a) Explain the working principles of the data link layer. 2
b) Is controlled access better than contention for media access control? Discuss. 2
c) Why is error detection important in this layer? What is being measured? 3
d) Identify three significant noises that can cause errors in data communication digital circuits. Briefly explain. 3
Part 2: General review of error correction 4
a) Why is cyclical redundancy check (CRC) most popular error checking scheme? 4
b) How is Hamming distance used in error correction? Explain. 4
c) Briefly explain how parity is used to find the location of single-bit errors in the forward error correction…show more content… Briefly explain.
Line noise and distortion can cause data communication errors. Errors can occur during data transmission. Data transmitted both analogue and digital is susceptible to many types of noise and errors. The three significant noises that can cause error in data communication digital circuits are:
White noise: white noise also called thermal noise or Gaussian noise. This noise is a relatively continuous type of noise and much like the static you hear on radio between two stations. It will always be present in some degree of transmission media and electronic device and is also dependent on the temperature of the medium. The level of noise increases due to the increased movement of electrons in the medium. The white noise can be removed from the digital signal by passing the signal through a signal regenerator before the noise completely overwhelms the original signal (White 2007).
Impulse noise: Impulse noise or also called noise spike is a noncontinuous noise and the most difficult errors to detect since it occurs randomly. Difficulty comes in separating the noise from the signal. Some of the sources of impulse noise are voltage change, lightning flashes during thunderstorms, fluorescent lights and poor connection in circuits. If the impulse noise interferes with the digital signal, often the original digital signal can be recognized and recovered. The way to prevent impulse noise is by shielding or moving cables (White
understand it to a degree. I know the OSI has seven layers and that it represents communication between two computers on a network. I can list the seven layers; they are the application layer, the presentation layer, the session layer, the transport layer, the data link layer and the physical layer. I know these layers work together to transfer data from one computer to another. The layers to me get confusing and I keep trying but know that without all layers the OSI would not work correctly. Now I want…
| |Physical layer |Transmits bits throughout the network’s |Changes data packets to physical signals | | |physical medium. Performs services |which symbolize 1’s and 0’s and later sends| | |requested by the data link layer. |physical signal to the destination | |Data link layer |The Data link layer is in charge of…
The OSI model has seven layers (see Figure 1.3). Layer 1: Physical Layer The physical layer is concerned primarily with transmitting data bits (zeros or ones) over a communication circuit. This layer defines the rules by which ones and zeros are transmitted, such as voltages of electricity, number of bits sent per second, and the physical format of the cables and connectors used. Layer 2: Data Link Layer The data link layer manages the physical transmission circuit in layer 1 and transforms it into…
a server? Question options: stores data and software that can be accessed by client devices. is the pathway through which messages travel. in client/server computing, servers together over the network with client computers to support business applications. can only perform one function on a network. stores documents and graphics that can be accessed from a Web browser. Question 2 1 / 1 point Networks designed to connect similar computers that share data and software with each other are _________…
Physical layer Encompasses details such as electrical and mechanical connections to the network, transmission of binary data as changing voltage levels on wires or similar concepts on other connectors and data raters. Data link layer The Open Systems Interconnection (OSI) layer (2) that is responsible for data transfer across a single physical connection (or series of bridged connections, between two Network entities). The data link layer detects and may correct errors in the physical layer. Network…
Two TCP/IP data-link protocols are Ethernet and PPP. Data-link protocols define addresses that identify devices connected to the underlying physical link. 19. Which of the following answers lists true facts about the transport layer of ICP/IP? None of the answers are correct. 20. A PC user opens a web browser and sends a request to a web server to load a new web page. Three routers forward the data as it passes from client to server. Consider the data plus all headers and trailers…
Physical, Data, Link, Network, Transport, Session, and Presentation Exercise 3.1.4 If the model is too general, then you would not be able to completely understand it. If it were too granular, you still would not be able to understand it. Exercise 3.2.1 7 Application The way we see or input data. 6 Presentation Data is returned or input into the devices. 5 Session Communication to the network is opened. 4 Transport Network is sending or receiving data. 3 Network Where the data is. 2 Data Link Opens the…
When comparing frame relay with ATM, (asynchronous transfer mode), as a layer 2 protocol you are comparing packets with cells and two technologies that will both be obsolete soon. In regards to frame relay, it is a slower, more careful, error-correcting X.25 packet based technology. Frame Relay differs from X.25 in several ways though. It is a much simpler protocol that works at the data link layer rather than the network layer. It implements no error or flow control and its simplified handling of…
including voice, data, and video signals".[1] ATM was developed to meet the needs of the Broadband Integrated Services Digital Network, as defined in the late 1980s,[2] and designed to unify telecommunication and computer networks. It was designed for a network that must handle both traditional high-throughput data traffic (e.g., file transfers), and real-time, low-latency content such as voice and video. The reference model for ATM approximately maps to the three lowest layers of the ISO-OSI reference…
