Data Communication & Networking: An Introduction

Data Communication & Networking: An Introduction

Dr. Indranil Sen Gupta

Data Commn. & Networking: Introduction

Slide 1

Introduction • The 1970s and 1980s have seen a merger of computer science and data communication. • Byproducts of the revolution: – No fundamental differences between data processing equipments (computers) and data communication equipments (transmission, switching). – No fundamental differences among data, voice, and video communication. – The dividing lines between uniprocessors, multiprocessors, LAN, MAN and WAN have blurred. Dr. Indranil Sen Gupta

Data Commn. & Networking: Introduction

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A Communication Model

Figure 1.1 from the book by Stallings

Dr. Indranil Sen Gupta

Data Commn. & Networking: Introduction

Slide 3

Key Elements of the Model • Source: generates the data to be transmitted (e.g. telephones, PCs). • Transmitter: transforms and encodes the information in such a way as to produce signals that can be transmitted across sore sort of transmission system (e.g. MODEM). • Transmission System: a single transmission line or a complex network connecting source and destination. • Receiver: accepts the signal from the transmission system and converts it into a form that can be handled by the destination device. • Destination: takes the incoming data from the receiver. Dr. Indranil Sen Gupta

Data Commn. & Networking: Introduction

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Some of the key tasks performed by a data communication system • Transmission system utilization • Interfacing • Signal generation • Synchronization • Error detection and correction • Flow control

Dr. Indranil Sen Gupta

• • • • •

Addressing Routing Recovery Security Network Management

Data Commn. & Networking: Introduction

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Simplified Data Communication Model

Figure 1.2 from the book by Stallings

Dr. Indranil Sen Gupta

Data Commn. & Networking: Introduction

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Networking Concepts • In its simplest form, data communication takes place between two devices that are directly connected by some point-to-point transmission medium. • Sometimes they may not be directly connected: – The devices are very far apart. – Many links may be shared.

• Solution? – Attach each device to a communications network. Dr. Indranil Sen Gupta

Data Commn. & Networking: Introduction

Slide 7

Figure 1.3 from the book by Stallings

Dr. Indranil Sen Gupta

Data Commn. & Networking: Introduction

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Networking Terminologies • LAN/MAN: – Scope is small (same room or building or Campus). – Owned by the same organization that owns the attached devices. – Data rates are typically much higher. – LANs usually employ a broadcast network approach. • No intermediate switching node • Only one station at a time can transmit packets

– Modern LAN technologies use packet/cell switching techniques. Dr. Indranil Sen Gupta

Data Commn. & Networking: Introduction

Slide 9

Contd. • WAN: – Usually covers a large geographic area. – Relies at least in parts on circuits provided by a common carrier. – Typically consists of a number of switching nodes. – Traditional technologies: • Circuit switching • Packet switching

– Recent technologies: • Frame relay • ATM Dr. Indranil Sen Gupta

Data Commn. & Networking: Introduction

Slide 10

Protocols and Protocol Architectures • A protocol is used for communication between entities in different systems. • Instead of a single module for performing communications, there is a structured set of modules that implement the communication functions. – Called the Protocol Architecture

Dr. Indranil Sen Gupta

Data Commn. & Networking: Introduction

Slide 11

TCP/IP Protocol Architecture • Most widely used inter-operable architecture. • Consists of a large number of protocols, called TCP/IP protocol suite. • Simplified layer model: – Physical: covers the physical interface between a host and the transmission medium. – Network Access: concerned with access to and routing data across a network for two end systems attached to the same network. Dr. Indranil Sen Gupta

Data Commn. & Networking: Introduction

Slide 12

Contd. – IP: used to provide routing function across multiple networks. • This protocol is implemented not only in the end systems but also in the routers.

– TCP: ensures that data is exchanged reliably. • Also known as host-to-host layer.

Dr. Indranil Sen Gupta

Data Commn. & Networking: Introduction

Slide 13

Figure 1.9 from the book by Stallings

Dr. Indranil Sen Gupta

Data Commn. & Networking: Introduction

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The OSI Model • Developed by ISO as a model for a computer communication architecture, and as a framework for developing protocol standards. • Although more systematically designed, it ultimately lost its battle to TCP/IP, which has evolved in an ad-hoc manner. • Based on a seven layer model.

Dr. Indranil Sen Gupta

Data Commn. & Networking: Introduction

Slide 15

Seven Layer Model • Application: provides access to OSI environment for users. • Presentation: provides independence to the application processes from differences in data representation. • Session: establishes, manages and terminates connections (sessions) between co-operating applications. • Transport: provides reliable, transparent transfers of data between end points; provides end-to-end error recovery and flow control. • Network: provides upper layers with independence from the data transmission and switching technologies used to connect systems. • Data Link: provides for the reliable transfer of information across the physical link. • Physical: concerned with transmission of raw bit stream over some physical medium. Dr. Indranil Sen Gupta

Data Commn. & Networking: Introduction

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Figure 1.11 from the book by Stallings

Dr. Indranil Sen Gupta

Data Commn. & Networking: Introduction

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