Lesson Plan. Preparation. TEKS Correlations:

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1 Lesson Plan Course Title: Telecommunications and Networking Session Title: Topologies and Access Methods Lesson Duration: This lesson will take approximately 150 minutes (2.5 hours) [Lesson length is subjective and will vary from instructor to instructor] Performance Objective: Upon completion of this assignment, the student will be able to describe and design the major topologies used in computer networking. Specific Objectives: Differentiate between a logical topology and a physical topology Describe and design a bus network Describe and design a ring network Describe and design a star network Describe and design a mesh network TEKS Correlations: Preparation (4) The student acquires an understanding of telecommunication and data network services (K) differentiate between local area networks and wide area networks (5) The student analyzes various types of configurations and upgrading (E) recognize the differences among computer network topologies (6) The student recognizes and recommends the various types of network components to address industry needs (A) analyze various types and components of networks (B) analyze the characteristics of networks used to select the optimum configuration for an industry solution Instructor/Trainer The instructor must have a strong knowledge of network topologies and terminology including the type of cabling, connectors, and scenarios for the following network types: Bus Ring Star Mesh References: Conduct an online search for information on network topologies Conduct an online search for network tutorials Instructional Aids: 1

2 Topologies Presentation Topologies Handout 1 Topologies Handout 2 Topologies Quiz Materials Needed: Paper (for printed assignments) Equipment Needed: Computer that can be used by instructor to demonstrate how to use the application for creating interactive network diagrams (Handout 1) Computers with an application for creating interactive network diagrams installed for students to use Learner Students must understand these basic networking terms and concepts: 1. Network a. LAN b. MAN c. WAN 2. Networking Media (Twisted pair [TP], Untwisted Pair [UTP], Fiber Optics) 3. Traffic 4. Fault-tolerance 5. Workstation/Node 6. Hub 7. Switch 8. Central Device Introduction MI Introduction (LSI Quadrant I): Greet students as per your routine. Lead into the discussion by asking students how they hear about breaking news, whether it is world news or what is going on in the lives of their friends. Ask them to think about how information travels around the school/their group of friends: is it organized like a straight line (first person tells the second, second person tells third etc.)? A circle (first person is retold by last person)? Is it random and moves around like how the strings in a fishing net are connected? Ask someone in the class to draw on the board a diagram of how (s)he thinks information travels through his/her group of friends (or school). Based on the drawing, explain how this would be a logical or theoretical map of how information travels. Now, arrange several students in a ring holding hands. Draw on the board a map of how the students are arranged. Explain that the diagram you drew represents a true physical representation of how the students are arranged, much like a map of a state/city/etc. 2

3 Explain that just like the exercises you just demonstrated the same things are done in the world of networking. We call these layouts the network topology and that there are logical topologies and physical topologies. Explain that the logical and physical topologies do not always look the same. Tell the students that they will be studying physical network topologies and learn under what circumstances each topology should be used. Outline MI Outline (LSI Quadrant II): Instructor Notes: Defining topology: The physical arrangement of devices on a network is the network topology. It literally refers to how and where equipment is connected to the network. Define a node as any device attached to the network that is capable of processing and forwarding data. Define a backbone as a cable that serves as a common path and often employs high-speed network cable such as fiber-optic There are four major topologies: Bus Star Ring Mesh The first network to be discussed is the simplest and most inexpensive to build but the easiest to break: Bus Explain that sometimes the network topology is a hybrid (it is formed by combining one or more of the major network topologies) Uses a single cable to connect all the devices to each other and often serves as a backbone to link other topologies On slide 4: Regarding missing terminator: signal bounce occurs when the signal/packet simply travels endlessly between the two ends of the network. No new signals can get through Slide 5: Under Cons, point this out: Not Scalable: When you add nodes, you decrease network performance because the nodes share bandwidth Difficult to troubleshoot: Single point of failure means if the cable is damaged or broken in one place, none of 3

