The Media Access Control System Essay

2: Data Link Layer: It take care of errors in physical layer. The main aim of the data link layer is to controls the flow of frame synchronization and transmission protocol. The data link layer divided in to two types. They are Media Access Control (MAC) and Logical Link Control (LLC).

Layer 5: Session - Layer 5 establishes, maintains and ends communication with the receiving device.

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

• “Application - The Application Layer is the layer that most network users are exposed to, and is the level at which human communication happens. HTTP, FTP, and SMTP are examples of the application layer protocols the Patton-Fuller will now be utilizing for communicating electronically” (Network Design, 2012).

It is operating on best effort delivery model, i.e. it does not guarantee delivery, nor does it assure proper sequencing or avoidance of duplicate delivery. These aspects, including data integrity, are addressed by an upper layer transport protocol, such as the Transmission

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).

Layer 4 is the transport layer and utilises common transport protocols to enable network communications. This may include the Transport Control Protocol (TCP) and Universal Data Protocol

The internet layer is built up of four core protocols: IP, IGMP, ICMP and ARP. Internet protocol (IP) is responsible for routing, IP addressing and breakdown/reassembly of data packets, address resolution protocol (ARP) is responsible for mapping an IP address to a device on the local network, internet control message protocol (ICMP) provides diagnostic information and error reports on lost packets, internet group management protocol (IGMP) controls who receives IP datagrams in a single transmission. The transport layer is built up of two core protocols: TCP and UDP. Transmission control protocol (TCP) sequences and acknowledges packets sent and their recovery when lost in transmission allowing the computer to make and maintain network conversations where applications exchange data, defined as a connection-oriented protocol meaning the connection is maintained until the programs has finished exchanging data. User datagram protocol (UDP) This is used to transfer small amounts of data when the use of error correction isn’t needed increasing the speed of the transmission, common in multi-player video games as the user will not need to receive packets of past events in the game so the error correction featured in (TCP) would be

1. How does the abstraction of the physical layer facilitate interoperability across networks using different types of physical wires?

The layer starts from 7 being the top layer and 1 being the lowest layer of the OSI model. Application layer- Serves as the window for users and application processes to access networks services like web browser (Internet explorer, Mozilla) protocols – DNS & SSH etc. Presentation layer- Translates data from the format send into the format that program can understand. Session Layer- Starts and end session and also keeps them isolated protocols- SMB,NFS, Socks and allows session establishment between processes running on different stations. Network- Determines addressing method for being transmitted. Transport- Defines ports and reliability protocols- TCP, UDP. Network- logical or IP addressing: Determines best path for the destination protocols- IPV4, IPV6, ICMP, IPsec. Data link- Contain data into a frame that contains a header with a destination. Switches, Mac addressing protocols- PPTP, Token Ring. Physical Link- Determines the hardware used and the method used for data transmission like cables, network interface cards, electrical

1. R3. What are some of the possible services that a link-layer protocol can offer to the network layer? Which of these link-layer services have corresponding services in IP? In TCP?

Each layer has a specific function and the layers work together to allow an application to send data over a computer network without really specifying the exact protocols and/or physical wiring within each layer. In line with the figure above, when the first CEO sends an email message to the second CEO, email ‘application worker’ firstly prompts the first CEO to enter a message and specify that the receiver is the second CEO. The application worker then creates the necessary data package with message contents and the destination email address and send s this to a ‘transport worker’. The transport worker provides transport integrity. The transport worker may establish a connection with the receiver (second CEO); monitor the overall

The application layer: this layer allows different applications to communicate with each other’s. In order to exchange different data over the network connection, the protocols included in this layer set up the standards such as DNS, HTTP, FTP. The data coded in this layer will be encapsulated to transport layer for further packing.

Transmission Path Level: This extends between network elements that assemble and disassemble the payload of a transmission system. For end-to-end communication, the payload is end-user information. For user-to-network communication, the payload may be call-control signaling information (call setup and call termination). Cell delineation and header error-control functions are required at the end points of each transmission path.