Upon completion you will be able to: Know the purpose of IGMP, know the types of IGMP messages, understand how a member joins a group and leaves a group, understand membership monitoring, understand how an IGMP message is encapsulated, understand the interactions of the modules of an IGMP package. | Chapter 10 Internet Group Management Protocol (IGMP) CONTENTS GROUP MANAGEMENT IGMP MESSAGES IGMP OPERATION ENCAPSULATION IGMP PACKAGE Figure 10-1 Position of IGMP in the network layer GROUP MANAGEMENT IGMP MESSAGES IGMP is a group management protocol. It helps a multicast router create and update a list of loyal members related to each router interface. Figure 10-2 IGMP message types Figure 10-3 IGMP message format IGMP OPERATION Figure 10-4 IGMP operation Figure 10-5 Membership report In IGMP, a membership report is sent twice, one after the other. Figure 10-6 Leave report The general query message does not define a particular group. Figure 10-7 General query message Example 1 Imagine there are three hosts in a network as shown in Figure (next slide). Imagine there are three hosts in a network as shown in Figure (next slide). A query message was received at time 0; the random delay time (in tenths of seconds) for each group is shown next to the group address. Show the sequence of report messages. Figure 10-8 Example 1 Solution The events occur in this sequence: Time 12: The timer for in host A expires and a membership report is sent, which is received by the router and every host including host B which cancels its timer for . Time 30: The timer for in host A expires and a membership report is sent, which is received by the router and every host including host C which cancels its timer for . Solution (Continued) Time 50: The timer for in host C expires and a membership report is sent, which is received by the router and every host. Time 70: The timer for in host A expires and a membership report is sent, which is received by the router and every host including host A which cancels its timer for . Note that if each host had sent a report for every group in its list, there would have been seven reports; with this strategy only four reports are sent. ENCAPSULATION Figure 10-9 Encapsulation of IGMP packet The IP packet that carries an IGMP packet has a value of 2 in its protocol field. The IP packet that carries an IGMP packet has a value of 1 in its TTL field. Figure 10-10 Mapping class D to Ethernet physical address Figure 10-11 Tunneling IGMP PACKAGE Figure 10-12 IGMP package Figure 10-13 State: Free, Delaying, Idle Reference Count: Number of processes interested Group table | Chapter 10 Internet Group Management Protocol (IGMP) CONTENTS GROUP MANAGEMENT IGMP MESSAGES IGMP OPERATION ENCAPSULATION IGMP PACKAGE Figure 10-1 Position of IGMP in the network layer GROUP MANAGEMENT IGMP MESSAGES IGMP is a group management protocol. It helps a multicast router create and update a list of loyal members related to each router interface. Figure 10-2 IGMP message types Figure 10-3 IGMP message format IGMP OPERATION Figure 10-4 IGMP operation Figure 10-5 Membership report In IGMP, a membership report is sent twice, one after the other. Figure 10-6 Leave report The general query message does not define a particular group. Figure 10-7 General query message Example 1 Imagine there are three hosts in a network as shown in Figure (next slide). Imagine there are three hosts in a network as shown in Figure (next slide). A query message was received at time 0; the random delay time (in tenths of seconds) for each group is shown next to the group
