Telecommunications
Network Management 
Standards and Architecture

Standards

•	Definition
•	A standard is a specification that describes the performance requirements and interface parameters of a piece of equipment, a network, or a software program
•	Most standards are market-driven
•	But it’s not a standard until it’s defined and published through some recognized forum

Standards-setting Organizations

•	International Organization for Standardization (ISO)
•	voluntary, nontreaty international organization composed of official national standards organizations
•	promotes standards that facilitate international exchange and commerce
•	responsible for the Open Systems Interconnection (OSI) architecture
•	International Telecommunications Union
•	formed in 1865
•	now a United Nations organization -- 160 member nations
•	two principle groups
•	ITU-T (Telecommunications)
•	ITU-R (Radio)
•	works through study groups that work in four-year increments
•	ITU-T (Telecommunications) -- was:
•	Consultative Committee on International Telegraphy and Telephony (CCITT)
•	standard setting committee of the Interna-tional Telecommunications Union (ITU)
•	It’s a UN treaty organization -- members are government entities
•	focuses on telephony and data transmission issues
•	defined X.400, X.500, X.25, and ISDN standards
•	The American National Standards Institute (ANSI)
•	nonprofit association of various standards-setting organizations
•	doesn’t develop standards, but publishes and disseminates them
•	more business oriented than other organizations
•	responsible for X12 EDI and FDDI

•	Institute of Electrical and Electronics Engineers (IEEE)
•	independent association -- major contributor to ANSI
•	concentrates on local area networks
•	brought order to the LAN field by stabilizing different sets of related standards

Factors In Choosing Vendors and Systems

•	Ability to make use of installed telecommunications resources
•	Support for mainstream systems
•	Ability to implement new standards
•	Ability to handle computing, information management and other relevant areas
•	Ability to upgrade facilities quickly and easily

The OSI Model

•	World wide standard supported by most vendor and user organizations
•	Its seven-layer structure encompasses all communications functions
•	Its purpose is to provide a basis for connecting dissimilar open systems
•	Does not specify particular protocols

The OSI Model

•	Application Layer
•	Presentation Layer
•	Session Layer
•	Transport Layer
•	Network Layer
•	Data Link Layer
•	Physical Layer

1. Physical Layer

•	Specifies the physical interface between the sending/receiving device and the transmission medium
•	Specifies the electrical standards and signaling parameters
•	This is the only layer where data actually moves between separate systems

2. Data Link Layer

•	Transforms a crude transmission path into an error-free link
•	error detection and correction
•	flow control
•	Divided into two layers in LAN systems:
•	media access control (MAC) -- access to the transmission medium
•	logical link control (LLC) -- error correction and detection and flow control

3. Network Layer

•	Concerned with:
•	network addressing
•	establishing and terminating connections
•	routing of information
•	partitioning info into blocks or packets (sending)
•	reassembling packetized data into the original message format (receiving)

4. Transport Layer

•	Establishes end-to-end reliability
•	ensures that messages arrive error-free and in the proper sequence
•	controls the choice of network service options available
•	provides the requested quality of service
•	makes efficient use of the network through multiplexing where appropriate

5. Session Layer

•	Establishes and terminates connections
•	Manages the exchange of information based on the relevant protocol
•	Determines whether the transmission is half-duplex or full-duplex
•	Determines when a terminal sends and receives

6. Presentation Layer

•	Primarily responsible for formatting data and transforms formats
•	from sending terminal or application to lower layers of mode
•	from lower layers of mode to receiving terminal or application
•	Performs code conversion, data compression, and data encryption

7. Application Layer

•	Coordinates communication  between applications that reside in different systems linked across a network
•	log on and password identification
•	file transfer, access, and management
•	e-mail and messaging exchange (X.400)
•	transfer and editing of documents across multivendor systems
•	virtual terminal services

Internetworking

•	Proliferation of LANs as the core resource in today’s business environment
•	Internet -- union of interconnected separate networks
•	Subnetworks -- the individual networks that make up the internet
•	Connected by bridges, routers, and gateways
•	Bridges, routers, and gateways are all combinations of hardware and software
•	The simpler the function, the more it’s handled by hardware (bridges)
•	The more complex the function, the more it’s handled by software (gateways)

Bridges

•	Interconnect two subnetworks that use identical protocol structures
•	Makes two LANs operate as one
•	Operates on levels 1 and 2 of OSI
•	Why not one big network?
•	geographic limitations
•	performance and reliability
•	fault detection

Routers

•	Connect dissimilar types of subnetworks with protocols compatible with OSI
•	Operate at layer 3 of the OSI
•	More complex than a bridge
•	different addressing structures on subnets
•	different packet size limits on subnets
•	different hardware and software interfaces
•	differences in reliability among subnets

Gateways

•	Interconnects totally dissimilar subnetworks
•	Generally links a proprietary network with an OSI network
•	Incorporates all seven layers of OSI and all the proprietary protocols
•	Conversion takes place at the application level -- gateway includes all applications (software) used on the net 

Architecture

•	Definition:  the technical strategy of an organization -- the blueprint for all decisions regarding the network over time and across technologies, uses, volumes, and geographic location
•	Balances central coordination of the infrastructure with decentralized use -- must be flexible and adaptable

Architecture

•	Should specify these things:
•	types and makes of mainframes/computers, workstations, terminals, controllers, etc.
•	standards for making various connections between
•	LAN to LAN
•	LAN to mainframe
•	subnetwork to subnetwork
•	terminals to mainframes and outside public networks

Policies For Choosing An Architecture

•	Should not block business initiatives
•	Should allow response to competitors
•	Should facilitate electronic alliances
•	Should allow flexibility
•	Should block third-party intrusions
•	Should provide sufficient international capability