Transcript ppt - AD Book Enterprises

7/12: Ch. 6 Telecommunications
• Business Value of Telecommunications
• Trends
– Industry
– Technology
– Application
• Internet applications
• Network models
– WANs, LANs, Internetworks, Intranets, Extranets,
Client/Server, Interorganizational
Business Value
• How businesses use telecommunications
– enterprise collaboration
– electronic commerce
– internal business
• Business Value of
Telecommunications
– overcoming barriers:
geographical, time, cost,
structural
Trends
• Industry
– increased number of suppliers
– deregulation act create more suppliers
• Technology
– Open systems increase connectivity
– Digital overtakes analog
– Wireless
• Application
– applying telecommunications to every aspect of
busines
Internet Applications
•
•
•
•
•
•
•
origins: ARPANET – Defense Dept. project
WWW – Tim Berners-Lee at CERN (Switz.)
Email
Usenet (newsgroups)
IRC (chat rooms, AIM)
FTP
Telnet
Network Models
• basic model:
– terminal – processor – channel – processor – terminal
– includes software at most points
Network Models
• WAN – Wide Area Network
• LAN – Local Area Network
– network servers, shared peripherals, etc.
• Internetworks – Networked LANs
– using processors: switches, routers, hubs, gateways
• Intranets & Extranets – WWW for internal &
external use -- VPNs
• Client/Server – applications reside on server
– client programs reside on terminals (PCs)
Part 2: Alternatives
• Media choices
– Twisted pair, coaxial cable, fiber optics, microwaves,
satellites, cellular phone systems, wireless LANs
• Processors
– Modems, multiplexers, internetwork processors
• Software – common functions
• Network Topologies
– Star, bus, ring
• Architecture & Protocols
– TCP/IP, OSI
Media Choices
• Twisted Pair Wire
– telephone wire
• Coaxial Cable
– cable TV
• Fiber Optics
– glass fibers use light to transmit data
images courtesy of mag-nify.educ.monash.edu.au, www.mars-cam.com, 3Com.com
Media Choices
• Terrestrial Microwaves
– line-of-sight up to 30 miles apart
• Communication Satellites
– DirectPC, DirectTV
• Cellular Phone Systems
• Wireless LANs
– radio, infrared
images courtesy of mitsubishi.com
Processor Choices
• Modems
– Analog modems (telephone)
– ISDN, Cable, DSL modems
• Multiplexers
– allow multiple users on same channel
– FDM, TDM, STDM
• Internetwork Processors
– switches, hubs - complete connections
– routers, gateways – interfaces for networks
image courtesy of 3Com
Software
• Access control
– autodialers, log-ins, etc.
• Transmission control
– error checking (parity checking)
– transmission of data, etc. (often file transfer)
• Network management
– prioritizes traffic on network
– prevents (or deals with) data collisions, etc.
• Security management
– includes encryption, access validation
Network Topologies
• nodes, hubs, backbones,
servers
• Star
– central server control
• Bus
– like a highway
• Ring
– control gets handed
off from node to node
Architecture & Protocols
• circuit-switched networks
– telephone conversation: whole circuit reserved
• packet-switched networks
– shared passages, packets of information being sent
– Internet: packet-switched (ex. TCP)
Internet Protocol (IP)
• address: 4 separate 3-digit numbers separated by
periods
• looking up IPs at Internic.net
– URLs are used to look up IP addresses at Domain
Name Servers (DNS)
165.134. 1 . 25
209.145.150. 10
Transmission Control Protocol (TCP)
• breaks message into manageable chunks and
sends them separately
• like packing up a house’s contents to move
big
file
#1
#2
#3
#4
#5
#6
#7
#8
#9