Physical Layer Characteristics
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Questions and Answers

What is the primary purpose of encoding in the physical layer?

  • To generate electrical signals that represent the 1s and 0s on the media
  • To provide a wireless signal that can be recognized by both the sender and receiver
  • To define the type of signal that represents a 1 and a 0
  • To convert the stream of bits into a recognizable format by the next device in the network path (correct)

    • What does Manchester encoding represent as a 0 bit?

  • A constant low voltage
  • A low- to high-voltage transition
  • A constant high voltage
  • A high- to low-voltage transition (correct)

    • What is the name of the encoding method used in Ethernet 100BASE-T?

  • 8B/10B encoding
  • 4B/5B encoding (correct)
  • 10B/8B encoding
  • Manchester encoding

    • What is the primary function of the physical layer in terms of signaling?

    <p>To generate the electrical, optical, or wireless signals that represent the 1s and 0s on the media</p> Signup and view all the answers

    What is the purpose of defining the type of signal that represents a 1 and a 0 in the physical layer?

    <p>To enable devices to recognize the binary data</p> Signup and view all the answers

    What is the name of the encoding method used in older Ethernet standards, such as 10BASE-T?

    <p>Manchester encoding</p> Signup and view all the answers

    What occurs at the middle of each bit period in Manchester encoding?

    <p>A voltage transition from high to low and low to high</p> Signup and view all the answers

    What is the method of signaling dependent on in the physical layer?

    <p>The type of medium being used</p> Signup and view all the answers

    What is the primary function of the physical layer in the OSI model?

    <p>To encode frames and create signals for transmission</p> Signup and view all the answers

    Who defines the protocols and operations of the upper OSI layers?

    <p>Software engineers and computer scientists</p> Signup and view all the answers

    What is the primary focus of the Physical Layer Standards?

    <p>Specifying the hardware components and connectors</p> Signup and view all the answers

    What is the role of the destination node's physical layer in the OSI model?

    <p>To retrieve individual signals from the media and restore them to their bit representations</p> Signup and view all the answers

    What is the primary function of the encoding functional area in the Physical Layer Standards?

    <p>To convert bits into signals for transmission</p> Signup and view all the answers

    What type of organizations define the standards governing the physical layer?

    <p>Electrical and communications engineering organizations</p> Signup and view all the answers

    What is the role of the physical layer in the transmission process?

    <p>To transmit signals over the physical medium</p> Signup and view all the answers

    What is included in the Physical Components functional area of the Physical Layer Standards?

    <p>Hardware devices, media, and connectors</p> Signup and view all the answers

    What is the primary factor that determines the practical bandwidth of a network?

    <p>The properties of the physical media</p> Signup and view all the answers

    What is the unit of measurement for digital bandwidth?

    <p>Bits per second</p> Signup and view all the answers

    What is latency in the context of bandwidth?

    <p>The time it takes for data to travel from sender to receiver</p> Signup and view all the answers

    What is the equivalent of 1,000,000,000 bps?

    <p>1 Gbps</p> Signup and view all the answers

    What is the primary characteristic of the physical layer of a network?

    <p>Bandwidth and latency</p> Signup and view all the answers

    What is the term used to describe the amount of data that can flow from one place to another in a given amount of time?

    <p>Digital bandwidth</p> Signup and view all the answers

    What is the relationship between the properties of physical media and available bandwidth?

    <p>The properties of physical media determine the available bandwidth</p> Signup and view all the answers

    What is the term used to describe the actual amount of useful data transferred?

    <p>Goodput</p> Signup and view all the answers

    What is the primary factor that affects the amount of time data takes to travel from one point to another?

    <p>All of the above</p> Signup and view all the answers

    What is the definition of throughput in the context of computer networks?

    <p>The measure of the transfer of bits across the media over a given period</p> Signup and view all the answers

    What is the relationship between goodput and throughput?

    <p>Goodput is always lower than throughput</p> Signup and view all the answers

    Why is copper cabling limited by distance?

    <p>Due to attenuation</p> Signup and view all the answers

    What is the primary cause of crosstalk in copper cabling?

