PPT Slides by Dr. Craig Tyran & Kraig Pencil
Computer Networking – Part 1
MIS 320
Kraig Pencil
Summer 2014
PPT Slides by Dr. Craig Tyran & Kraig Pencil
A. Game Plan
• Introduction
• Distributed processing
• Client/Server processing
• Local area networks
• Other networks (Part 2 notes)
PPT Slides by Dr. Craig Tyran & Kraig Pencil
B. Introduction1. Motto for Sun Microsystems:
– “The network is the computer.”– Sometimes it’s hard to distinguish
between what is running on yourcomputer and what is on another computer.Example: U:drive files
PPT Slides by Dr. Craig Tyran & Kraig Pencil
B. Introduction2. A computer network may include
Communications media, Devices,
Protocols, and Software
needed to connect two or more computer devices.
3. Key goals– Enable information sharing and exchange
• Recall “Communication” (from the 5 Cs)
– Share technology resources• e.g., peripheral devices, processing,
applications, storage space
PPT Slides by Dr. Craig Tyran & Kraig Pencil
C. Distributed Processing1. Objective
– Provide access to computer processing power
2. Three well known information “architectures”
– #1: Mainframe environment• Many people log into one big computer
– #2: PC environment• People have “stand-alone” PCs
PPT Slides by Dr. Craig Tyran & Kraig Pencil
C. Distributed Processing2. Well known information “architectures” (cont.)
– #3: Client/server environment• Computers are networked together
• Processing and/or storage is shared across two or more computers
• Most popular architecture
• Have you ever useda client/servernetwork???
PPT Slides by Dr. Craig Tyran & Kraig Pencil
D. Client/Server Processing1. Role of client
– Provide user interface (“front end”)• a web browser
• a file navigation window
• an application window
– May also perform processing
– Example of a simple client• A smart phone
– Capture input, display output
• Tablet computer(maybe)
PPT Slides by Dr. Craig Tyran & Kraig Pencil
D. Client/Server Processing3. Role of server
– “Back end”– Manage the data
• Store data
• Retrieve data requested by client
– Some or most of the processing for a business task may be handled at the server
– Example• See figure
Images from www.ibm.com and www.cdfreaks.com
PPT Slides by Dr. Craig Tyran & Kraig Pencil
Client/Server Implementation for Pay Raises
Begin
End
DSS for Pay Raise
PPT Slides by Dr. Craig Tyran & Kraig Pencil
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
D. Client/Server Processing (cont.)6a. Model 1: “Thin Client”
– Pros• All processing done on powerful, fast server
• Server can store large amounts of data
• Many users have access to the data
• Save $$: buy inexpensive client computers
• Users learn only the client interface
– Cons• Server may slow down: requests from many users
• Network or server interruptions can stop all work.
• IT staff may need training to manage the server
Server
Client
PPT Slides by Dr. Craig Tyran & Kraig Pencil
D. Client/Server Processing (cont.)6b. Model 5: “Smart Client” (data is stored on
server; copied to/from client as needed)– Pros
• Use the power of the army of client computers
• Save $$: buy inexpensive server computer
• Continue working when network/server goes down
• Manage the server easily
– Cons• 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
Server
Client
PPT Slides by Dr. Craig Tyran & Kraig Pencil
E. Local Area Networks (LAN)1. Many client/server systems are connected
via a LAN
2. Typical distance range of LANs– 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)
PPT Slides by Dr. Craig Tyran & Kraig Pencil
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• Star• Ring • Bus
PPT Slides by Dr. Craig Tyran & Kraig Pencil
G. LAN Protocols1. Key challenge
• 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”• 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 Protocols3. Well known protocol: Ethernet
– Bus topology
– 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.)
– 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– Ring topology
– 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
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