oz – foundations of electronic commerce © 2002 prentice hall essentials of telecommunications
TRANSCRIPT
Oz – Foundations of Electronic Commerce© 2002 Prentice Hall
Essentials of Telecommunications
2 Oz – Foundations of Electronic Commerce© 2002 Prentice Hall
Learning Objectives Compare and contrast network
topologies Explain the basic functions of the TCP/IP
protocols Evaluate the limitations of the various
classes of Internet addresses Select the best Internet link service
according to organizational or individual needs
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Network Topologies A network is made up of nodes
and communication lines Network topologytopology refers to the
physical layout of the network Star Ring Bus
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Star
Ring Bus
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Peer-to-peer vs. client-server networks Peer-to-peer: each computer has
equal capabilities Client-server:
Servers offer services to clients Predominant on the Internet
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Switching Techniques Switches – devices that direct the
flow of signals and route communication traffic
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Circuit switchingCircuit switching The entire communication path is
reserved for the duration of the session
Typical of voice communication Inefficient for data communication
Resources are being wasted while reserved, but not in use
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Packet switchingPacket switching Data divided into packets Each packet travels independently
through the network Upon arriving at the final destination,
packets are reassembled Efficient solution for data
communication
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Network Protocols A set of rules that governs the flow
and processing of information in a network
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TCP/IP: IP:IP:
Addressing Packet reassembly Multiplexing Operates between hosts
TCP:TCP: Controls flow of information from client to
server
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LANs and WANs Local Area Network (LAN) – serves
a building or a campus of adjacent buildings Owned by an organization Used for internal purposes Typically linked to the Internet
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Wide Area Network (WAN) – cover large areas Employ different types of
transmission media Ex.: telephone networks, Internet
backbone, etc.
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IntranetIntranet - an internal network based on TCP/IP
ExtranetExtranet - an intranet that can also be partially accessed by customers and/or suppliers Often, LANs of two or more partners
linked through the Internet
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Virtual private networks (VPNs)Virtual private networks (VPNs) SecureSecure internal networks connected
to the Internet To be covered in more detail later
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Internet Addressing Each device connected to the
internet must be assigned a uniqueunique IP number Also called Internet address or IP
address The IP number may be temporary (just
for the duration of the connection) The IP number is made up of up to four
blocks
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StaticStatic vs. dynamicdynamic IP numbers An IP address consists of two parts,
identifying the Network, and The node within the network
IPv4 vs. IPv6
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Five network classes Class A – very large networks Class B – medium-sized networks Class C – small networks Classes D and E are currently not
assigned
Oz – Foundations of Electronic Commerce© 2002 Prentice Hall
Bandwidth, bandwidth, and more bandwidth
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Integrated Services Digital Network (ISDN) International standard Transmits voice, data, and video
over digital lines 64Kbps and 128Kbps Service offered by phone
companies Already outdated
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Cable modem Permanent connection to the
Internet Shared resource
Actual speed depends on the number of subscribers sharing the same cable
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Digital Subscriber Line (DSL) Service offered by phone companies Several standards and technologies Permanent connection Speed deteriorates with distance Most common: asymmetric DSL
(ADSL) High download speed Low upload speed
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T lines T1:
1.544Mbps Point-to-point
Not switched Dedicated Digital
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T2: A combination of four T1 lines
T3: A combination of 28 T1 lines
T1 and T3 lines form the basis of most private networks
T lines (continued)
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Asynchronous Transmission Mode (ATM) Very high speed, fiber optics
based, standard Cell switchingCell switching
A cell = 53 bytes All cells use the same route from
source to destination
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Wireless Communication Mobile communication
PDAs Wireless Internet connections
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Business considerations in telecommunications Scalability – the ability to easily
augment a network Three types of costs:
The one time investment in lines Monthly fees for leased lines Maintenance costs
Security issues
Oz – Foundations of Electronic Commerce© 2002 Prentice Hall
Essentials of Telecommunications