Nội dung

Chapter 10 Internet Group Management Protocol (IGMP) McGraw-Hill ©The McGraw-Hill Companies, Inc., 2000 CONTENTS • GROUP MANAGEMENT • IGMP MESSAGES • IGMP OPERATION • ENCAPSULATION • IGMP PACKAGE McGraw-Hill ©The McGraw-Hill Companies, Inc., 2000 Figure 10-1 Position of IGMP in the network layer McGraw-Hill ©The McGraw-Hill Companies, Inc., 2000 10.1 GROUP MANAGEMENT McGraw-Hill ©The McGraw-Hill Companies, Inc., 2000 10.2 IGMP MESSAGES McGraw-Hill ©The McGraw-Hill Companies, Inc., 2000 IGMP is a group management protocol. It helps a multicast router create and update a list of loyal members related to each router interface. McGraw-Hill ©The McGraw-Hill Companies, Inc., 2000 Figure 10-2 IGMP message types McGraw-Hill ©The McGraw-Hill Companies, Inc., 2000 Figure 10-3 IGMP message format McGraw-Hill ©The McGraw-Hill Companies, Inc., 2000 10.3 IGMP OPERATION McGraw-Hill ©The McGraw-Hill Companies, Inc., 2000 Figure 10-4 IGMP operation McGraw-Hill ©The McGraw-Hill Companies, Inc., 2000 Figure 10-5 Membership report McGraw-Hill ©The McGraw-Hill Companies, Inc., 2000 In IGMP, a membership report is sent twice, one after the other. McGraw-Hill ©The McGraw-Hill Companies, Inc., 2000 Figure 10-6 McGraw-Hill Leave report ©The McGraw-Hill Companies, Inc., 2000 The general query message does not define a particular group. McGraw-Hill ©The McGraw-Hill Companies, Inc., 2000 Figure 10-7 General query message McGraw-Hill ©The McGraw-Hill Companies, Inc., 2000 Example 1 Imagine there are three hosts in a network as shown in Figure 10.8 (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. McGraw-Hill ©The McGraw-Hill Companies, Inc., 2000 Figure 10-8 McGraw-Hill Example 1 ©The McGraw-Hill Companies, Inc., 2000 Solution The events occur in this sequence: Time 12: The timer for 228.42.0.0 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 228.42.0.0. Time 30: The timer for 225.14.0.0 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 225.14.0.0. McGraw-Hill ©The McGraw-Hill Companies, Inc., 2000 Solution (Continued) Time 50: The timer for 251.70.0.0 in host C expires and a membership report is sent, which is received by the router and every host. Time 70: The timer for 230.43.0.0 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 230.43.0.0. 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. McGraw-Hill ©The McGraw-Hill Companies, Inc., 2000 10.4 ENCAPSULATION McGraw-Hill ©The McGraw-Hill Companies, Inc., 2000 Figure 10-9 Encapsulation of IGMP packet McGraw-Hill ©The McGraw-Hill Companies, Inc., 2000 The IP packet that carries an IGMP packet has a value of 2 in its protocol field. McGraw-Hill ©The McGraw-Hill Companies, Inc., 2000 The IP packet that carries an IGMP packet has a value of 1 in its TTL field. McGraw-Hill ©The McGraw-Hill Companies, Inc., 2000 Figure 10-10 Mapping class D to Ethernet physical address McGraw-Hill ©The McGraw-Hill Companies, Inc., 2000 Figure 10-11 McGraw-Hill Tunneling ©The McGraw-Hill Companies, Inc., 2000 10.5 IGMP PACKAGE McGraw-Hill ©The McGraw-Hill Companies, Inc., 2000 Figure 10-12 IGMP package McGraw-Hill ©The McGraw-Hill Companies, Inc., 2000 Figure 10-13 Group table State: Free, Delaying, Idle Reference Count: Number of processes interested McGraw-Hill ©The McGraw-Hill Companies, Inc., 2000