4 the nodes can transmit data Second network to discuss is Ring: Ring is slightly more expensive than bus Repeater is a device that regenerates a signal Active topology: all workstations participate in delivery of data TP: Twisted pair Token passing: Ring networks function through token passing. Tokens are 3-byte packets or control frames. Think of a clock face. If the 12 o clock computer wants to send a message to the 11 o clock computer, it must send the data all the way around with each hour checking to see if the message is intended for them. When each hour determines that the data is not for it, it forwards the signal to the next computer in line. In token passing, the token travels the ring until it gets a signal from a computer stating, I need to send data. When the token passes that computer again, the data is attached to the end of the empty token and sent to the next computer in line and so on until the correct node receives the data. The receiving computer attaches an acknowledgement or ACK, which is a verification of receipt to the token, and puts it back on the network. The token returns (still traveling clockwise) to the sending computer. The 4

5 sending computer then puts the now empty token back on the network for use by another node. The third topology is the Star. Star provides for centralized management of the network with a centralized device in the form of a hub or switch. Last topology is the Mesh Tell students that in order to keep networks manageable, they need to divide them into sub-nets (sub-networks) that are connected to each other by switches/bridges/routers The Mesh requires an extensive amount of cabling and usually no centralized management High fault tolerance is due to the fact that if one cable breaks between nodes, there is another route for the data to take to get to the node Application Adding a device requires connecting the device to every other device on the network, which is why scalability is more difficult than with star network MI Guided Practice (LSI Quadrant III): Give students Interactive Network Diagrams Handout 1: The instructor will demonstrate how to use the application for the class. Connect a computer with the application installed to an overhead projector. Students should have access to a computer on which they can work along with the instructor and create a map of a small bus network (four computers) with each computer labeled as Node 1, Node 2, etc... MI Independent Practice (LSI Quadrant III): Give students Interactive Network Diagrams Assignment (Handout 2). They should complete this portion of the assignment individually. Students should print the topologies they design and submit for review to the instructor. There should be some 5

6 leeway given for the design process; however, they must include all components required. Summary MI MI MI Review (LSI Quadrants I and IV): Have students develop a list of questions based on the presentation. Collect the questions and review them for appropriateness. Divide the students into pairs and redistribute the questions (making sure no student gets their questions to answer). Have the students answer the questions and then review them as a class. Evaluation Informal Assessment (LSI Quadrant III): The instructor will monitor student progress during the independent practice portion of the lesson and ensure that the students understand how to use the application and the concepts of the different topologies. The teacher will use this time to reteach/redirect as needed. Formal Assessment (LSI Quadrant III, IV): Students will take a quiz to ensure mastery of the material. 6

7 Interactive Network Diagrams Handout 1 1. Find the shortcut for the application and open the program. 2. Note that when the program opens, it may not have the grid lines; let s go ahead and have the grid lines visible for ease of design. a. Look at the top of the program window and click on: Options > Grid Lines i. You should now see the grid lines 3. Hover the mouse pointer over the black and blue button under Format. This is the Object Libraries link. Click on the Object Libraries button and a new window opens. 4. The new window should auto open to the General library. It will have everything you need to complete this set of lessons. a. Notice that all the icons represent basic networking equipment. i. Routers ii. Servers iii. PCs iv. Printers 5. In this exercise, we are going to create a 4-node bus topology. a. In the Object Libraries window, click on the Pc1 icon b. Now click on the button that looks like an upside-down top hat (it is the hide button). i. It will send the Object Libraries window to the background c. Now you should be back at the graph pad looking at a box drawn with a dotted line and a cross in the middle of it. d. Pick a place somewhere near the top left corner of the grid and left click with your mouse in order to place your first PC node. i. Note: The selection does not reset. Every time you click, it will place a PC node wherever you click until you change the instruction. e. Now, right click on your PC1 and choose Properties f. In the box Object Name, rename PC1 to Node 1 and click OK i. Note that on the grid, the component is now renamed Node 1 g. Repeat steps a f, renaming each node with the correct number until you have four nodes. 7

