1 CSC 322 Review A slide to a chapter summary of the material covered (based on the 8/e book)

2 C1. Data Communications and Networking Overview The 3 (or 5) entity general communication model Actual data communications is more complicated –Transmission system utilization, interface, signal generation, synchronization, exchange management, error detection and correction, flow control, addressing, routing, recovery, message formatting, security, network management Networking –LANs (one organisation, smaller area, faster speeds) –WANs (larger areas, crossing public rights of way, common carrier circuits) circuit switching, packet switching –frame relay, cell relay (ATM) –MANs (middle ground)

3 C2. Protocol Architecture A simple (quite general) protocol architecture –Protocols: syntax, timing, semantics Layering combats complexity –Peer layered architecture –Information flow (down  across  up) Open System Interconnection (OSI) –7 layers –Standardisation framework –Service Primitives, and Parameters The TCP/IP protocol architecture –5 layers –The “industry/world” standard

4 C3. Data transmission Terminology –Frequency, spectrum, bandwidth, effective bandwidth, etc Any signal can be expressed as an infinite number of sine waves (frequency components). –Remember it is only the odd ones (f, 3f, 5f, 7f….) Relationship between data rate and bandwidth –The higher the data rate the higher the required bandwidth –The higher the bandwidth the greater data rate can be achieved Transmission impairments –attenuation, delay distortion, noise (4 types) Channel capacity –Nyquist (error & noise free, f(B, channels)) –Shannon (error free, f(B, SNR))

5 C4. Transmission Media Guided media –Twisted pair (2 versions), coaxial, optical fibre –Description, characteristics, categories Wireless transmission technologies –Dish antenna, Antenna gain –Microwave (earth & satellite), broadcast radio, infrared Wireless propagation –Skywave, line-of-sight, groundwave Wireless (line-of-sight) impairments –Free space loss, refraction, atmospheric absorption, mutlipath

6 C5. Signal Encoding Techniques Digital(=D) & Analogue(=A) Data –to Digital & Analogue Signals D-data  A-signal –Frequency/Phase/Amplitude shift keying D-data  D-signal –NRZ, Multilevel, Biphase –Scrambling A-data  D-signal –Delta, Pulse code A-data  A-signal(3) –AM, FM

7 C6. Digital Data Communication Techniques Transmission approaches –Synchronous –Asynchronous Errors, types –Single bit, Burst errors Error detection –Check bits Error correction –FEC, Redudancy, hamming distance

8 C7. Data Link Control Protocols Flow control (S&W, SW) Error control –4 Mechanisms of ARQ –3 version of ARQ HDLC protocol –Basics types of stations (3) Configuration (2) modes (3) –Frame types and structure (I / S / U) –Operation (3 phase type)

9 C8. Multiplexing Utilising a single line to relay multiple connections Frequency Division MUXing Time Division MUXing –MUXed line has at least the data rate of the sum of lines –Slots are fixed and allocated Statistical Time Division (relies on non frequent use) –Slots are allocated on demand –MUXed line has less than the sum of lines being MUXed ADSL –Separates the 1MHz in 3 regions (POTS, Upstream, Downstream) –FDM within upload and download

10 C14. Cellular Wireless Networks Not covered fully (first 14 slides) Cellular network organisation –Cells –Frequency reuse –Increasing the capacity Operation of a cellular systems –Base station –Cells –MTSO

11 C17. Wireless Networks Single and multi cell LANs Applications (nomadic, adhoc, cross building, lan extension) Technologies (just the names) –IR, Spread spectrum, Narrow band microwave

12 C15. LAN Overview LAN applications (high speed, backbone, storage area networks, personal, backend) Topologies (ring, star, bus, tree) IEEE 802 reference model –LLC and MAC Medium Acces Control –Central vs distributed –Synchronous vs asynchronous Asynhronous –Round robin, reservation, contention Bridges, Switches, Hub, Layer 2 & 3 (hardware switches)