CENG 210 Chapter 1: Data Communications and Networking

• CENG 210 covers Communications and Networks Fundamentals
• Chapter 1 introduces Data Communications and Networking
• The lecture objectives include defining data communications and networks, discussing different types of networks, introducing protocol layers, and introducing the TCP/IP protocol model

Data Communications

• Data communication occurs with data exchange between two devices using transmission media
• Data communication depends on delivery, accuracy, timeliness, and jitter

Data Communication Components

• A data communication system involves Message, Sender, Receiver, Transmission Medium, and Protocol
• Messages can be text represented as Unicode, numbers represented in binary, images as bit patterns using RGB or YCM, audio as analog or digital signals, and videos as continuous/combined images

Data Flow Types include:

• Simplex where communication is one-way
• Half-duplex, with each station able to send or receive, but not simultaneously
• Duplex, with both stations sending and receiving at the same moment

Networks

• Networks interconnect devices for communication; the devices can be hosts (computers, phones, etc.) or connecting devices (routers, switches, modems, etc.)

Network Criteria

• Performance, which is measured by transit time and response time
• Reliability, measured by the failure frequency and recovery time
• Security, which must protect against unauthorized access and data loss

Physical Structures

• Networks involve two or more devices connected through links
• There are two possible connection types: point-to-point and multipoint

Physical Topology

• Physical topology is the arrangement of a network
• Four basic topologies exist
• Mesh, Star, Bus, and Ring
• Hybrid toplogies are also available, composed of the basic topologies connected together

Network Category

• The network type is primary categories: LAN, MAN, and WAN
• Local Area Networks (LAN), Metropolitan Area Networks (MAN), and Wide Area Networks (WAN)

Internet

• Internet is when two or more networks are connected together
• The Internet (uppercase I) is the well known global network itself composed of millions of interconnected networks
• To access the Internet, one needs to be physically connected to an ISP

Protocols

• A protocol is a set of rules governing data communications, defining what, how, and when to communicate
• Key elements of a protocol: Syntax, Semantics, Timing

Standards

• Standards are used to ensure interoperability by providing guidelines for manufacturers, vendors, etc.
• There are two categories, standards are de facto standards and de jure standards
• De facto standards are adopted through widespread use without formal approval
• De jure standards are legislated with official recognition
• An example of an Internet standard = IETF
• Example of a de facto standard is The Internet
• An example of a de jure standard is electrical safety standards used by home appliances

Network combination

• A network is composed of hardware and software

Protocol Layering

• Layering divides complex communication tasks; needs protocol at each layer
• Protocol defines rules for communication
• The TCP/IP protocol suite are layers, each with specific functionalities

Protocol Layering Principles

• Bidirectional layers perform opposite tasks
• Corresponding layers at both ends should be identical

TCP/IP Protocol Suite Overview

• Uses a hierarchical structure of interactive modules
• Supports layers through provided services
• The layers are: Application, Transport, Network, Data Link, and Physical

Addressing

• Communication requires two addresses: source and destination
• Application layer uses User friendly addresses
• Network layer uses 32 bit IPv4 addresses
• Transport layer uses 16 bit port numbers
• Data link layer uses 48 bit MAC addresses

OSI Model

• The purpose of the OSI model is to facilitate communication between different systems without requiring changes to the logic of the underlying hardware and software
• The OSI model is not a protocol; it is a model for understanding and designing a network architecture that is flexible, robust, and interoperable
• Established in 1947, the International Organization for Standardization (ISO) is a multinational body dedicated to worldwide agreement on international standards
• An ISO that covers all aspects of network communications is the Open Systems Interconnection (OSI) model, introduced in the late 70s

Key components of the chapter include:

• Various parts of data communication
• Types of data flow
• Different connection types
• Topologies
• Networks, standards and protocols
• TCP/IP suite
• The OSI Model