8 h. Now we need to connect the nodes together. We do this by clicking on the link button and choosing the media we want to use to connect our network. In this case, click on the link button; in the drop down box next to it, choose 100baseT as your connection media. i. Now your pointer should look like an upward pointing arrow. Click on Node 1 and then click on Node 2. A straight grey line should now connect the first two nodes. j. Repeat step i until all the nodes are connected. Congratulations! You have diagramed a 4-Node Bus topology. Like all buses, it has a single cable connecting the nodes, and it consists of less than 10 computers/nodes. You can save the sketch as a Network Notepad file or export it to a bitmap file. You also have the option of printing the file; however, make sure that if you choose to print the file, you select the option to Scale to Paper Size in printer options before you print. Spend some time getting familiar with the application so that you can complete the next assignment on your own. 8

9 Interactive Network Diagrams Handout 2 Independent Practice In this assignment, you will create the following network topologies in the application and print the assignment for a grade. Each node should have a unique name (i.e. Node 1A, Node 1B, Node 2A, Node 2B, etc. with the number denoting which question the network correlates to). 1. Bus network with the following components: a. 9 PC nodes b. Connected by 10baseT media 2. Ring network with the following components: a. 8 PC nodes b. Connected by 100baseT media 3. Star network with the following components: a. 2 servers b. 8 PC nodes c. 2 print devices d. Connected by 100baseT media 4. Mesh network with the following components: a. 1 router b. 11 PC nodes c. 5 print devices d. Connected by fiber optic media 9

10 Interactive Network Diagrams Handout 2 Independent Practice Grading Key/Guide For this exercise, the students should have a fair amount of freedom to design their networks. The primary shapes should be as follows: Bus Star Ring Mesh Deductions are as follows: Missed node/print device = - 1 point Incorrect media type = - 2 points Unlabeled nodes = - 1 point 10

11 Name: Network Topologies Quiz 1. On a bus network, each computer transmits the packet to the next computer in line. The receiving computer removes the packet from the bus. True or False 2. On a ring network, a packet is transmitted to each computer in the ring in counterclockwise order. True or False For each of the following questions, what network topology is most appropriate? Choose from bus, star, ring, and mesh. 3. A small real estate office has four computers that need to share a printer. 4. A bank has four locations in one town. All branches must link to each other and to a central office. 5. A school district has eight campuses and wants to connect all of them to the administrative offices downtown but not to each other. For each of the following questions, draw the appropriate network topology and answer the question regarding the transmission of packets. 6. Draw a bus network with four nodes. Label each node A, B, C, and D. 7. In the above diagram, if Node B is transmitting to Node C, circle the nodes that will receive the transmitted packets. 8. Draw a star network with four nodes attached. Label the nodes A, B, C, and D. 9. If Node A is transmitting packets to Node D, circle the nodes that will receive the transmitted packets. 10. Which topology requires the least cable? Which topology is the most fault-tolerant? 11

12 Name: KEY Network Topologies Quiz 1. On a bus network, each computer transmits the packet to the next computer in line. The receiving computer removes the packet from the bus. True or False 2. On a ring network, a packet is transmitted to each computer in the ring in counterclockwise order. True or False For each of the following questions, what network topology is most appropriate? Choose from bus, star, ring, and mesh. 3. A small real estate office has four computers that need to share a printer. Ring 4. A bank has four locations in one town. All branches must link to each other and to a central office. Mesh 5. A school district has eight campuses and wants to connect all of them to the administrative offices downtown but not to each other. Star For each of the following questions, draw the appropriate network topology and answer the question regarding the transmission of packets. 6. Draw a bus network with four nodes. Label each node A, B, C, and D. A B C D 7. In the above diagram, if Node B is transmitting to Node C, circle the nodes that will receive the transmitted packets. See circles drawn in question Draw a star network with four nodes attached. Label the nodes A, B, C, and D. A C B D 9. If Node A is transmitting packets to Node D, circle the nodes that will receive the transmitted packets. See circles drawn in question 8. 12

13 10. Which topology requires the least cable? Which topology is the most fault-tolerant? Least cable is bus topology. Most fault-tolerant is mesh. 13