Page 170 - DCAP207_NETWORKS_DCAP406_COMPUTER_NETWORKS

Ra Profession University Unit 11: Transport Layer

Unit 11: Transport Layer Notes

CONTENTS
Objectives
Introduction

11.1 Transport Service
11.1.1 Services Provided to the Upper Layers
11.1.2 Quality of Service

11.1.3 Transport Service Primitives
11.2 Elements of Transport Protocol
11.3 A Simple Transport Protocol
11.3.1 The Example Service Primitives
11.3.2 The Example Transport Entity

11.3.3 The Example as a Finite State Machine
11.3.4 User Datagram Protocol (UDP)
11.3.5 Transmission Control Protocol

11.4 Summary
11.5 Keywords
11.6 Review Questions
11.7 Further Readings

Objectives

After studying this unit, you will be able to:

Describe the concepts behind the transport layer services like multiplexing/demultiplexing,
reliable data transfer, flow control, congestion control

Analyze the transport services and issues involved for efficient exchange of data from
transport entity to transport entity.
Understand the transport layer primitives and examples for implementing transport
protocol.
Discuss various transport layer protocols in the Internet including UDP and TCP

Introduction

The transport layer makes the upper layers from any concern with providing reliable and cost
effective data transfer. It facilitates end-to-end control and information exchange with the quality
of service required by the application program. Thus, layer four of the OSI reference model is
the transport layer that provides transparent transfers of data between the source and destination
machines using the services of the network layer such as IP. It enables reliable internetworking
data transport services that are transparent to upper layers. The transport layer protocol

LOVELY PROFESSIONAL UNIVERSITY 163