Transcript An Introduction to Computer Networking

An Introduction to Computer
Networking
Objectives
• Identify elements of a network
• Describe several specific uses of a
network
• Distinguish between client/server and
peer-to-peer networks
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Networks and Standalone
Computers
• Network
– Group of computers and other devices
connected by some type of transmission
media
– Networks enable users to share devices and
data, collectively called a network’s
resources
• Standalone computer
– Uses programs and data only from its local
disks and is not connected
to a network
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Local and Remote Computers
• Local computer
– Computer on which user is working
• Remote computer
– Computer that user controls or works on via
network connection
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Peer-to-Peer Network
• Computers communicate on single segment of cable and
share each other’s data and devices
• Simple example of a local area network (LAN)
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Simple peer-to-peer network
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Local Area Network (LAN)
• Network of computers and other devices
confined to relatively small space
• LANs involving many computers are
usually server-based
– On a server-based network, special
computers (known as servers) process data
for and facilitate communication between
other computers on the network (known as
clients)
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Networking Basics
• Workstation
– Computer that typically runs a desktop
operating system and connects to a
network
• Client/server architecture
– Networking model in which clients use
central server to share applications,
devices, and data
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Networking Basics
• Client/server network
– Network based on client/server architecture
• Network operating system
– Special software designed to manage data
and other resources on a server for a number
of clients
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Networking Basics
LAN with a file server
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Advantages of Server-Based
over Peer-to-Peer Networks
• User login accounts and passwords can be
assigned in one place
• Access to multiple shared resources can be
centrally granted
• Servers are optimized to handle heavy
processing loads and dedicated to handling
requests from clients
• Servers can connect more than a handful of
computers
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MANs and WANs
• Metropolitan area network (MAN)
– Network connecting clients and servers in
multiple buildings within limited geographic
area
• Wide area network (WAN)
– Network that spans large distance and
connects two or more LANs
– The Internet is an example of a very
intricate and extensive WAN that spans the
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WAN
A simple WAN
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Elements Common to All
Server-Based Networks
• Client
– In addition to referring to a computer on the
network, may also refers to human user of
client workstation
• Server
• Workstation
• Network interface card (NIC)
– Enables workstation to connect to the network
and communicate with other computers
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Elements Common to All
Server-Based Networks
• Network operating system (NOS)
• Host
– Server that manages shared resources
• Node
– Client, server, or other device that can
communicate over a network and that is
identified by a unique identifying number,
known as its network address
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Elements Common to All
Server-Based Networks
• Topology: It is the physical layout of computer network
•Commonly used network topologies are:
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Elements Common to All
Server-Based Networks
• Protocol
– Rules network uses to transfer data
• Data Packets
– The distinct units of data transmitted from one
computer to another on a network
• Addressing
– Scheme for assigning unique identifying number to
every workstation on network
– The number that uniquely identifies each workstation
and device on a network is its address
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Elements Common to All
Server-Based Networks
• Transmission media
– Means through which data are transmitted and
received
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How Networks Are Used
• Services
– Features provided by a network
•
•
•
•
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File and print services
Communications services
Mail services
Internet services
Management services
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Network Services
• File services
– Refers to capability of a server to share data
files, applications, and disk storage space
– Server that provides file services is called a
file server
• Print services
– Allows printers to be shared by several users
on a network
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Network Services
• Communications services
– Allow remote users to connect to a network
• Remote user
– Person working on a computer in a different geographical
location from the LAN’s server
– Communications server
• Server that runs communications services
• Also referred to as access servers and remote
access servers
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Network Services
• Mail services
– Coordinate storage and transfer of e-mail
between users on a network
• Gateway
– Combination of software and hardware enabling two
different kinds of networks to exchange data
• Internet services
– Enable networks to communicate with the
Internet
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Network Services
• Management services
– Centrally administer and simplify complicated
management tasks on the network
– Numerous services fall under category of
network management
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Important Management
Services
• Traffic monitoring and control
– Traffic
• Data transmission and processing activity taking
place on a computer network at any given time
– Segment
• Part of LAN that is logically separated from other
parts of LAN and that shares fixed amount of
traffic capacity
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Important Management
Services
• Load balancing
– Distributing process activity evenly across a
network so that no single device is
overwhelmed
• Hardware diagnosis and failure alert
– Determining when a network component
fails and automatically notifying network
administrators through e-mail or pager
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Important Management
Services
• Asset management
– Collecting and storing data on number and
types of software and hardware assets in an
organization’s network
• License tracking
– Determining how many copies of a single
application are currently in use on a network
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Important Management
Services
• Security auditing
– Evaluating what security measures are
currently in force and notifying network
administrator if a security breach occurs
• Software distribution
– Automatically transferring data file or program
from the server to a client on the network
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Important Management
Services
• Address management
– Centrally administering a finite number of
network addresses for an entire LAN
• Backup and restoration of data
– Backing up
• Copying critical files to a secure storage area
– Restoring
• Retrieving data if original files are lost or deleted
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