Transcript Chapter 4

Chapter 4:
Telecommunications and
Networking
Telecommunications &
Networking
Telecommunications
- communications
(both voice and
data) at a distance
 Networking - the
electronic linking of
geographically
dispersed devices

The Need for Networking
 Sharing
of technology resources
 Sharing of data
 Distributed data processing and
client/server systems
 Enhanced communications, including
Electronic Data Interchange (EDI) and
access to the Internet
Telecommunications &
Networking: The Big Pieces
Analog vs. digital
signals
 Media
 Topology
 Network types
 Protocols

Modem
 An
abbreviation for modulator/
demodulator
 A device that converts data from digital
form to analog form so that it can be
sent over the analog telephone network
(as well as reconverts data after it has
been transmitted)
Speed of Transmission
 bandwidth
- difference between highest
and lowest frequencies (cycles per
second) that can be transmitted on a
particular medium - a capacity measure
 Hertz - cycles per second
 baud - signals sent per second
 common measure - bits per second
(bps)
Types of Transmission Lines
 Private,
or dedicated lines
 Switched lines
------------------------------------ Simplex transmission
 Half-duplex transmission
 Full-duplex transmission
Transmission Media
 Twisted
pair
 Coaxial cable - baseband and
broadband
 Wireless, including microwave , radio
frequency, infrared light
 Satellite
 Fiber optics
New Satellites
 Over
a dozen new projects proposed
 1,700 satellites to be launched in the
next ten years, compared to the present
150 commercial satellites
 Low earth orbit (LEO) satellites - only
400 to 1000 miles above the earth,
compared to geosynchronous satellites
at 22,000 miles above the equator
New Satellites (continued)
 Iridium
-- 66 satellites to offer mobile
telephony, paging, and data
communications (Motorola, Lockheed
Martin, Sprint)
 Loral’s Globalstar - 48 satellites, similar
services to Iridium
New Satellites (continued)

Teledesic - 840
satellites, Internet
access, corporate
networking, desktop
videoconferencing
(Craig McCaw, Bill
Gates)
Telecommunications
Transmission Speeds
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Twisted pair - voice telephone 14,400 bps -56,000 bps
Twisted pair - conditioned
56 kbps - 144 kbps
Twisted pair - LAN
4 mbps - 100 mbps
Coaxial cable - baseband
10 mbps - 264 mbps
Coaxial cable - broadband
10 mbps - 550 mbps
Radio frequency wireless LAN 2 mbps - 8 mbps
Infrared light wireless LAN
4 mbps - 16 mbps
Microwave / Satellite
64 kbps - 50 mbps
Fiber optic cable
100 mbps - 30 gbps
Topology of Networks
 Bus
topology
 Ring topology
 Star topology
 Tree, or hierarchical, topology
 Mesh topology
 More complex topologies
Network Types
 Computer
telecommunications network
 Private branch exchange (PBX) network
 Local area network (LAN)
 Backbone network
 Wide area network (WAN)
 Internet
Local Area Networks
 Contention
bus network (e.g., Ethernet)
- uses CSMA/CD protocol
 Token bus network
 Token ring network
New LAN Technology
 Fast
Ethernet: Ethernet (contention bus)
operating at speeds up to 100 mbps
 Fiber Distributed Data Interface
(FDDI): Token ring architecture
delivered on a dual ring at speeds up to
100 mbps
Backbone Networks
 Middle
distance networks that
interconnect LANs in a single
organization with each other and with
the organization’s WAN and the
Internet
 Employ high-end LAN technology,
often operating at 100 mbps or more
Backbone Network Terminology
Hub - simple device
connecting one
section of a LAN to
another
 Bridge - connects
two LAN segments
when the LANs use
the same protocols

Backbone Network Terminology
(continued)
 Router,
or gateway - connects two or
more LANs together; networks may use
different protocols
 Switch - connects more than two LANs
that use the same protocol into a
backbone network
Wide Area Networks
 Direct
Distance Dialing (DDD)
 Wide Area Telephone Service (WATS)
 Leased line (most common, T-1 lines)
 Satellite (C-band, KU-band)
 Value added network (VAN)
 Integrated Services Digital Network
(ISDN)
Value Added Network, or VAN
A
data-only, private, nonregulated
telecommunications network that uses
packet switching
 An organization may choose to buy the
services of a VAN to implement its
wide area network (WAN)
Packet Switching
A
method of operating a digital
telecommunications network in which
information is divided into packets of
some fixed length that are then sent
over the network separately
 Permits more efficient use of the
network
ISDN - Integrated Services
Digital Network
 An
emerging set of international
standards by which the public
telephone network will offer extensive
new telecommunications capabilities including simultaneous transmission of
voice and data over the same line - to
telephone users worldwide
ISDN - Integrated Services
Digital Network
 Offered
over twisted pair wiring “B” or bearer channels, “D” or data
channels
 Basic rate - two B channels of 64 kbps
(thousand bits per second), one 16 kbps
D channel - all over one twisted pair
 Primary rate - 23 B channels of 64 kbps,
one 64 kbps D channel - all over two
twisted pairs
ISDN - Uses
 Customer
service application customer’s records automatically sent
to service representative’s workstation
when a customer calls in
 Economical and efficient way to solve
dial-in headaches into a corporate
network for telecommuters, branch
offices
New WAN and LAN Technology
 Asynchronous
Transfer Mode (ATM):
Switching technology employing fast
packet switching; an emerging standard
for broadband ISDN, with speeds from
1.544 mbps up to 622 mbps; many
prognosticators believe that ATM
represents the future for both LANs
and WANs
Internet
 Network
of networks that use the
TCP/IP protocol, with gateways
(connections) to even more networks
that do not use TCP/IP
 Internet applications - e-mail, Usenet
newsgroups, listserv, FTP, Gopher,
Archie, Veronica, World Wide Web
Intranet
A
network operating within an
organization which employs the
TCP/IP protocol
 The organization uses the same Web
browser, Web crawler, and Web server
software as it would on the Internet, but
the intranet is not accessible from
outside the organization
Network Protocols

An agreed-upon set
of rules or
conventions
governing
communications
among elements of a
network (or, to be
more precise, among
layers or levels of a
network)
Network Protocols
 OSI
(Open Systems Interconnection)
Reference Model - an emerging
standard
 TCP/IP (Transmission Control
Protocol/Internet Protocol) - standard
used on the Internet and IU network
 SNA (Systems Network Architecture) an IBM standard
Changing Nature of
Telecommunications/Networking
 Decreasing
price/performance ratio
-- faster transmission, cheaper
 More wireless options
 Increased standardization
 Increased usage of TCP/IP protocol
 Greater management complexity due to
anytime/anywhere access and support