Network Classification and Standards

1
Network Classification and Standards

• Organizational Communications and Technologies
• Prithvi N. Rao
• Carnegie Mellon University
• Web http//www.andrew.cmu.edu/course/90-702/

2
Reading

• Data Communication Fundamentals (Stallings and
  van Slyke) Chapter 5
• TCP/IP and Other Protocol Architectures
  (Stallings and van Slyke) Chapter 12

3
Objectives

• Describe the methods for classifying computer
  networks
• List the different size classification of
  networks
• List the two major types of transmission media
• List two types of switching service
• Define the layered approach to communication
  architectures

4
Objectives

• Describe the seven layers of the Open Systems
  Interconnection (OSI) model
• Compare TCP/IP and SNA architectures to the OSI
  model

5
Network Topologies and Components

• Computer networks classified in the following
  ways
• Size
• Ownership
• Type of transmission media
• Type of switching service
• Logical access method

6
Classification

• Size refers includes number of users and
  geographic location
• Local Area Network (LAN) spans less than 1 km
• Campus Area Network span 5 to 100 km and are
  privately owned
• Metropolitan Area Network (MAN) span 2 to 100 km
  and found within campuses or within and office
  complex

7
Classification

• Wide Area Network (WAN) spans more than 100 km
• WAN is the long haul network of choice and
  spans the nation or entire world

8
Ownership

• Determines who is ultimately responsible for the
  maintenance of the network components and the
  addition of new equipment
• Private
• Private businesses, universities or individuals
• Includes all cables, and intermediate equipment
• Includes most LAN and MAN
• Provide the greatest flexibility of service
• Restrict who can connect to them and distance of
  communication

9
Ownership

• Public owned by public utility companies
• Owned predominantly by the phone companies
• Some MAN and nearly all WAN networks are in this
  category
• Offer tremendous connectivity
• Provider determines connectivity and flexibility
  of service

10
Transmission Media

• Type of transmission media identifies network by
  physical media used to communicate between
  locations
• Bounded
• Cable, wire or fiber optic media in which signal
  is contained
• Various types of cables and are closely related
  to various network topologies

11
Transmission Media

• Type of transmission media identifies network by
  physical media used to communicate between
  locations
• Bounded
• Cable, wire or fiber optic media in which signal
  is contained
• Various types of cables and are closely related
  to various network topologies

12
Transmission Media

• Unbounded
• Microwave, satellite, radio wave or infrared
  media
• WAN service providers use long-haul unbounded
  media
• Typically there is a combination of media types
  used in providing services to users

13
Switching Service

• Circuit Switching
• Analogous to a telephone call
• Line is maintained throughout duration of
  conversation
• Transmission resources are dedicated and reserved
  for duration of connection
• Service is optimal for continuous or time
  sensitive information flow
• Bulk file transfer (not necessarily time
  sensitive)
• Voice
• Video

14
Switching Service

• Packet Switching
• Analogous to the postal service package can take
  several possible routes to reach destination
• Network information is broken into packets
• Transmission resources are shared by many
  connections. More than one path to destination
• Each transmission unit must contain addressing
  information
• More efficient because they share resources
• Provide best to non-time sensitive data
• Logging sessions
• Transaction processing
• Query and response systems

15
Logical Access Method

• Connection Oriented logical access requires user
  to establish connection with the receiver before
  communication can take place
• Sender and receiver must both terminate
  connection
• Applies to most voice and wide area packet
  networks
• Public switched voice network
• X.25, T1 and T3 high speed communication channels
• ISDN frame relay and ATM (Asynchronous Transfer
  Mode)
• Transmission Control Protocol (TCP)

16
Logical Access Method

• Connectionless logical assumes communication
  channel is always available
• Senders and receivers transmit without
  establishing a communications channel
• PC-LAN provide connectionless access
• Broadcast LAN (ethernet)
• Broadcast satellite transmission
• Cable TV and FM radio
• User Datagram Protocol (UDP)

17
Protocol Defined

• Agreed upon set of rules defining how devices
  communicate
• Define which language is used and the grammar and
  syntax
• Define message format

