Computer Networks Lecture 2 PDF

Computer Networks Lecture 2 Chapter 01 Introduction ◼ Data Communications and Networking, With TCP/IP protocol suite Sixth Edition ◼ Behrouz A. Forouzan ◼ © 2022 McGraw Hill, LLC. All rights reserved. Authorized only for instructor use in the classroom....

Computer Networks Lecture 2 Chapter 01 Introduction ◼ Data Communications and Networking, With TCP/IP protocol suite Sixth Edition ◼ Behrouz A. Forouzan ◼ © 2022 McGraw Hill, LLC. All rights reserved. Authorized only for instructor use in the classroom. ◼ No reproduction or further distribution permitted without the prior written consent of McGraw Hill, LLC. Chapter 1-Part 2: Outline ◼ 1.4 PROTOCOL LAYERING ◼ 1.5 TCP/IP PROTOCOL SUITE ◼ 1.6 THE OSI MODEL 3 Protocol Layers and Service Models ◼ Computer network architecture is complex ◼ Solution ➔ ◼ Computer networks functions are designed and implemented as layers ◼ Layers are logical groupings of all the processes or functions required for effective data exchange ◼ Layer n-1 provides some service to the layer n through a well- defined interface (boundary between each two layers) ◼ Each interface defines what information, operations, and services a layer must provide for the layer above it. ◼ These layers are distributed across all nodes in the network Layers, protocols, and interfaces. Figure 1.18 Communication through an internet ▪ Some devices do not use all layers. ▪ Complexity of an entity increases with the number of layers that it supports Advantages of Layered Architecture ◼ Breaks the complicated communication process into layers of simpler processes which allows easier hardware or software implementation ◼ Each layer implements distinct set of protocols (functions) which means that : ◼ The implementation of each layer can be done independently of the other layers. ◼ This allows different manufacturers to supply the hardware and software needed to the different layers ➔ encourages collaboration & Competition ◼ Well-defined layers interfaces allow changing the implementation of one layer with a completely different implementation without affecting the other layers Standard Protocol Models ◼ The protocols of the various layers are called protocol stack ◼ Two Standard Protocol models (stack) exist: ◼ Open System Interconnect (OSI) ◼ Transmission Control Protocol/Internet Protocol (TCP/IP) OSI Model ◼ Developed by ISO in 1970s ◼ Provides framework for standardization ◼ Describes how data and network information moves from an application in one computer to an application in another computer. ◼ Dominated before 1990 An open system is a set of protocols that allow any two different systems to communicate regardless of their underlying architecture OSI Model OSI Model To remember the 7 layers is the sentence “All people seem to need data processing” OSI Protocols Implementation ◼ A protocol layer can be implemented in software, in hardware, or in a combination of the two ◼ Application, Presentation, Session and Transport are implemented in software ◼ Network is a mixed implementation of hardware and software ◼ Physical and data link are implemented in hardware in the network interface card (NIC) Peer-to-Peer Processes Peers are entities (processes, hardware devices) on two or more machines communicating at a given layer OSI model-Basic Operation ◼ Peer-to-Peer communication: Each layer on a sending node communicates (logically) with its peer layer on the receiving node using formatted blocks of data called Protocol Data Units (PDU)