Chapter 3

Telecommunication Architectures and Standard

Agenda

• Network architectures & standards• Standard-making organizations• Pros and cons of standards• Open System Interconnection Model (OSI)• TCP/IP• Manufacturer architecture• Pros and cons of architecture

Network Architectures

• Design principles for– Functions– Data format– Procedures

• Describe “what”

Communication Standards

• Rules for compatibility• Specify “how”

Needs for Architectures and Standards

• Complex communication systems• Maintenance and future growth• Connectivity between network devices• Distributed processing systems• Diagnostic and performance management

Standards-Making Organizations

• International Telecommunications Union-Telecommunication Standardization Section (ITU-T)

• International Organization for Standardization (ISO)

• American National Standard Institute (ANSI)• Electrical Industries Association (EIA)• National Institute of Standards and Technology

(NIST)• Institute of Electrical and Electronic Engineers

(IEEE)

Standards• V.

– Connection of digital equipment to telephone analog line

• X.– Connection of digital equipment to telephone

digital line– X.400

• Allow communication between incompatible electronic mail systems

– X.500• Create and maintain a directory of e-mail users and

their network addresses

Pros and Cons of Standards

• Pros– Compatibility between vendors– Fewer products

• Cons– Slow processing– Obsolescence– Freezing technology– Discouraging innovation

Open System Interconnection Model• International Organization for Standardization• Interconnection of Dissimilar Network• Seven Layers

– Application– Presentation– Session Control– Transport Control– Network Control– Data Link Control– Physical Link Control

Application Layer

• Determine data to be send at originating end• Process data at receiving end

Presentation Layer

• Change data format • Compression/expansion• Encryption/decryption

Session Control Layer

• Communication rules • Rate of transmission• Accounting functions

Transport Control Layer

• Identify receiving address • Calculate and check checksum of entire

message

Network Control Layer

• Route message• Dissemble and assemble data (transmission

unit)• Accounting functions

Data Link Control Unit

• Determine line usage• Establish link between two ends• Detect and correct transmission error• Add header and trailer• Divide data unit for transmission

Physical Link Control Layer

• Hardware specification• Electrical characteristics

TCP/IP Protocol

• Transmission Control Protocol/Internet Protocol

• Advanced Research Project Agency• ARPANET

TCP/IP Structure• Application layer

– User application• Transport layer (TCP protocol)

– Communication, error-checking procedure• Internet layer (IP protocol)

– Routing• Network access layer

– Connection• Physical

– Physical & electrical interface

Manufacturers’ Architecture

• Objectives– Base for future products– Control customers

• Types– IBM: Systems Network Architecture (SNA)– Digital Equipment Corporation: Digital

Network Architecture (DNA)

Pros and Cons of Layered Architectures

• Pros– Modularize structure for simplify maintenance– Specify interfaces for easy change & future

growth• Cons

– Complex Rules– Cost of sophisticated intelligence– Complex software

Points to Remember

• Network architectures & standards• Standard-making organizations• Pros and cons of standards• Open System Interconnection Model (OSI)• TCP/IP• Manufacturer architecture• Pros and cons of architecture

Discussion

• What are your thoughts on selecting network equipment for an organization?