Download - Networks Class1
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Computer Networks Unit I
Simplified network model. Classification of networks : LAN,MAN,WAN and the
internet.
Protocols and protocol architecture. The OSI ref. Model, TCP/IP ref. the internet layer, the TCP layer, the application laye Comparison of the OSI and TCP/IP ref. Models.
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Overview
Need for networks.
Introduction to networks.
Classification of networks.
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Introduction to Networks
A network consists of two or more entities or
objects sharing resources and information.
A computer network consists of two or more
computing devices connected to each other toshare resources and information.
The network becomes a powerful tool when
computers communicate and share resourceswith other computers on the same network or
entirely distinct networks.
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Introduction to Networks
Computers on a network can act as a client or
a server.
Aclient is a computer that requests forresources.
A server is a computer that controls and
provides access to resources.
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Introduction to Networks
Data is a piece of information.
The computing concept hierarchy of data is
used when planning a network.
It is essential to maintain a hierarchy of data
to manage and control resources among
computers.
Network access to data must be evaluated
carefully to avoid security issues.
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Need for Networks
A computer that operates independently from
other computers is called a stand-alone
computer.
The process of printing or transferring data
from one system to another using various
storage devices is called sneakernet.
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Need for Networks
Enhance communication.
Share resources.
Facilitate centralized management.
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Enhance Communication
Computer networks use electronic mail (e-mail) as the choice for most of the
communication.
Companies can send the same information tolarge numbers of employees (company
newsletter or announcements) or customers
(purchase information).
By using networks, information can be sent to
a larger audience in an extremely fast and
efficient manner.
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Share Resources
A copy of data or application stored at a single
central location is shared over a network.
Computer peripheral devices, referred to as
additional components, can be attached to a
computer and be shared in a network.
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Peripheral devices include faxes, modems,
scanners, and any other device that connects
to the computers.
Equipments having common requirements can
be shared in order to reduce maintenance cost.
Share Resources
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Share Resources
Important data can also be stored centrally to
make it accessible to users, thereby saving
storage space on individual computers.
Computer applications, which take up a
considerable amount of storage space, can be
installed centrally on the network, saving
storage space.
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Facilitate Centralized
Management
Networks are used to assist in management
tasks associated with their own operation and
maintenance.
Using networks results in increased efficiency
and a resultant reduction in maintenance costs.
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Facilitate Centralized
Management
Software: a set of instructions or programs that
control the operation of a computer.
Software can be installed at a central location usingservers, where the installation files are made
accessible over the network.
Backing up data: saving extra copies of necessary
files.
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Classification of Networks
Classification by transmission technology
Classification by network geography.(scale)
Classification by component roles.
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Classification by TransmissionTechnology
Broadcast networks. Single communication channel shared by all the
machines on n/w
Point-to-point networks. Consists of many connections between individual
pairs of machines.
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Classification by NetworkGeography (scale)
0.1 m Circuit board
1 m System
10 m Room LAN
100 m Building LAN
1 Km Campus LAN
10 Km City MAN
100Km Country WAN
1,000 Km Continent WAN
10,000 Km Planet The Internet
Inter ProcessDistance
Processors locatedin same
Data Flowmachine
MultiComputer
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Classification by Network
Geography Networks are frequently classified according
to the geographical boundaries spanned by the
network itself. LAN, WAN, and MAN are the basic types of
classification, of which LAN and WAN are
frequently used.
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Local area network (LAN):
A LAN covers a relatively small area such as a
classroom, school, or a single building. LANs are inexpensive to install and also provide
higher speeds.
Distinguished from other n/w s by three
characteristics...1) Size 2) Transmissiontechnology 3)topology
Classification by Network
Geography
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Local area network ( bus or linearcable network)
Classification by Network
Geography
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Metropolitan area network (MAN):
A MAN spans the distance of a typical
metropolitan city.
The cost of installation and operation is higher.
MANs use high-speed connections such as fiber
optics to achieve higher speeds.
Classification by Network
Geography
Fiber-optic cableTransmit data as pulses of light through tiny tubes
of glass.
26000 times the transmission capacity of twisted
pair cable
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DQDB(DistributedQueue DualBus Metropolitan Area
Network)(IEEE802.6)
1 2 3
HeadEnd
BusA
Bus B
Direction of flow onBusA
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Metropolitan area network
Classification by Network
Geography
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Wide area network (WAN):
WANs span a larger area than a single city.
These use long distance telecommunication
networks for connection, thereby increasing the
cost.
The Internet is a good example of a WAN.
Classification by Network
Geography
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Wide area network
Classification by Network
Geography
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Network Topologies
Star Ring Tree Complete Intersecting Rings Irregular
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Classification by
Component Roles
Networks can also be classified according to
the roles that the networked computers play in
the networks operation.
Peer-to-peer, server-based, and client-based
are the types of roles into which networks are
classified.
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Classification by
Component Roles
Peer-to-peer: In a peer-to-peer network, all computers are
considered equal.
Each computer controls its own information andis capable of functioning as either a client or a
server depending upon the requirement.
Peer-to-peer networks are inexpensive and easy to
install. They are popular as home networks and for use in
small companies.
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Classification by
Component Roles
Peer-to-peer (continued):
Most operating systems come with built-in peer-
to-peer networking capability.
The maximum number of peers that can operate
on a peer-to-peer network is ten.
Each peer shares resources and allows others open
access to them.
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Classification by
Component Roles
Peer-to-peer (continued):
Peer-to-peer networks become difficult to manage
when more security is added to resources, since
the users control their security by password-protecting shares.
Shares can be document folders, printers,
peripherals, and any other resource that they
control on their computers.
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Classification by
Component Roles
Peer-to-peer network
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Classification by
Component RolesServer-based: A server-based network offers centralized control
and is designed for secure operations.
In a server-based network, a dedicated server
controls the network.
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Classification by
Component RolesServer-based (continued):A dedicated server is one that services the network by
storing data, applications, resources, and also provides
access to resources required by the client.
When a client requests a resource such as a document ,the server sends the whole resource over the network to
the client , where it is processed and later returned to
the server.
These servers can also control the networks securityfrom one centralized location or share it with other
specially configured servers.
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Classification by
Component Roles
Server-based network
Cl ifi i b
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Classification by
Component Roles
Client-based:
Client-based network servers process requests
from clients and return just the results.
These networks take advantage of the powerful
processing capabilities of both the client and the
server.
A
pplication servers and communications serversare examples of client-based networks.
Cl ifi ti b
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Classification by
Component Roles
Client-based network
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Summary
A network consists of two or more entities
sharing resources and information.
A computer network consists of two or more
computers that are connected and are able to
communicate.
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Summary
The basic purpose of networks is to enable
effective communication, share resources, and
facilitate centralized management of data.
Networks can be classified according to their
transmission technology, geographical
boundaries (scale) or their component roles.
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Internet
A network is a group of connected, communicatingA network is a group of connected, communicatingdevices. Andevices. An internetinternetis two or more networks that canis two or more networks that cancommunicate with each other.communicate with each other.
Millions ofMillions of people are users.people are users.
Collections of LAN's connected by a WANCollections of LAN's connected by a WAN