How Much Does This Cost Instructions Answers How Much Does This Cost? (Instructor Version)

Instructor Note: Red font color or Gray highlights indicate text that appears in the instructor copy only.


Explain the operation of dynamic routing protocols.

To prepare for the concepts to be learned in this chapter, students will create physical routes, record progress of travel on the physical routes, and compare/contrast recorded results. Emphasis in this activity will be: number of hops, or steps used, data time recorded to start and finish the complete route, and dropped data, if the route finish is not reached within certain parameters.


This modeling activity illustrates the network concept of routing cost.

You will be a member of a team of five students who travel routes to complete the activity scenarios. Each group will be required to have one digital camera or any device that has a camera, a stopwatch, and the provided student file for this activity. One person will function as the photographer and event recorder, as selected by each group. The remaining four team members will actively participate in the scenarios below.

A school or university classroom, hallway, outdoor track area, school parking lot, or any other location can serve as the venue for these activities.

Activity 1

The tallest person in the group establishes a start and finish line by marking 15 steps from start to finish, indicating the distance of the team route. Each student will take 15 steps from the start line toward the finish line and then stop on the 15th step—no further steps are allowed.

Note: Not all of the students may reach the same distance from the start line due to their height and stride differences. The photographer will take a group picture of the entire team’s final location after taking the 15 steps required.

Activity 2

A new start and finish line will be established; however, this time, a longer distance for the route will be established than the distance specified in Activity 1. No maximum steps are to be used as a basis for creating this particular route. One at a time, students will “walk the new route from beginning to end twice”.

Each team member will count the steps taken to complete the route. The recorder will time each student and at the end of each team member’s route, record the time that it took to complete the full route and how many steps were taken, as recounted by each team member and recorded on the team’s student file.

Once both activities have been completed, teams will use the digital picture taken for Activity 1 and their recorded data from Activity 2 file to answer the reflection questions.

Group answers can be discussed as a class, time permitting.

Required Resources

  • Digital or BYOD camera to record Activity 1’s team results. Activity 2’s data is based solely upon number of steps taken and the time it took to complete the route and no camera is necessary for Activity 2.
  • Stopwatch
  • Student file accompanying this modeling activity so that Activity 2 results can be recorded as each student finishes the route.

Scenario – Part 2 Recording Matrix

Student Team Member Name Time Used to Finish the Route Number of Steps Taken to Finish the Route

Reflection Questions

1. The photographer took a picture of the team’s progress after taking 15 steps for Activity 1. Most likely, some team members did not reach the finish line on their 15th step due to height and stride differences. What do you think would happen if network data did not reach the finish line, or destination, in the allowed number of hops or steps?
The data would not be successfully delivered. It would be dropped from the network route.

2. What could be done to help team members reach the finish line if they did not reach it in Activity 1?
Answers will vary, but students should mention increasing the number of steps (hops) allowed or removing the 15-step restriction.

3. Which person would best be selected to deliver data using the network route completed in Activity 2? Justify your answer.
The data took different amounts of time to be delivered, but it was delivered by all team members. The team member taking the shortest amount of time would be the best person to deliver the data.

4. Using the data recorded in Activity 2 and a limit of 255 steps, or hops, did all members of the team take more than 255 steps to finish their route? What would happen if they had to stop on the 254th step, or hop?
The route would not be finished (see same result from Activity 1 and 15 hop limit) and therefore, the route would not be finished – data would be dropped)

5. Use the data that was recorded in Activity 2. Would you say the parameters for the route were enough to finish it successfully if all team members reached the finish line with 255 or less steps, or hops? Justify your answer.
Yes, the numbers of steps allowed were not exceeded, therefore allowing the data to be delivered successfully.

6. In network routing, different parameters are set for routing protocols. Use the data recorded for Activity 2. Would you select time, or number of steps, or hops, or a combination of both as your preferred routing type? List at least three reasons for your answers.
Answers will vary, but students could mention:

  • Time – the shortest amount of time taken by a team member might be the preferred route.
  • Hops – if all team members finished the route within the 255 step, or hop, limit, this might be selected as the preferred route.
  • Both – the lowest number of hops taken by a particular team member in the shortest period of time might be the preferred route.

Identify elements of the model that map to IT-related content:

  • Routers use number of hops, bandwidth, delay and cost metrics to determine the best path for network communication.
  • Routing tables show records of the best routes for data delivery using the protocols configured for and reported by network traffic.
  • Network administrators have a choice as to which types of routing protocols to use for network data delivery.
  • As long as the parameters of a particular routing protocol are followed, data will be delivered successfully from source to destination. 
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