Multimedia Network Protocols

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Multimedia Network Protocols
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Format

• Networking Standards
• Introduction to root concepts
• Layered models of processes
• Why do we need protocols?
• The seven layers

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Standards

• Standards are documented agreements containing
  technical specifications or other precise
  criteria that stipulate how a particular product
  or service should be designed or performed

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Networking Standards Organizations

• American National Standards Institute (ANSI)
• Electronics Industry Alliance (EIA)
• Institute of Electrical and Electronic Engineers
  (IEEE)
• International Organization for Standardization
  (ISO)
• International Telecommunication Union (ITU)

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IEEE Networking Specifications
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Protocols

• The Open Systems Interconnect (OSI) model is not
  a protocol it is a conceptual system that most
  real protocols are based upon
• Traffic lights at a junction control the flow of
  vehicles on a road system
• This is a simple, world-wide protocol
• A protocol is an agreed set of rules, an
  interface between two systems, a mutually agreed
  treaty or diplomatic document

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OSI model Why bother?

• Real-world network protocols dont implement the
  OSI seven layer protocol stack model
• But nearly all network protocols are based on a
  simplified layered model
• The layered model helps us think about the many
  processes involved in communicating over networks
• A good model provides support for thinking

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Why a Layered Model?

• Answer by providing an analogy - The Big Data
  Corporation wants 10,000 mouse mats showing its
  new corporate logo
• The CEO makes the decision, the budget is agreed,
  the requirements set and the order processed
• The order is then transferred to a manufacturer
• The order is processed, then sent to the design
  team
• The design is then created and checked
• Note that the process of handling the order goes
  through many layers within two businesses

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A Fine-Grained Breakdown

• This is a multilayer model
• It shows two different protocol stacks
• The courier service is analogous to network
  cabling (in a wired system)

President/CEO
Quality Control
Directors
Manufacture
Marketing
Design
Clerical
Clerical
Mail Room
Mail Room
Courier or Postal Service
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Communication Between Two Systems
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ISO OSI Reference Model
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Data Transformation
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The Seven Layer Model

• Please do not throw sausage pizza away!
• All PCs seem to network data poorly
• At the top, the Application layer provides OS
  services for application software
• At the bottom, the Physical layer deals with
  wiring issues

Application
Presentation
Session
Transport
Network
Data link
Physical
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The Application Layer

• Provides interface to the software enabling
  programs to use network devices
• Definition of the way that network services use
  the network
• Defines how many services work, including
• File sharing
• Network Printing
• Message Services
• and others

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Application Program Interface (API)

• Routine that allows a program to interact with
  the operating system
• Belongs to the Application layer of OSI Model
• Microsoft Message Queuing (MSMQ)
• Used in API network environment
• Stores messages sent between nodes in queues
• Forwards them to their destination

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The Presentation Layer

• This layer presents data, which is to say it
  does some pre-processing, such as
• data compression
• encryption
• character set conversion
• Translates between the application and the network

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The Session Layer

• A communications management layer
• Defines how two computers synchronise, maintain
  and close a communication session
• This includes such things as
• security authentication
• acknowledgement of data transfer
• establishing and relinquishing a connection
  identity

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The Transport Layer

• Data packet management
• Ensures that chunks of data have been transferred
  without error does lots of error and flow
  control
• Takes data and packs it into chunks or chops it
  up into chunks suitable for transmission
• Takes chunks and unpacks them or combines them
  into data streams

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The Network Layer

• This is Internet Protocol address layer for path
  selection around the network
• Routing of packets uses IP addresses

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Network Layer Address

• Resides at Network level of OSI Model
• Follows hierarchical addressing scheme
• Can be assigned through operating system software

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The Data Link Layer

• Decodes packets into what are called frames which
  contain
• Physical source and destination addressing
• data validity / error checking
• This layer is dependant on receiving packets
• The network technology being used will influence
  how this layer works e.g. Ethernet, token ring ..

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Data Link Layer Address

• Also called MAC address, after Media Access
  Control (MAC) sublayer
• Number uniquely defining a network node
• Manufacturer-hard codes the address
• Block ID
• Device ID

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IEEE Networking Specifications

• To accommodate shared access for multiple network
  nodes, the IEEE expanded the OSI Model by
  separating the Data Link layer into two sublayers
• Logical Link Control (LLC) sublayer
• Media Access Control (MAC) sublayer

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Subdivided Data Link Layer
LLC and MAC sublayers
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Data Link Layer Sublayers

• LLC
• Upper sublayer
• Provides common interface
• Supplies reliability and flow control services
• MAC
• Lower sublayer
• Appends the physical address of the destination
  computer onto the frame

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The Physical Layer

• This is the physical networking media layer which
  includes the cabling technology
• Defines the transmission technique and the
  hardware definitions (connectors and so on)
• Networking may take place over copper cables,
  optical fibres, infra-red radiation, radio waves
  and this variation should be transparent to the
  user

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Transmission Control Protocol/Internet Protocol
(TCP/IP)
OSI Model
TCP/IP
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Conclusion

• We have discussed-
• Organizations that set standards for networking
• Standard root concepts of networking
• Layered models of processes and layers in our
  conceptual model of networking
• Why protocols are required for interoperability
• Details of the seven layers of the OSI model