    <p>Electric or magnetic fields of adjacent signals</p> Signup and view all the answers

    How can attenuation be mitigated in copper cabling?

    <p>By adhering to cable length limits</p> Signup and view all the answers

    What is the advantage of using copper cabling in networks?

    <p>It is inexpensive and easy to install</p> Signup and view all the answers

    What is the primary difference between throughput and goodput?

    <p>Throughput measures total data, while goodput measures usable data</p> Signup and view all the answers

    What is a key advantage of fiberoptic cables over other types of cabling?

    <p>Immunity to EMI and RFI</p> Signup and view all the answers

    What is the primary benefit of using wireless media?

    <p>Greatest mobility</p> Signup and view all the answers

    What is a limitation of wireless media in terms of coverage?

    <p>It is affected by physical barriers</p> Signup and view all the answers

    Why is wireless communication vulnerable to security threats?

    <p>It requires no access to a physical strand of media</p> Signup and view all the answers

    What is a characteristic of WLANs?

    <p>They operate in half-duplex</p> Signup and view all the answers

    What happens when many users access a WLAN simultaneously?

    <p>The bandwidth for each user is reduced</p> Signup and view all the answers

    What is the bandwidth range supported by fiber-optic cabling?

    <p>10 Mb/s - 100 Gb/s</p> Signup and view all the answers

    What is the primary standard for wireless data communications?

    <p>IEEE</p> Signup and view all the answers

    Study Notes

    Physical Layer Characteristics

    • Encoding converts a stream of bits into a recognizable format for the next device in the network path using predefined codes that provide a predictable pattern.
    • Examples of encoding methods include Manchester encoding, 4B/5B encoding, and 8B/10B encoding.

    Physical Layer Characteristics: Signaling

    • The physical layer generates electrical, optical, or wireless signals that represent the 1s and 0s on the media.
    • The signaling method represents the bit values "1" and "0" on the physical medium.
    • The method of signaling varies based on the type of medium being used.

    Physical Layer Characteristics: Physical Layer Standards

    • The physical layer consists of electronic circuitry, media, and connectors developed by engineers.
    • The standards governing this hardware are defined by the relevant electrical and communications engineering organizations.
    • Physical Layer Standards address three functional areas: Physical Components, Encoding, and Signaling.

    Physical Layer Characteristics: Physical Components

    • Physical Components are the hardware devices, media, and other connectors that transmit the signals that represent the bits.
    • Examples include NICs, interfaces, connectors, cable materials, and cable designs.

    Physical Layer Characteristics: Bandwidth

    • Bandwidth is the capacity at which a medium can carry data, measuring the amount of data that can flow from one place to another in a given amount of time.
    • Factors determining the practical bandwidth of a network include the properties of the physical media, technologies chosen for signaling and detecting network signals, and the laws of physics.
    • Units of bandwidth include bits per second (bps), kilobits per second (Kbps), megabits per second (Mbps), gigabits per second (Gbps), and terabits per second (Tbps).

    Physical Layer Characteristics: Bandwidth Terminology

    • Latency is the amount of time, including delays, for data to travel from one given point to another.
    • Throughput is the measure of the transfer of bits across the media over a given period of time.
    • Goodput is the measure of usable data transferred over a given period of time, taking into account traffic overhead.

    Copper Cabling: Characteristics of Copper Cabling

    • Copper cabling is the most common type of cabling used in networks today, characterized by low cost, ease of installation, and low resistance to electrical current flow.
    • Limitations of copper cabling include attenuation, susceptibility to electromagnetic interference (EMI) and radio frequency interference (RFI), and crosstalk.

    Wireless Media: Properties of Wireless Media

    • Wireless media carries electromagnetic signals representing binary digits using radio or microwave frequencies, providing the greatest mobility option.
    • Limitations of wireless media include coverage area, interference, security risks, and shared medium.

    Wireless Media: Types of Wireless Media

    • The IEEE and telecommunications industry standards for wireless data communications cover both the data link and physical layers.

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    Related Documents

    Lec06_physical layer.pptx

    Description

    Learn about the physical layer's role in encoding and transmitting data in computer networks. Understand how it converts digital bits into electrical, optical, or radio wave signals and retrieves them at the destination node.

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