Chapter 13

Team-Fly     TCP/IP Illustrated, Volume 2: The Implementation By Gary R. Wright, W. Richard Stevens Table of Contents Appendix A.  Solutions to Selected Exercises Chapter 13 13.1 Responding to an IGMP query from the loopback interface is unnecessary since the local host is the only system on the loopback network and it already knows its membership status. 13.2 max_linkhdr+sizeof(struct ip)+IGMP_MINLEN=16+20+8=44<100 13.3 The primary reason for the random delay in reporting memberships is to minimize (ideally to 1) the number of reports that appear on a multicast network. A point-to-point network consists only of two interfaces, so the delay is not necessary to minimize the response to the query. One interface (presumably a multicast router) generates the query, and the other interface responds. There is another reason not to flood the interface's output queue with all the membership reports. The output queue may have a packet or byte limit that could be exceeded by many IGMP membership reports. For example, in the SLIP driver, if the output queue is full or the device is too busy, the entire queue of pending packets is discarded (Figure 5.17). Team-Fly     Top