Download Networking Basics

Computer Networking – Part 1
MIS 320
Kraig Pencil
Summer 2014
PPT Slides by Dr. Craig Tyran & Kraig Pencil
A. Game Plan
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Introduction
Distributed processing
Client/Server processing
Local area networks
Other networks (Part 2 notes)
PPT Slides by Dr. Craig Tyran & Kraig Pencil
B. Introduction
1. Motto for Sun Microsystems:
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“The network is the computer.”
Sometimes it’s hard to distinguish
between what is running on your
computer and what is on another
computer.
Example: U:drive files
PPT Slides by Dr. Craig Tyran & Kraig Pencil
B. Introduction
2. A computer network may include
Communications media,
Devices,
Protocols,
and Software
needed to connect two or more computer devices.
3. Key goals
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Enable information sharing and exchange
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Recall “Communication” (from the 5 Cs)
Share technology resources
• e.g., peripheral devices, processing,
applications, storage space
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C. Distributed Processing
1. Objective
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Provide access to computer processing power
2. Three well known information
“architectures”
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#1: Mainframe environment
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Many people log into one big computer
#2: PC environment
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People have “stand-alone” PCs
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C. Distributed Processing
2. Well known information “architectures” (cont.)
– #3: Client/server environment
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Computers are networked together
Processing and/or storage is shared across two or
more computers
Most popular
architecture
Have you ever used
a client/server
network???
PPT Slides by Dr. Craig Tyran & Kraig Pencil
D. Client/Server Processing
1. Role of client
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Provide user interface (“front end”)
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a web browser
a file navigation window
an application window
May also perform processing
Example of a simple client
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A smart phone
– Capture input,
display
output
Tablet computer
(maybe)
PPT Slides by Dr. Craig Tyran & Kraig Pencil
D. Client/Server Processing
3. Role of server
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“Back end”
Manage the data
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Store data
Retrieve data requested by client
Some or most of the processing for a business
task may be handled at the server
Example
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See figure
Images from www.ibm.com and www.cdfreaks.com
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Client/Server Implementation for Pay Raises
Begin
DSS for
Pay Raise
End
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D. Client/Server Processing
(cont.)
4. Server computers
– microcomputers, servers/work stations, mainframe computers
5. Types of client/server models
– The “models” vary with regard to division of labor
• Presentation processing: e.g. show a form where the user can …
(1) view data, (2) enter data for storage, or (3) request an action, e.g.
storing data, sorting data or searching for data.
• Logic processing: Perform calculations (e.g., forecasting model)
• Data management: Store/organize data, execute data queries
– Example: See “Pay Raise System” on previous slide
– Key variations:
• Where does the presentation processing happen?
• Where does the logic processing happen?
• Where does the data management happen?
PPT Slides by Dr. Craig Tyran & Kraig Pencil
Client/Server Models
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D. Client/Server Processing (cont.)
6a. Model 1: “Thin Client”
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Server
Pros
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All processing done on powerful, fast server
Server can store large amounts of data
Many users have access to the data
Save $$: buy inexpensive client computers
Users learn only the client interface
Cons
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Server may slow down: requests from many users
Network or server interruptions can stop all work.
IT staff may need training to manage the server
PPT Slides by Dr. Craig Tyran & Kraig Pencil
Client
D. Client/Server Processing (cont.)
6b. Model 5: “Smart Client” (data is stored on
server; copied to/from client as needed)
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Server
Pros
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Use the power of the army of client computers
Save $$: buy inexpensive server computer
Continue working when network/server goes down
Manage the server easily
Cons
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Data is not easily managed/shared with other users
Clients cannot store/process large amounts of data
Network clogs because of large data transmissions
Hard to manage application software on clients
PPT Slides by Dr. Craig Tyran & Kraig Pencil
Client
E. Local Area Networks (LAN)
1. Many client/server systems are connected
via a LAN
2. Typical distance range of LANs
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Lower range: one room, one building
Upper range: multiple buildings
PPT Slides by Dr. Craig Tyran & Kraig Pencil
E. Local Area Networks (LAN)
3. Selected LAN components
– Computers
– NICs
• Network Interface Card
– Transmission media (rates)
• Twisted pair (up to 100 Mbps)
• Coax cable (up to 200 Mbps)
• Fiber optic (up to 6 Tbps)
• Wireless (Laptop – 54 Mbps)
• Microwave (up to 200 Mbps)
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F. Network Topology
1. How are the components of a LAN
physically connected?
 Topology
2. Topology: Basic geometric arrangement
of network
3. Types of topologies
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Star
Ring
Bus
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Star Network
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Ring Network
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Bus Network
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G. LAN Protocols
1. Key challenge
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How to organize lots of messages flying around the
network?
• Can all computers “talk” at once?
• Or … Do the computers wait their turn?
• If so, how do they know when it is their turn?
• How do computers know if a message is
for them?
2. These questions are addressed via “protocols”
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Protocol: A standard way to define when and how a
device can transmit data in a network
PPT Slides by Dr. Craig Tyran & Kraig Pencil
G. LAN Protocols
3. Well known protocol: Ethernet
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Bus topology
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Network sharing works like this:
• Each device randomly “listens” for quiet line;
then sends message to another device
– Analogy: A formal dinner party where people try to avoid talking
at the same time as someone else
• If two devices send a message at
the same time  Collision!!!
• If collision … then a) abort, b) wait a
random time, and c) resend
• Technical name for this process:
– Carrier Sense Multiple Access/
Collision Detection (CSMA/CD)
Image from ewake.wfubmc.edu:99
PPT Slides by Dr. Craig Tyran & Kraig Pencil
G. LAN Protocols (cont)
3. Well known protocol: Ethernet (cont.)
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Effectiveness
• Would the traditional Ethernet approach be effective for low
traffic conditions?
• Would it be effective for high traffic conditions?
4. Another example protocol: Token Ring
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Ring topology
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Electronic “token” passed around the ring from device to device
A device must possess the token to transmit a message
Circulating “token” approach prevents collisions
Effectiveness
• Can be good for higher traffic conditions since no collisions
PPT Slides by Dr. Craig Tyran & Kraig Pencil