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C/C++ Source or Header  |  1997-04-27  |  851 b   |  28 lines
  1. /*
  2.  * Internet Group Management Protocol (IGMP) definitions.
  3.  *
  4.  * Written by Steve Deering, Stanford, May 1988.
  5.  *
  6.  * MULTICAST 1.1
  7.  */
  8.  
  9. /*
  10.  * IGMP packet format.
  11.  */
  12. struct igmp {
  13.     u_char        igmp_type;        /* version & type of IGMP message  */
  14.     u_char        igmp_code;        /* unused, should be zero          */
  15.     u_short        igmp_cksum;        /* IP-style checksum               */
  16.     struct in_addr    igmp_group;    /* group address being reported    */
  17. };                                /*  (zero for queries)             */
  18.  
  19. #define IGMP_MINLEN             8
  20.  
  21. #define IGMP_HOST_MEMBERSHIP_QUERY    0x11    /* message types, incl. version */
  22. #define IGMP_HOST_MEMBERSHIP_REPORT    0x12
  23. #define IGMP_DVMRP                    0x13    /* for experimental multicast   */
  24.                                             /*  routing protocol            */
  25.  
  26. #define IGMP_MAX_HOST_REPORT_DELAY    10        /* max delay for response to    */
  27.                                             /*  query (in seconds)          */
  28.