Chapter 3
 Discuss
Network Architecture.
 Discuss
Standards.
Electronic Data Interchange
 Layered
Models
OSI Model
TCP/IP Model
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 Architecture
is an overall system plan that is implemented in a set
of hardware, software, and communication products.
 The
architecture specifies components and interfaces that make
up the systems. It includes, protocols, formats and standards to
which all hardware and software in the network must conform.
 Architecture
should include documentation of system usage,
functionality and performance parameter of all the components.
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 Network Architecture
attempts to facilitate the operation,
maintenance and growth of the communication and
processing environment by isolating the user and the
application program from the details of the network.
 Network
architecture is necessary to support distributed data
processing with multiple computers in a network.
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
Purpose
 Provide an orderly structure for the communication network that ensures a
specific level of compatibility.
 Provide isolation of the application systems from the physical hardware.
 Support faster development and easier maintenance of application systems by
using system software utilities to perform communication functions.
 Be reliable, modular and easy to use.
 Accommodate new devices and software for the network without changing the
application systems.
 Replace individual pieces of system without affecting other pieces.
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 A standard
is a set of rules or descriptions about a specific piece
of equipment, software or service.
 A standard
is a definition or format that has been approved by a
recognized standards organization or is accepted as a de facto
standard by the industry.
 Commonly,
there are two kinds of standards
Proprietary standards
Open standards
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 Standards
that are specific and unique to an organization are
called proprietary standards.
 These
proprietary standards can only be used by the
organization that designed those standards.
 Standards
that can be used by all the organization are called
open standards.
 Equipments
from various supplier are interoperable.
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 In
computing environment, middleware consist of software agents
acting as intermediary between different application components.
 Total
cost of ownership (TCO) considers all costs of using a
specific set of equipment, including purchase, installation,
maintained, and upgrade.
 de
facto – actually exercising power, although not legally or
officially established.
Example IBM SNA
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 A system
is a group of interrelated and interdependent parts
working together to achieve is a common goal.
 A cooperative
system is a specialized type of system that
requires at least two parties with different objectives but
common goals to collaborate on the development and
operation of a joint system in support of those common goals.
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 EDI
is the process of direct computer-to-computer
communication of information in a standard format between
organizations.
 This
communication permits the receiver and sender to
perform a specific set of business functions.
 EDI
is a set of standards for electronic transfer of business
documents.
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 The
primary purpose of EDI is to provide communication
standards for the electronic transfer of common business
documents between the respective computer systems of
individual and diverse trading partners.
 EDI
provides a significant opportunity to reduce the cost of
doing business and strengthen the partnership. Thus,
offering a significant competitive advantage.
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 Benefits
of using EDI
Improve customer service.
Improve accuracy of the data.
Reduce clerical errors.
Faster access to information.
Decreased administrative cost.
Reduced delivery times.
Improved cash flows.
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 Layered
models are all about boundaries; honor the boundaries
and live in freedom within the layer.
 Prototyping
– The use of one capability to emulate another,
generally in a inexpensive manner and short time frame.
 Simulation
– The process of imitating a real phenomenon with a
set of mathematical formulas. It may be achieved on a working
system by use of equipment to simulate real conditions, such as
network traffic.
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 OSI
Model stands for Open System Interconnection Model.
 OSI
model was created by the International Organization for
Standardization (ISO) and the Consultative Committee on
International Telephony and Telegraphy (CCITT).
 Exponential
growth of internet resulted in the heterogeneous
computing environment, this resulted in the creation of OSI
Model.
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 The
OSI Model consists of seven layers, each layer with specific
standards and functionality.
 The
upper most four layers are the host layers, they specify the
need of the user applications.
 The
lower most three layers are the media layers, they are
concerned with the actual communication, circuit establishment
and disconnection, message routing, and error correction and
detection.
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
The layers are hierarchical in that the lower layers provide services such
as the control information to the layer just above it.

The adherence to OSI Model makes the development of software and
hardware easier.

The OSI Model is a plan by which communication software is designed.

