# 5.0.1.2 Stand By Me Instructions Answers

## 5.0.1.2 Stand By Me (Instructor Version – Optional Lab)

Instructor Note: Red font color or gray highlights indicate text that appears in the instructor copy only. Optional activities are designed to enhance understanding and/or to provide additional practice.

### Objective

Describe the role of unicast, broadcast, and multicast in a switched network.

Students are given three scenarios where activity-based numbers will need to be recorded. At the end of the activity, students will answer questions about how this introductory process relates to sending and receiving messages on a switch.

 501A 501B 501C 501D 501E 502A 502B 502C 502D 502E 503A 503B 503C 503D 503E 504A 504B 504C 504D 504E 505A 505B 505C 505D 505E

### Scenario

When you arrived to class today, you were given a number by your instructor to use for this introductory class activity.

Once class begins, your instructor will ask certain students with specific numbers to stand. Your job is to record the standing students’ numbers for each scenario.

Scenario 1

Students with numbers starting with the number 5 should stand. Record the numbers of the standing students. All students will stand and all the numbers will be recorded by each student.

Scenario 2

Students with numbers ending in B should stand. Record the numbers of the standing students. More than one student should stand, but not all students will stand. All numbers of standing students will be recorded by all students.

Scenario 3

Students with the number 504C should stand. Record the number of the standing student. Only one student will stand and all students will record that number.

At the end of this activity, divide into small groups and record answers to the Reflection questions on the PDF for this activity.

### Reflection

1. Why do you think you were asked to record the students’ numbers when and as requested?
_____________________________________________________
Recording was necessary to see how groups are formed in networking. Recording helps you to identify to which group the students belong. Recording helps to keep a list of who has been seen in certain groups.

2. What is the significance of the number 5 in this activity? How many people were identified with this number?
_____________________________________________________
All students received a number beginning with 5, as this indicates a full group of students. This is similar to a network broadcast situation.

3. What is the significance of the letter C in this activity? How many people were identified with this number?
_____________________________________________________
The letter C allows a smaller grouping of students to be identified – very similar to a multicast situation.

4. Why did only one person stand for 504C?
_____________________________________________________
This number is unique to the class – therefore, it indicates a unicast form of network transmission.

5. How do you think this activity represents data travelling on local area networks?
_____________________________________________________
When a switch first sees hosts on its network, it will record responses from those hosts in respect to unicasts, multicasts, and broadcasts (flooding). That is how it builds its MAC address table. Once the MAC addresses have been recorded by the switch, specific types of traffic can be switched (unicasts, broadcasts, and multicasts). The significance of the numbers illustrates unicast, multicast, and broadcast selection methods.

Save your work and be prepared to share it with another student or the entire class. (Instructor choice)

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

• Switches record MAC addresses, just as the numbers were recorded during this introductory activity.
• LAN switch unicasts can be sent to and/or received by hosts.
• LAN switch multicasts can be sent to and/or received by hosts.
• LAN broadcasts can be sent to and/or received by hosts.

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