Communication Architecture and Network Protocol Layering Networks and Protocols Prepared by: TGK First Prepared on: Last Modified on: Quality checked by:

Communication Architecture and Network Protocol Layering

Networks and Protocols

Prepared by: TGK First Prepared on: Last Modified on:

Quality checked by: Copyright 2009 Asia Pacific Institute of Information Technology

Networks and Protocols Slide 2 of 27


Topic & Structure of the lesson

•Introduction to Data Communication Model

•Data Communication

•Data Communication Networking

•Protocols and Protocol Architecture



Learning Outcomes

At the end of this module, YOU should be able to:

• Explain the Networking deals with the technology and architecture.

• Explain the communication protocols in Computer Networks.



Key Terms you must be able to use

If you have mastered this topic, you should be able to use the following terms correctly in your assignments and exams:

• Networking • Entity• System• Protocol• Syntax• Semantics• PDU



Main Teaching Points

• Data Communications Model

• Networking

• Wide Area Networks

• Local Area Networks

• Protocols

• OSI Reference Model

• TCP/IP Protocol Suite



Source: generates data to be transmitted Transmitter: converts data into signals Transmission System: carries the signals Receiver: converts received signal into data Destination: takes incoming data

Data Communications Model



Data Communications Reference Model

Figure 1.1 Simplified Communication Model – William Stalling Data and Computer communication



Point to Point communication not practical Devices are too far apart Large set of devices would need impractical number of connections

Solution is a communications network

Networking



Figure 1.3 Simplified Network Model – William Stalling- Data and Computer communication

Networking



• Large geographical area• Crossing public rights of way• Rely in part on common carrier circuits• Alternative technologies

– Circuit switching– Packet switching– Frame relay– Asynchronous Transfer Mode (ATM)

Wide Area Network



Smaller scope– Building or small campus

• Usually owned by same organization as attached devices

• Data rates much higher than WAN• Usually broadcast systems• Now some switched systems and ATM are being

introduced

Local Area Network



• ENTITY - anything capable of sending or receiving info:– application program– file transfer package– e-mail package

• SYSTEM - a physically distinct object that contains one or more ENTITIES:– computer, terminals, remote sensors etc.

Protocols



For two entities to successfully communicate, they must agree on:

• What is communicated?• How is it communicated?• When is it communicated?

• Must conform to some mutually acceptable set of conventions governing the exchange of data between the entities:

PROTOCOLS

Protocols



Key Elements of Protocols

• Syntax– Data formats, Signal levels

• Semantics– Control information, Error handling

• Timing– Speed matching, Sequencing

Protocols



• Task of communication is broken up into modules• For example file transfer could use three modules

– File transfer application– Communication service module– Network access module

Protocol Architecture



Overview of NetworkingOverview of Networking Simplified File Transfer ArchitectureSimplified File Transfer Architecture

Figure 1.6 Protocol in Simplified Architecture – William Stalling – D&C Communication




Addressing RequirementsAddressing Requirements

• Two levels of addressing required• Each computer needs unique network address• Each application on a (multi-tasking) computer needs a

unique address within the computer

– The service access point or SAP




Protocol Data Unit (PDU)Protocol Data Unit (PDU)

• At each layer, protocols are used to communicate• Control information is added to user data at each layer• Transport layer may fragment user data• Each fragment has a transport header added

– Destination SAP– Sequence number– Error detection code

• This gives a transport protocol data unit




• A layer model• Each layer performs a subset of the required communication

functions• Each layer relies on the next lower layer to perform more

primitive functions• Each layer provides services to the next higher layer• Changes in one layer should not require changes in other

layers

OSI Reference Model



• Dominant commercial protocol architecture• Specified and extensively used before OSI• Developed by research funded US Department of Defense• Used by the Internet

TCP/IP Protocol Suite



TCP/IP Protocol ArchitectureTCP/IP Protocol Architecture

• Application Layer– Communication between processes or applications

• End to end or transport layer (TCP/UDP/…)– End to end transfer of data– May include reliability mechanism (TCP)– Hides detail of underlying network

• Internet Layer (IP)– Routing of data

TCP/IP Protocol Suite



Network Layer– Logical interface between end system and network

• Physical Layer– Transmission medium– Signal rate and encoding

TCP/IP Protocol SuiteTCP/IP Protocol Suite



Quick Review Question

1. List the major disadvantages with the layered approach to protocols.

2. Discuss the need or lack of need for a network layer(OSI layer 3) in a broadcast network.



Follow Up Assignment

Presentation on Layered Model Approach (OSI or TCP/IP)



Summary of Main Teaching Points

• Data Communications Model• Networking• Wide Area Networks• Local Area Networks• Protocols

Key Elements of ProtocolsProtocol ArchitectureAddressing RequirementsProtocol Data Unit (PDU)

• OSI Reference Model• TCP/IP Protocol Suite



Q & A

Question and Answer Session



Topic and Structure of next session

Network Hardware (I)

Classification of Networks (PAN, LAN, MAN, and

WAN) WAN technologies (Frame Relay, ISDN, and ATM)

Next Session

Documents

Communication Architecture and Network Protocol Layering Networks and Protocols Prepared by: TGK First Prepared on: Last Modified on: Quality checked by: