COE 342: Data & Computer Communications (T042) Dr. Marwan Abu-Amara Chapter 1: Data Communications & Networking Overview

COE 342 (T042) – Dr. Marwan Abu-Amara Course Outline Data Communications & Networking Overview (Ch. 1) Protocol Architecture (Ch. 2) Data Transmission (Ch. 3) Guided and Wireless Transmission (Ch. 4) Signal Encoding Techniques (Ch. 5) Digital Data Communication Techniques (Ch. 6) Data Link Control (Ch. 7) Multiplexing (Ch. 8) COE 342 (T042) – Dr. Marwan Abu-Amara

COE 342 (T042) – Dr. Marwan Abu-Amara Agenda Introduction Communications Model Main blocks and functionality Communication Tasks Data Communications Data Communication Networking Wide Area Networks Circuit switching Packet switching Frame Relay ATM Local Area Networks COE 342 (T042) – Dr. Marwan Abu-Amara

COE 342 (T042) – Dr. Marwan Abu-Amara Introduction Fundamental purpose of communications system is exchange of data between 2 parties 3 general areas: Data Communications Transmission of signals in reliable & efficient manner Covers signal transmission, transmission media, signal encoding, interfacing, data link control, multiplexing Networking Covers technology & architecture of communication networks Divided into LANs & WANs Protocols COE 342 (T042) – Dr. Marwan Abu-Amara

Simplified Communications Model - Diagram COE 342 (T042) – Dr. Marwan Abu-Amara

A Communications Model Source Generates data to be transmitted Transmitter Converts data into transmittable signals (modulation, encoding, …) Transmission System Carries data Receiver Converts received signal into data (opposite to “Transmitter” role) Destination Takes incoming data COE 342 (T042) – Dr. Marwan Abu-Amara

COE 342 (T042) – Dr. Marwan Abu-Amara Communications Tasks Transmission system utilization Addressing Interfacing Routing Signal generation Recovery Synchronization Message formatting Exchange management Security Error detection and correction Network management Flow control COE 342 (T042) – Dr. Marwan Abu-Amara

Simplified Data Communications Model May involve buffering and/or encoding of digital data (Ch. 5) Modulated signal, s(t), matched to media (Ch. 3 & 4) Transmission Impairments: noise, distortion, etc. (Section 3.3) Ideally received info, m’, should be identical to original input info, m (Ch. 7) If not, error correction may help restore m (Ch. 7) Else, retransmission is required (Ch. 7) COE 342 (T042) – Dr. Marwan Abu-Amara

COE 342 (T042) – Dr. Marwan Abu-Amara Networking Point to point communication not usually practical Devices are too far apart Large set of devices would need impractical number of connections (full connectivity of N nodes is N  (N – 1) / 2) Solution is a communications network Wide Area Network (WAN) Local Area Network (LAN) COE 342 (T042) – Dr. Marwan Abu-Amara

COE 342 (T042) – Dr. Marwan Abu-Amara Wide Area Networks Large geographical area Rely in part on common carrier circuits Alternative technologies Circuit switching Packet switching Frame relay Asynchronous Transfer Mode (ATM) COE 342 (T042) – Dr. Marwan Abu-Amara

COE 342 (T042) – Dr. Marwan Abu-Amara Circuit Switching Dedicated communications path established for the duration of the conversation e.g. telephone network COE 342 (T042) – Dr. Marwan Abu-Amara

COE 342 (T042) – Dr. Marwan Abu-Amara Packet Switching Data sent out of sequence Small chunks (packets) of data at a time Packets passed from node to node between source and destination Used for terminal to computer and computer to computer communications COE 342 (T042) – Dr. Marwan Abu-Amara

COE 342 (T042) – Dr. Marwan Abu-Amara Frame Relay Packet switching systems have large overheads to compensate for errors Modern systems are more reliable Errors can be caught in end system Most overhead for error control is stripped out Variable-length packets (called frames) COE 342 (T042) – Dr. Marwan Abu-Amara

Asynchronous Transfer Mode (ATM) Evolution of frame relay Combines circuit switching & packet switching Little overhead for error control Fixed-length packets (called cells) Anything from 10Mbps to Gbps Constant data rate while using packet switching technique COE 342 (T042) – Dr. Marwan Abu-Amara

COE 342 (T042) – Dr. Marwan Abu-Amara Local Area Networks Smaller scope Building or small campus Usually owned by same organization as attached devices Data rates much higher Usually broadcast systems Now some switched systems and ATM are being introduced COE 342 (T042) – Dr. Marwan Abu-Amara

COE 342 (T042) – Dr. Marwan Abu-Amara LAN Configurations Switched Switched Ethernet May be single or multiple switches ATM LAN Fibre Channel Wireless Mobility Ease of installation COE 342 (T042) – Dr. Marwan Abu-Amara

Metropolitan Area Networks (MAN) Middle ground between LAN and WAN Private or public network High speed Large area COE 342 (T042) – Dr. Marwan Abu-Amara

Networking Configuration COE 342 (T042) – Dr. Marwan Abu-Amara