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. Introduction 1.Motto for Sun Microsystems: –“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 –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 Processing 1.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 Processing 2. 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 used a client/server network???

PPT Slides by Dr. Craig Tyran & Kraig Pencil D. Client/Server Processing 1.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 Processing 3. 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 and

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 slideprevious 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

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 Star Network

PPT Slides by Dr. Craig Tyran & Kraig Pencil Ring Network

PPT Slides by Dr. Craig Tyran & Kraig Pencil Bus Network

PPT Slides by Dr. Craig Tyran & Kraig Pencil G. LAN Protocols 1.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 Protocols 3. 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