Title: Telecommunications and Networks
1Telecommunications and Networks
2Telecommunications and Networks
- telecommunications
- the components of a telecommunications system.
- several telecommunications applications.
- the benefits of a network.
- basic types of communications media
- telecommunications hardware and the role
- network topology five alternatives.
3Communications
- Telecommunication
- The electronic transmission of signals for
communications, such as telephone, radio and
television - Data communications
- a subset of telecommunications involving
computerized data, but not voice communications.
Sender
Receiver
Signal
4Overview of Telecommunications Systems
5Telecommunications
6- The hardware and software that transmits
information from one location to another - Components
- Hardware Modems, switches, routers, front-end
processors, so on. - Media Twisted-pair wire, cable, microwave radio,
so on - Networks Internet, intranet, wide area, local
are, client/server, - Software Network operating systems,
telecommunications software - Data communication providers AOL, CompuServe,..
- Protocols TCP/IP, ..
- applications
7Telecommunications Media
8Basic Communications Channel Characteristics
- Simplex channel
- Half-duplex
- Full-duplex channel
- Bandwidth
- The range of frequencies that an electronic
signal occupies on a given transmission medium. - The broader the bandwidth, the more information
that can be carried - Broadband
- Telecommunications in which a wide band of
frequencies is available to transmit information,
allowing more information to be transmitted in a
given amount of time.
9Communication Media and Channels
- Anything that carries an electronic signal and
interfaces between a sending device and a
receiving device
10Types of Media
- Twisted-Pair
- Coaxial Cable
- Fiber-Optic Cable
- Microwave Transmission
11(No Transcript)
12Telecommunications Devices
13Telecommunication Signals
- Analog signals
- Continuous waves
- Information conveyed by changing wave
characteristics (amplitude and frequency) - Digital signals
- Discrete pulses
- Information conveyed in binary form (on or off
pulses) - Easily understood by computer
14Communication Processors
- Hardware devices utilized in data transmission
and reception - Modem
- Multiplexor
- Front-end processor
15Modems
- Analog signals continuous
- Digital signals discrete
- Modulation translating digital data to analog
- Demodulation translating analog data to digital
- Modems modulate demodulate data
16- Multiplexers
- devices that combine signals from several
computers to allow them to be sent over a single
transmission line. - Front end processors
- computers that manage communications to and from
a computer system. This relieves the main
computer of work so that it can be free to
process other tasks. Front end processors are
usually mainframes or midrange computers.
17Carriers and Services
18Telecomm Carriers and Services
- Telecomm carriers provide telecomm technology
and services for data communication - Common carriers long-distance phone companies
- Value-added carriers companies that have
developed private telecommunications systems and
offer their services for a fee.
19Telecomm Carriers and Services (continued)
- Telecomm services
- Switched lines transmission is routed along
path to destination - Dedicated lines continuous connection is
established - Wide-area Telecomm Service (WATS) lower cost
long distance telephone service, refers to the
use of toll-free numbers - Integrated Services Digital Network (ISDN) high
speed data transmission over existing phone lines - Digital Subscriber Lines (DSL) - high speed
digital transmission over existing phone lines - Phone dialing services - caller ID, Intelligent
dialing - T1 Carrier
20Transmission Speeds
21Networks Distributed Processing
22- A collection of computers and devices connected
by communications channels - Facilitates communications among users and allows
users to share resources with other users - share data and information
- share hardware
- share software
23Basic Processing Strategies
- Centralized processing
- all processing is done at one location.
- When
- High level of control required
- Security is a key issue
- Remote sites do not have expertise to operate
system - Decentralized processing
- different locations have their own processing
devices. Devices at different locations arent
connected together. - When
- Local independence is required
- Efficiency, based on local needs, is requirement
- Remote sites possess individualized skills
required for local computing tasks - Distributed processing
- computers at different locations are connected by
a communications network
24Network Concepts Considerations
- Network topology
- Network types
- Local Area Networks
- Wide Area Networks
- International networks
- Home small business networks
25- What is a network topology?
