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

25. 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 drivers 2 Data Link Layer hardware 1 Physical Layer Data Bits

29. 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 Driver Version & SpecsSystem Board BIOS Hardware 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