18
Standard Protocol Defined

• Set of specifications defining a specific method
  or technology for use in a fixed set of
  applications
• Hardware
• Software
• Access methods
• Message handling formats

19
Standard Setting Bodies

• Institute of Electrical and Electronic Engineers
  (IEEE)
• American National Institute of Standards and
  Technology (NIST)
• International Standards Organization (ISO)
• Internet Activities Board (JAB)
• Consultative Committee for International
  Telegraphy and Telephony (CCITT)

20
Open Systems

• Products and technologies designed and
  implemented in accordance with vendor-independent
  standards
• Distributed multi-vendor environment open systems
  enable users to achieve portability among
  applications, data and people

21
Goals of the Open Systems Movement

• Portability
• Ability to move applications and data from one
  system to another without re-programming and data
  conversion
• Scalability
• Ability to grow applications from one computer
  platform to larger more platforms in the future
• Interoperability
• Ability for a network of heterogeneous computers
  to operate with the same data and applications
  independently of one another and to use those
  applications in the native machine interface

22
The OSI Model

• International Standards Organization (ISO)
  developed layered model for supporting
  communications architecture
• Modularity was motivation
• Each layer is independent of another layer
• Protocol of one layer does not rely on the
  protocol of any specific protocol of any other
  layer for information
• Function duplication should be avoided
• Resulting OSI model not widely implemented
  although the US
• Government is pushing for acceptance of this
  architecture

23
Layer Purpose

• Application
• Provides interface between end-user services
• Email, file transfer
• All lower layers support this layer
• Presentation
• Performs protocol conversion, data encryption and
  decryption
• Performs data compression
• Concerned mainly with representation of data
  rather than content
• Interfaces to application layer above it and to
  lower level services

24
Layer Purpose

• Session
• Establishes and terminates data streams between
  network nodes
• Manages and synchronizes direction of data flow
• NetBIOS is one of the first session layer
  protocols
• Transport (TCP, SPX, XNS)
• Provides an additional layer of connection below
  session layer
• Ensures that session connections are transparent
  and handles details of data transfer
• Assembles packets for routing by the network
  layer

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Layer Purpose

• Network (IP and IPX)
• Provides routing mechanisms between nodes on a
  network
• Concerned with addressing and identification of
  nodes
• Datalink
• Defines the access method for connection with
  network
• Error detection and connection are important
  functions here
• Physical
• Determines the electrical mechanical aspects of
  network
• Responsible for bit stream transmission and error
  checking

26
OSI Summary

• Simplify model and use it as basis for discussion
• Application, Presentation and Session layers deal
  with how computers on each end handle information
  internally
• Network, Data Link and Physical layers handle
  data once it has entered the network
• Transport layer interfaces between upper and lower

27
OSI Summary

• Simplify model and use it as basis for discussion
• Application, Presentation and Session layers deal
  with how computers on each end handle information
  internally
• Network, Data Link and Physical layers handle
  data once it has entered the network
• Transport layer interfaces between upper and lower

28
OSI Model
End User Interface
7 Application Layer
6 Presentation Layer
Data Translation
NetBIOS
5 Session Layer
Time Management
4 Transport Layer
Messages
NOS
3 Network Layer
Packets
Frames
2 Data Link Layer
drivers
1 Physical Layer
Data Bits
hardware
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Comparison of OSI, TCP/IP and SNA
OSI
TCP/IP
IBM SNA
Application
End User Applications
Process or application FTP, Telnet, or SMTP
Presentation Services
Presentation
Session
Data Flow
Transport
TCP/UDP
Transmission Control
Path Control
Network
Internet
Data Link
Data Link
Network Access Or Local Network
Physical
Physical
30
Network Compatibility
Network Operating System
Hardware
Driver Version SpecsSystem Board BIOS
NIC Card Configuration
NOS Version and Manufacturer
Network Application
31
Summary

• Classification of networks based on
• Size
• Ownership
• Type of media
• Switching method
• Logical Access Method
• TCP and SNA are examples of layered approaches