The model facilitates control, upgradability, replacement, and
management of the resources that make up the communication
network.
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Data
Application Layer
Data
Presentation Layer
Data
Session Layer
Segments
Transport Layer
Packets
Network Layer
Frames
Data Link Layer
Bits
Physical Layer
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 Physically
transmits the bits.
 Physically
establishes the node-to-node connection when
requested by the data link layer.
 Concerns
with the establishing duplex, half-duplex and full-
duplex transmission.
 Defines
all electrical and physical specifications for the
devices.
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 The
data link layer concerns itself with the actual characters
and the sequencing in which they are transmitted.
 This
layer segments the bits into frames, and coordinates the
flow of data over multiple physical connections.
 This
layer attempts to deliver error free data, it includes error
detection, error recovery and error correction methods.
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 The
network layer performs network routing, flow control,
segmentation/ de-segmentation, and error control functions.
 The
network layer defines message addressing and routing
methods.
 This
layer also controls congestion in the network is overloading
certain computers.
 Handles
the movements for data from one network to another.
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 The
transport layer provides a transparent transfer of data
between end users.
 The
transport layer is responsible for maintaining a reliable
and cost-effective communication channel from user’s
applications software process in one computer to a user
process in another computer.
 The
transport layer monitors the status of the connections.
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 The
session layer provides the mechanism for managing the
dialogue between end-user application processes.
 This
layers deals with establishing a logical session between
the hosts.
 The
session layer establishes the communication between
applications, enforces the rules of carrying on the dialogue,
and tries to establish the connection if a failure occurs.
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 The
presentation layer handles encoding, encryption, and
similar manipulation of the presentation of data.
 The
presentation layer is also responsible for formatting and
displaying the data to and from the application layer and
deals with the transmission format of the data.
 This
layer deals with the syntax of the data.
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 The
application layer interfaces directly to and performs
common application services for the application processes.
 This
layer interfaces to user-oriented services such as
determining the data to be transmitted, the message or
record format for the data, and the transaction codes that
identify the data to the receiver.
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Layer
Title
Action
1
Physical
Delivers bits to node to node
2
Data Link
Deliver error-free data
3
Network
Define message addressing and routing
4
Transport
Maintains reliability and cost effective communication channel
5
Session
Organize logical session
6
Presentation
Formats and displays the data, provides security, encodes, and
encrypts
7
Application
Functionally defines by the user
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 The
TCP/IP is the basic communication language or protocol
of the internet.
 It
is a collection of two communication protocols
Transmission Control Protocol
Internet Protocol
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 The
TCP manages the assembly of messages or files into
smaller packets that are transmitted over the Internet and
received by a TCP layer at the receiving end, which then
reassembles the original massage.
 TCP
is responsible for verifying correct delivery of data from
client to sever.
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 The
IP handles the address part of each packet so that it gets to
the right destination.
 TCP/IP
also can refer to an entire collection of protocols, called
TCP/IP suite. This includes
Hyper Text Transfer Protocol (HTTP).
File Transfer Protocol (FTP).
Terminal Emulation (Telnet).
Simple Mail Transfer Protocol (SMTP).
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Application Layer
Transport Layer
Internet Layer
Data link Layer
Physical Layer
Network Access
Layer
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 The
physical layer and the data link layer of OSI Model combined
is called Network Access Layer of the TCP/IP Model.
 The
physical layer is concerned with the transmission of the actual
bits.
 The
Data link layer is concerned with the framing and transporting
the packets over the physical layer.
 The
data link layer in TCP/IP and OSI Model is sub divided into
Logical Link Control (LLC) and Media Access Control (MAC).
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 The
internet layer used the Internet Protocol to send the
block of data (datagram) from one point to another.
 This
layer is also called as the Network Layer.
 Internet
protocol is the key component of TCP/IP as each
piece of data is sent over the network as an IP packet.
 IP
performs the basic task of getting packets from source to
destination.
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 The
transport layer is where the transmission control protocol
(TCP) is used by most of the Internet application such as FTP,
HTTP and Telnet.
 TCP
is a connection-oriented, the sender and receiver must
establish a connection before data can be transferred.
 The
transport layer provides a safe and reliable byte stream,
which makes sure that data arrives complete, undamaged, and in
order
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 The
application layer is the layer that most common network-
aware programs use in order to communicate across a
network with other programs.
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Application Layer
Presentation Layer
Application
Layer
TCP/IP Protocol Suit
Telnet
Session Layer
Transport Layer
Transport Layer
Network Layer
Internet Layer
Data Link Layer
Physical Layer
Network
Interface Layer
FTP
SMTP
DNS
TCP
UDP
IP
ARP
Ethernet
SNMP
Token
ring
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IGMP
Frame
relay
ICMP
ATM
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