located in the host layers.

2. DATA LINK (Layer2) – divided into 2 sub layers: MAC, which controls how a computer on the network gains access to the data and permission to transmit it, and LLC which controls frame synchronization. At this layer, data packets are encoded and decoded into bits. It furnishes transmission protocol knowledge and management and handles errors in the physical layer, flow control and frame synchronization.

- The third step: You need to establish a list of your employees on the system. You need to fill in employee’s name, address of employees, tax information such as Tax File Number (TFN) and etc.

The transport layer: This layer determines how the packets are transported such as the order and what to do if there are errors. The purpose of this layer is to make sure the data be transported correctly. Besides, due to the limitation of physic (maximum IP packet size is 65535bits), the speed of transportation is limited. As a result, this layer needs break big data in to small packets. This can also collect small data into a big packet to reduce unnecessary transmission, which can improve the transmitting speed. Example protocols are TCP, UDP, SCTP.

As the data packet moves from the upper to the lower layers, headers are _______.

The ability to send and receive data efficiently is the most important objective of networking computers.

Advancements in the information technology sector have brought many benefits to the people all around the world.  Today with computer networking, we can chat, speak and see each other over a long distance. Data communication refers to the transmission of the digital signals over a communication channel between the transmitter and receiver computers. Communication is possible only with wired and wireless connectivity of the computers with each other.