LM01-CSCC0323-CP03-1

Introduction

  • The course discusses signaling techniques used on modern networks.

  • Covers coaxial cable, twisted pair cable, and fiber-optic cable.

  • Describes the physical media characteristics: cost, materials, and connector types.

Pre-Assessment

  • Differentiate various transmission media by:

    • Costs

    • Throughput

    • Noise immunity

    • Size and scalability

Transmission Basics

  • Transmit: Issuing signals along a network medium (e.g., cable).

  • NICs (Network Interface Cards) can transmit and receive signals (are transceivers).

Analog and Digital Signaling

  • Signaling types in data networks:

    • Analog: Generated as variable voltage (continuous waves).

    • Digital: Signals as discrete pulses measured in volts.

Analog Signal Properties

  • Characterized by four basic properties:

    • Amplitude: Height of the wave (strength).

    • Frequency: Cycles of amplitude over time.

    • Wavelength: Distance between peaks.

    • Phase: Progress of the wave over time.

Key Points

  • Information transmission methods: Analog and Digital.

Definitions

  • Analog: Continuous variable voltage signal, less accurate.

  • Digital: Composed of discrete pulses (0 or 1).

  • Volt: Measurement of electric current pressure on a conductor.

  • Voltage: Intensity of electric current.

Benefits and Drawbacks of Signals

  • Analog Signal: More variable and conveys subtleties with less energy, but is imprecise and prone to flaws.

  • Digital Signal: More reliable, less affected by noise, requires more pulses (overhead).

Overhead Definition

  • Non-data information needed for signal routing/interpretation (e.g., network addressing).

Data Modulation

  • Essential for transmitting between digital and analog systems (modulation/demodulation).

  • Modem: Device that modulates and demodulates signals.

Modulation Techniques

  • Frequency Modulation (FM): Alters the carrier frequency with data.

  • Amplitude Modulation (AM): Alters carrier amplitude with data.

Transmission Categories

  • Simplex: One-way communication.

  • Half-Duplex: Both ways, but one at a time.

  • Full-Duplex: Both ways simultaneously (e.g., Ethernet).

Multiplexing

  • Allows multiple signals over one medium.

  • Multiplexer (mux): Combines channels at transmission.

  • Demultiplexer (demux): Separates signals at receiving end.

Types of Multiplexing

  • Time Division Multiplexing (TDM): Divides channel into time slots.

  • Statistical Multiplexing: Assigns slots based on priority (more efficient).

  • Frequency Division Multiplexing (FDM): Assigns unique frequency bands.

Wavelength Division Multiplexing (WDM)

  • Used in fiber-optic connections to carry multiple signals.

  • DWDM: Can carry 80-160 channels, used in high-bandwidth WAN links.

Relationships Between Nodes

  • Point-to-Point: One transmitter to one receiver.

  • Point-to-Multipoint: One transmitter to multiple receivers (broadcast and non-broadcast).

Broadcasting Example

  • Radio stations disseminate signals to multiple antennas.

Throughput and Bandwidth

  • Throughput: Data transmitted over a period.

  • Bandwidth: Difference between highest/lowest frequencies medium can transmit.

Baseband vs. Broadband

  • Baseband: Digital signals; one signal/channel at a time (e.g., Ethernet).

  • Broadband: Radio frequency signals; multiple signals simultaneously (e.g., cable TV).

Transmission Flaws

  • Analog and digital signals are susceptible to:

    • Noise: Distorts signals (e.g., EMI and cross talk).

Noise Types

  • EMI: From electrical devices or cables.

  • Cross Talk: Signal interference from adjacent wires.

Other Transmission Flaws

  • Attenuation: Signal strength loss over distance. Signals can be boosted using amplifiers (analog) or repeaters (digital).

  • Latency: Delay in signal transmission; measured as round trip time (RTT).

Common Media Characteristics

  • Match networking needs with media characteristics:

    • Throughput: Limited by physics and technology.

    • Cost: Variable based on installation, infrastructure, maintenance.

    • Noise Immunity: Fiber-optic cables least susceptible to noise.

    • Size and Scalability: Maximum nodes and segment lengths depend on latency and attenuation.

Connectors and Media Converters

  • Specific for particular media types, affect installation and maintenance cost.

  • Media converters enable networks on different media to interconnect.

Coaxial Cable

  • Consists of a central metal core with insulation and shielding.

  • Higher noise resistance; suitable for longer distances than twisted pair cable.

Coaxial Specifications

  • RG-6: 75 ohms; used in cable TV.

  • RG-8: 80 ohms; used in Thick Ethernet.

  • RG-58: 50 ohms; used in Thin Ethernet.

  • RG-59: 75 ohms; used for video distribution.

Connectors for Coaxial Cables

  • F-type and BNC connectors used to terminate coaxial cables.

Twisted Pair Cable

  • Composed of color-coded insulated pairs of copper wire.

Properties of Twisted Pair Cabling

  • More twists reduce cross talk; categorized into various types (e.g., CAT 3, CAT 5, CAT 6).

  • STP: Shielded against electromagnetic interference.

  • UTP: Less expensive, less noise resistance.

Fiber-Optic Cable

  • Composed of glass/plastic fibers transmitting data as light pulses.

Characteristics of Fiber-Optic Cables

  • Higher throughput, high noise resistance, longer distances, though more expensive.

  • Single-Mode Fiber (SMF): Narrow core for long-distance transmission.

  • Multimode Fiber (MMF): Larger core for shorter distances but with higher attenuation.

Fiber-Optic Converters

  • Connect multimode and single-mode fiber networks.

Serial Cables

  • Uses sequential data transmission.

  • RS-232: Defines several connector standards.

References

  • Dean, T. (n.d.). Network+ Guide to Networks (6th ed.). Course Technology, Cengage Learning.

Post-Assessment

  • Differentiate transmission media by costs, throughput, noise immunity, size, and scalability.