1
|
- Chapter 6
- Information Systems Management In Practice 5E
- McNurlin & Sprague
|
2
|
- The flow of information within and among the corporate office,
departments, and individuals analogous to traffic on a highway.
- Building of systems - IS department responsible for designing, building,
and maintaining IS in same way as government is for the streets, roads,
and highways.
- Managed by users - both systems are managed by users, not builders.
- Standards - must be issued for highway (enforced by police) and message
traffic
|
3
|
- New telecommunications infrastructure is being built
- The telecom industry is being transformed
|
4
|
- The Internet has arrived for business use: Beginning in 1994, because of
the invention of WWW - a hyper-linked graphical layer of the Net. Funded by DOD in 1960, intended for
electronic shipment of large scientific and research files. Built as a
distributed network, without a controlling node.
|
5
|
- The worldwide telephone system has been so effective in connecting
people because it has been based on common standards worldwide.
- Closed vs. open networks: closed network - one that is offered by one
supplier and to which only the products of that supplier can be
attached. Open networks are based
on international standards so products of many manufacturers can be attached.
- Seven layer OSI reference model guides the development for computer
networks.
|
6
|
- Analogy of mailing a letter: - see Figure 6-2
- Control information (address and type of delivery) is on the envelope -
determines the services provided by the next lower layer and addressing
information for next lower layer. When a layer receives a “message” from
the next higher layer, it performs the requested services and “wraps”
the message in its own layer of control information. It passes the “bundle” to the layer
directly below it. On the receiving end, a layer receiving a bundle from
a lower layer unwraps the outermost layer of control information,
interprets the information, and acts on it.
|
7
|
- 7 - Application Layer: contains the protocols embedded in the
applications used, e.g., HTTP, FTP for transferring files in Internet,
X.500 Directory Services, X.400 Mail Handling, postscript
- 6 - Presentation: translate data to and from language and format of
7; e.g. NetBIOS to communicate
among peripherals
- 5 - Session: control the dialog for a session and acts as a moderator
and sees that messages are sent as directed; e.g., Secure Sockets Layer (SSL) to
provide Internet security
|
8
|
- 4- Transport Layer: handle flow control and ensure integrity of each
message, resequencing portions of data packets to ensure reliable packet
delivery; TCP-Transmission Control Protocol
- 3- Network Layer: route packets to their destination; IP- Internet
Protocol, allows packets to traverse an “Internet”
|
9
|
- 2 - Logical Link: protocols do error correction; LAN protocols, such as Ethernet and
Token Ring, work here
- 1 - Physical Layer: defines the physical connection of the devices to
the network; defines electrical and mechanical characteristics of
connections, characteristics of transmission wires (e.g., DS1, coax)
|
10
|
- Wireless will be the leading access technology because people are
mobile, PC may be next era cell phone
- Personal area networks (PANs)
- LANs
- The last mile
- Long distance
- M-commerce
|
11
|
- To connect a laptop computer to a cell phone or to connect computers in
a room creating an ad hoc LAN or to create a PAN in one’s office
- PAN is a short distance network
(30 ft.)
- Uses:
- Synchronize a laptop and a PDA
- Dispense money to a toll booth
|
12
|
- Advantage: used in hazardous environments, where no wiring ducts
available, disaster recovery, and temporary installations.
- 1. Infrared light LANs - transmit at frequencies in the lowest frequency
in the light spectrum.
Transmitters and receivers in sight with each other. Wide BW. Can be licensed anywhere.
- 2. Narrowband radio frequency (RF) - transmit on a center
frequency. RF transmitters must
be licensed, government regulates radio signals.
|
13
|
- Spread Spectrum LANs use RF bands that are allocated to wireless nets
by FCC, signal is spread by transmitting a chirp pattern, receiver
accepts signals it can decode. RF-noisy environment.
- Wireless LANs topologies - see Figure 6.5
- 1. Peer Level System: Each unit communicated with every other unit. Low
cost and no master control needed.
Breaks down as traffic grows.
- 2. Centrally Controlled System (client-server): Central controller is
linked to a wired LAN. Control unit handles all communications, and has
centralized network management and access control.
|
14
|
- Uses RF technology between a home or business and a telephone company’s
central office.
- Also called “fixed wireless,” this technology is being used in
developing countries and remote locations in place of wire line.
- Networks are rapidly deployed
- Less costly
|
15
|
- The most familiar wide area wireless technology is cell phones.
- Standards
- Global Systems for Mobile Communications (GMS)
- Time division for Multiple Access (TDMA)
- Code Division Multiple Access (CDMA)
|
16
|
- Technologies:
- 1G, first generation cell phones used analog technology and circuit
switching
- 2G, second generation cell phones use
- Digital technology and circuit switching
- Carry data and messages using short messaging service (SMS)
- 2.5G Upcoming, will extend 2G digital technologies (GSM, CDMA and TDMA)
- 3G Upcoming, will provide WANs for PCs and multimedia
|
17
|
- M-Commerce stands for “Mobile Commerce”
- Objective: Being able to conduct commerce digitally from wireless
devices
- Technology: Cellular radio technology at higher frequencies than cell
phones. Transmitters and
receivers have lower power, thus cells are smaller.
|
18
|
- Wireless services used for LANs and PCSs are in the microwave
range. Are they safe for humans?
|
19
|
- The IS Department plays three roles:
- Create the telecom architecture for the enterprise
- Connectivity
- Interoperability
- Operate the network
- Stay close to the forefront of the field
|
20
|
- The Telecom world is:
- Big and getting bigger
- Complex
- The telecom world has caused a great impact in the new economy
- E-mail, Web sites, transactions, and business
- Generations of Internet economy
|