ppt slides by dr. craig tyran & kraig pencil computer networking – part 1 mis 320 kraig pencil...

PPT Slides by Dr. Craig Tyran & Kraig Pencil

Computer Networking – Part 1

MIS 320

Kraig Pencil

Summer 2014


A. Game Plan

• Introduction

• Distributed processing

• Client/Server processing

• Local area networks

• Other networks (Part 2 notes)


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


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


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


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???


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)


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


Client/Server Implementation for Pay Raises

Begin

End

DSS for Pay Raise


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?


Client/Server Models


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


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


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


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)


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


Star Network


Ring Network


Bus Network


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


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


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

ppt slides by dr. craig tyran & kraig pencil computer networking – part 1 mis 320 kraig pencil...

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