- The configuration, or physical arrangement, of
the devices in a communications network - Networks usually use combinations of five
topologies - Ring
- Bus
- Star
- Hierarchical
- Hybrid
26Fig 6.15
27Computer Network Type
- Networks may be classified by size
- Local Area Networks (LANs)
- Wide Area Networks (WANs)
- The Internet
- Connections to the Internet are through
- LANS
- Internet Service Providers (ISP)
28Local Area Network (LAN)
- Limited geographical area such as a home, school
computer laboratory, office building - Any topology possible
- Designs
- Peer-to-peer
- Client-server
29Local Area Networks
30LAN Components
- Network cabling physically connects each
component to the network - Hub a device that allows cables to be connected
together - Network interface card allows network cabling
to be connected to a computer - Network Operating System software that controls
the network - Bus a main cable to which all clients and
servers are connected - Ethernet - protocol for transmitting packets over
a bus
31- What is a network operating system?
- The system software that organizes and
coordinates the activities on a local area
network - Also called a network OS or NOS
- Functions
- AdministrationAdding, deleting, and organizing
users and performing maintenance tasks - File management locating and transferring files
- Printer management Prioritizing print jobs and
reports sent to specific printers on the network - Security Monitoring and, when necessary,
restricting access to network resources
32- What is a peer-to-peer LAN?
- A simple, inexpensive network that typically
connects less than 10 computers together - Each computer on a peer-to-peer network can share
the hardware, data, or information located on any
other computer in the network - Each computer stores files on its own storage
devices
33- What is a client/server LAN?
- A network in which one or more computers act as a
server and the other computers on the network can
request services from the server
34- A network that covers a large geographic area
using a communications channel that combines many
types of media - Can be one large network or can consist of two or
more LANs connected together - The Internet is the worlds largest WAN
35WAN
Ontario
California
Norway
Wide Area Network
Belgium
Manitoba
Pennsyl- vania
British Columbia
Japan
Dominican Republic
Chile
36- What is a metropolitan area network (MAN)?
- A backbone network that connects local area
networks in a metropolitan area such as a city or
town - Handles the bulk of communications activity, or
traffic, across that region
37Network Types
- International networks
- Home and small business networks
- HomePLC (powerline cable) network
- Uses the same lines that bring electricity and
power into your home. - Phoneline network
- Uses existing telephone lines in the home.
- HomeRF (radio frequency) network
- Uses radio waves, instead of cables, to transmit
data.
38Connecting Computers in a Distributed System
- Terminal-to-Host
- In a terminal-to-host configuration, users have
dumb terminals connected to a host computer. All
file access and processing is done on the host - File Server
- In a file server environment, the file or
database resides on a host computer, the file
server, and applications, including the database
management system, run on the users computer.
All processing is done on the users computer.
