This chapter covers the following topics:
Data Link Layer Support for Multicast—Describes three methods to send multicasts to ports where the traffic is wanted and to hide multicasts from other hosts.
Understanding IGMP—Describes the features of IGMPv1, IGMPv2, and IGMPv3 and how to determine which IGMP version is running on a router.
Configuring IGMP—Describes enabling IGMP groups and configuring IGMP snooping.
Because not everyone on a network wants to receive the traffic from a multicast source, routers must have some means of forwarding traffic to only the destinations that want to receive it. This chapter covers IP multicast and some of the protocols used to forward multicast packets. You will learn the basic features and operation of IGMP and how to configure IGMP groups and IGMP snooping.
The purpose of the "Do I Know This Already?" quiz is to help you decide which parts of this chapter to use. If you already intend to read the entire chapter, you do not necessarily need to answer these questions.
The 11-question quiz, derived from the major sections in the "Foundation Topics" portion of the chapter, helps you determine how to spend your limited study time.
Table 18-1 outlines the major topics discussed in this chapter and the corresponding quiz questions.
|Foundation Topics Section||Questions Covered in This Section||Score|
|Data Link Layer Support for Multicast||1–4|
The goal of self-assessment is to gauge your mastery of the topics in this chapter. If you do not know the answer to a question or are only partially sure of the answer, you should mark the question wrong for purposes of the self-assessment. Giving yourself credit for an answer you correctly guessed skews your results and might provide you with a false sense of security.
|1.||Layer 2 switches build a MAC table by observing which of the following?
|2.||IGMP stands for which of the following?
|3.||Which of the following is not a method of associating multicasts with ports?
|4.||Which of the following are differences between IGMP Snooping and CGMP?
|5.||What is the primary issue with IGMP version 1?
|6.||Which of the following are advantages of IGMP v2 over IGMPv1?
|7.||IGMPv1 does not have a mechanism to allow a host to leave a group when it is no longer interested in the content of that group. Which of the following is an advantage of IGMPv3 over version 2?
|8.||What command displays the current IGMP version used on a port?
|9.||What command is used to manually join a router to a group?
|10.||How do you turn on IGMP Snooping?
|11.||Which of the following commands displays the multicast groups used?
You can find the answers to the "Do I Know This Already?" quiz in Appendix A, "Answers to Chapter 'Do I Know This Already?' Quizzes and Q&A Sections." The suggested choices for your next step are as follows: