network classification and standards organizational communications and technologies prithvi n. rao...
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Network Classification and Standards
Organizational Communications and TechnologiesPrithvi N. Rao
Carnegie Mellon UniversityWeb: http://www.andrew.cmu.edu/course/90-702/
Reading
Data Communication Fundamentals (Stallings and van Slyke) Chapter 5
TCP/IP and Other Protocol Architectures (Stallings and van
Slyke) Chapter 12
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
Objectives Describe the seven layers of the Open
Systems Interconnection (OSI) model
Compare TCP/IP and SNA architectures to the OSI model
Network Topologies and Components Computer networks classified in the following
ways Size
Ownership
Type of transmission media
Type of switching service
Logical access method
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
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
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
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
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
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
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
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
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
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)
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)
Protocol Defined Agreed upon set of rules defining how devices
communicate
Define which language is used and the grammar and syntax
Define message format
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
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)
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
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
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
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
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
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
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
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
OSI Model
7 Application Layer
6 Presentation Layer
5 Session Layer
4 Transport Layer
3 Network Layer
2 Data Link Layer
1 Physical Layer
End User Interface
Data Translation
Time Management
Messages
Packets
Frames
Data Bits
drivers
hardware
NOS
NetBIOS
Comparison of OSI, TCP/IP and SNA
Application
Presentation
Session
Transport
Network
Data Link
Physical
OSI TCP/IP IBM SNA
Process or application
FTP, Telnet, or SMTP
TCP/UDP
Internet
Network AccessOr Local Network
End User Applications
Presentation Services
Data Flow
Transmission Control
Path Control
Data Link
Physical
Network Compatibility
Network OperatingSystem
Hardware
Network Application
DriverVersion &Specs
System BoardBIOS
NIC Card Configuration
NOS Version and Manufacturer
Summary Classification of networks based on
Size Ownership Type of media Switching method Logical Access Method
TCP and SNA are examples of layered approaches
top related