When an application needs a record, the file
server sends the whole file. - Client/Server
39- Client/server processing
- Applications can be divided into presentation,
applications, and data management components - Components can be partitioned between the server
and the clients to form different
implementations. - Peer-to-peer processing
- Simplified form of client/server
- Devices attached to network have access to all
other devices - No file server involved
- Simple set up and maintenance
- Implemented in many operating systems such as
Windows 2000 and Windows XP
40Communications Software and Protocols
41Network Communication Software
- Needed to provide a number of network functions
- Check for errors
- Format messages
- Maintain communication logs
- Ensure data security and privacy
- Provide message translation
42Network Communication Software (continued)
- Components
- Network Operating System enables all devices on
network to communicate - Network Management Software simplifies human
network management tasks - Protocols specify rules that govern device
communication over the network and ensure
communications among computers of different types
and from different manufacturers
43Network Communication Software (continued)
- Types of Protocols
- Ethernet
- Transmission Control Protocol/Internet Protocol
(TCP-IP) - SNA
44Ethernet
- A LAN network protocol that allows personal
computers to contend for access to the network - Based on a bus topology, but can be wired in a
star pattern - The most popular LAN because it is relatively
inexpensive and easy to install and maintain - original Ethernet standard not very fast by
todays standards, but works well for small to
medium networks - Fast Ethernet transmits data and information at
speeds up to 10 times faster than the original
standard - Gigabit Ethernet provides an even higher speed
of transmission, with speeds up to 10 times
faster than Fast Ethernet
45TCP/IP(Transmission Control Protocol/Internet
Protocol)
- Sends large files accurately over different
systems - The primary communications protocol of the
Internet - A technology that manages the transmission of
data by breaking it up into packets - Packets Data is divided into small pieces called
packets - Routers Devices that direct packets along the
fastest available path - packet switching Technique of breaking a message
into packets, sending the packets, and then
reassembling the data
46Switching and Routing
- Circuit Switching
- Physical end-to-end circuit
- Phone voice service
- Packet Switching
- Connectionless
- Division of data into packets
- Packets have data and addressing information
- Packets handled individually by routers
- Data is reassembled at the destination
47Packet Switching
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48SNA
- Systems Network Architecture (SNA)
- Introduced by IBM in 1974
- IBM proprietary communications architecture and
protocols. - The structure of SNA is a layered architecture
much like OSI. But it does not provide full
scale support of the OSI protocols.
49Communication Between Protocols
- Open Systems Interconnection (OSI) model
- A standard model for network architectures that
divides data communications functions into seven
distinct layers to promote the development of
modular networks that simplify the development,
operation, and maintenance of complex
telecommunications networks
50Open Systems Interconnection (OSI) model
- Application Layer
- Presentation Layer (HTTP)
- Session Layer
- Transport Layer (TCP)
- Network Layer (Internet Protocol)
- Data Link Layer
- Physical Layer (Packet switching, Router)
51Internet Protocol andthe Protocol Stack
Network layers
Web Browser
Web Server
Upper Level Application info.
Middle Level Data description
Lower Level Network hardware
Network Card
Network Card
52Bridge, Routers, and Gateways
53- Bridges
- a bridge connects two local area networks that
use the same protocol at the second layer of the
OSI model, the Data Link layer. - Routers
- connect networks that use different data link
layer protocols. A router looks at the address on
the message and determines which network to send
it over. - Gateways
- connect networks that use different protocols in
the top layers of the OSI stack. Gateways
reformat messages so that they can be understood
by dissimilar networks. - Switches
- are now replacing bridges and gateways in many
places.
54Typical Topologies
- Several LANs can be connected via bridges
- LANs can be connected to external networks via
gateways
Star
Star
Backbone
Star
Network Access Point
Network Access Point
Ring
Bus
WAN
LANs
55Telecommunications Applications
56Telecomm Applications
- Electronic Mail computer-based messaging
- Videoconferencing group meetings between
separate locations - Electronic Data Interchange electronic
transmission of routine business transactions - Electronic Funds Transfer electronic processing
of financial transactions
- Facsimiles electronic document transmittal
- Telecommuting working at home via telecomm
links - Distance Learning classes offered on same
time/different place, or different time/
different place basis
57Electronic Data Interchange, (EDI)
- The computer-to-computer exchange of data between
companies or trading partners - For example,
- Using EDI, the a purchase order would be created
on the computer and sent directly to the
suppliers computer, which would receive it and
initiate the processing. All of the suppliers
computer systems would use the same database of
information. The invoicing system, for example,
would be notified (by the computer application)
when the paint is shipped, and an invoice would
automatically be electronically transmitted to
ABCs computer. ABCs computer would schedule the
invoice for payment (which would also be done
electronically using electronic funds transfer
between banks).
58Chapter Summary
- Components of a telecomm system
- Types of communication media used in telecomm
systems - Types of networks
- Ways to organize network processing
- Ways to utilize networks in businesses today