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?