Web: http://www.andrew.cmu.edu/course/90-702/

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


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

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

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


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

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


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


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


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


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


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


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


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


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)


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)

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

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



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)


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


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


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


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


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


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


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


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

NetBIOS
7 Application Layer
6 Presentation Layer
5 Session Layer
4 Transport Layer
NOS drivers hardware
3 Network Layer
2 Data Link Layer
1 Physical Layer
End User Interface
Data Translation
Time Management
Messages
Packets
Frames
Data Bits

OSI
Application
Presentation
Session
Transport
Network
Data Link
Physical
TCP/IP
Process or application
FTP, Telnet, or SMTP
TCP/UDP
Internet
Network Access
Or Local Network
IBM SNA
End User Applications
Presentation Services
Data Flow
Transmission Control
Path Control
Data Link
Physical

Network Operating
System
Driver
Version &
Specs
System Board
BIOS
NIC Card Configuration
NOS Version and Manufacturer
Hardware
Network Application

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