MANAGEMENT INFORMATION SYSTEMS
Chapter 11
Chapter 11: LAN / WAN And Open System Interconnection
In MIS
11.1 Learning Outcomes
After complete this lesson, you would be able to:
 Know the various categories of Networks have been used in
Management Information Systems.
 Identify the various types of topology have been used in Local Area
Networks (LAN).
 Discuss the advantages and disadvantages of various types of
topology.
 Explain about OSI model and the seven layers of OSI model.
11.2 Line Configuration
 Line configuration refers to the way two or more communication
devices attach to a link.
 A link is the physical communication pathway.
 There are two possible line configurations: point-to-point and
multipoint.
11.2.1 Point-To-Point
 Provides a dedicated link between two devices.
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11.2.2 Multipoint (Multidrop)
 More than two devices share a single link.
11.3 Categories Of Networks
 There are 3 primary categories of networks: LAN, MAN, and WAN.
11.3.1 Local Area Network (LAN)
 LAN is usually privately owned and linked the devices in a single
office, building, or campus.
 LAN can be extend throughout a company and include voice, sound,
and video peripherals.
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 It is designed to allow resources (h/w, s/w, or data) to be shared
between personal computers / workstations.
 Beside size, LANs are distinguished from other types of networks by
their transmission media and topology such as bus, ring and star.
 Traditionally, LANs have data rates in the 4 – 16 Mbps range.
However its speed is increasing today and can reach 100 Mbps with
gigabit system.
11.3.2 Metropolitan Area Network (MAN)
 It is designed to extend over an entire city. I.e. it can be a single
network (cable television network) or connecting a number of LANs
into a larger network.
 A MAN may be wholly owned and operated by a private company or
be a service provided by a public company.
11.3.3 Wide Area Network (WAN)
 It provides long-distance transmission of data, voice, image and video
information over large geographical areas that may comprise a
country, or even the whole world.
 WANs may utilize public, leased, or private communication devices,
usually in combinations, therefore span an unlimited number of miles.
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 A WAN that is wholly owned and used by a single company is often
referred to as an enterprise network.
11.4 Internetworks
 Internetwork / internet is refer as when two or more networks are
connected.
 Individual networks are joined into internetworks by the use of
internetworking devices (such as routers, gateways).
 Intranet: a generic term used to mean an interconnection of networks.
 Internet: the name of a specific worldwide network.
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11.5 Topology
 Topology of a network is the geometric representation of the
relationship (peer-to-peer or primary-secondary) of all the links as
linking devices. It refers to the way a network is laid out, either
physically or logically
 Basic topologies: star, bus, and ring
 Peer-to-peer: all the devices share the link equally. E.g. ring, bus
 Primary-secondary: one device controls traffic and other must
transmit through it. E.g. star, bus.
11.5.1 Star
 Each device has a dedicated point-to-point link only to a central
controller (hub), which act as an exchange.
 Advantage: Easy to install and reconfigure; robustness and easy fault
identification and fault isolation.
 Disadvantage: Whole network down when hub is not working
Node
Node
HUB
Node
Node
11.5.2 Bus
 It is a multipoint line configuration, where one long cable acts as a
backbone to link all the devices in the network.
 Nodes are connected to the bus cable by drop line (a connection
running between the device and main cable) and taps (a connector).
 Advantage: easy of installation; less cable than, star topology.
 Disadvantage: there is a limit on the number of taps a bus can support
and on the distance between those taps – cause by heat (signal
reflection) and losing of energy during transmission; difficult
reconfiguration and fault isolation
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11.5.3 Ring
 Each device has a dedicated point-to-point line configuration only
with the two devices on either side of it. Each device in the ring
incorporates a repeater.
 Signal is passed along the ring in 1 direction.
 Advantage: Easy to install and reconfigure, Simplified fault isolation.
 Disadvantage: Media and traffic consideration – maximum length and
number of devices); A break in the ring can disable the entire
network.
Node
Node
Node
Node
11.6 The OSI (Open System Interconnection) Model
 International Standards Organization (ISO) is a multinational
body dedicated to worldwide agreement on international standards.
 An ISO standard that covers all aspects of network communication is
the Open System Interconnection (OSI) model.
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11.6.1 Layered Architecture
 A typical computer networking within a business contains the
following components: Computers, centrally located wiring
concentrators, wires and its connectors and jacks, disk drivers,
computer applications (e-mails, word etc), computer programs and
etc).
 To keep the pieces mentions above working together harmoniously
and to allow modularity between them, network architecture model is
necessary where it places the appropriate network pieces in layers.
 The model consists of 7 separate but related layers, each of which
defines a segment of the process of moving information across a
network. Each layer in the model defines what services either
hardware or software or both provide.
 The scheme shown below basically the architecture model adopted by
the ISO when its members created the open system interconnection
(OSI) reference model.
 Open system: a model that allows any two different systems to
communicate regardless of their underlying architecture.
7
Application
6
Presentation
5
Session
4
Transport
3
Network
2
Data link
1
Physical
The 7-layers of OSI model
 A mnemonic for remembering the layer of the OSI model is:
Please Do Not Touch Steve’s Pet Alligator
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 Different layers perform different tasks, and the whole would not
function without the proper operation of each of its parts.
Communications s/w is no exception.
 As the message travels from A to B, it may pass through many
intermediate nodes – which usually involve only the 1st three layers
(physical, data link and network later) of the OSI model.
The network workers performing their job duties at each layer in the model
11.6.2 Organization Of The Layers
The 7-layers can be categories into 3 subgroups:
 Network support layers: physical, data link and network layer.
 Transport layer
 User support layers: session, presentation, and application
 Network support layers: deal with the physical aspects of moving
data from one device to another. I.e. electrical specifications, physical
connections and addressing, transport timing and reliability.
 Transport layer: to ensure and-to-end reliable data transmission.
 User support layers: to allow interoperability among unrelated s/w
system.
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11.6.3 Summary Of OSI Layer functions
Application
To allow access to the network resources
Presentation To translate, encrypt, and compress data
Session
To establish, manage, and terminate sessions
Transport
To provide end-to-end message delivery and error recovery
Network
To move packets from source to destination; to provide
internetworking
Data link
Organize bit into frames; to provide node-to-node delivery
Physical
To transmit bits over a medium; to provide mechanical and
electrical specification
Review Questions
1.
List and explain the categories of Networks used in Management
Information Systems.
2.
Identify the various types of topology have been used in Local Area
Networks (LAN).
3.
Discuss the advantages of various types of topology.
4.
Explain about OSI model and the seven layers of OSI model.
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