diff U3 C:/igmp_patch2/igmp_original.c C:/igmp_patch2/igmp.c
--- C:/igmp_patch2/igmp_original.c	Fri Nov 16 14:31:12 2007
+++ C:/igmp_patch2/igmp.c	Sun Mar 09 20:09:03 2008
@@ -137,6 +137,17 @@
 #define igmp_dump_group_list()
 #endif /* LWIP_DEBUG */
 
+#ifndef LWIP_IGMP_RANDOM
+/* The end user can override this macro to provide his own random number routine 
+   For example to use the standard c rand() function, include the following 
+   in your lwipopts.h file: 
+      #define IGMP_RANDOM(max) ((u8_t) ((long) max * rand()/RAND_MAX))
+   The user routine should return a random u8_t ranging from 0 to max. 
+   Default to the original source, which simply used max/2:  
+*/
+#define IGMP_RANDOM(max) ((u8_t) ((max)/2))
+#endif
+
 /**
  * Start IGMP processing on interface
  *
@@ -640,9 +651,6 @@
 void
 igmp_start_timer(struct igmp_group *group, u8_t max_time)
 {
-  /**
-   * @todo Important !! this should be random 0 -> max_time. Find out how to do this
-   */
   group->timer = max_time;
 }
 
@@ -666,8 +674,15 @@
 void
 igmp_delaying_member( struct igmp_group *group, u8_t maxresp)
 {
-  if ((group->group_state == IGMP_GROUP_IDLE_MEMBER) || ((group->group_state == IGMP_GROUP_DELAYING_MEMBER) && (maxresp > group->timer))) {
-    igmp_start_timer(group, (maxresp)/2);
+  u8_t time;
+  if (   (group->group_state == IGMP_GROUP_IDLE_MEMBER) 
+      || ((group->group_state == IGMP_GROUP_DELAYING_MEMBER) && ((group->timer==0) || (maxresp > group->timer)))
+     ) {
+    time = LWIP_IGMP_RANDOM(maxresp);  /* Generate a random u8_t integer 0 to maxresp */ 
+    if (time==0) {                     	/* For now change 0 to 1 to force a send the next timer tick. */
+      time = 1;                         /* In the future, a developer can change this to send message  */
+    }                                   /* right now if time == 0 without macro breakage. */		
+    igmp_start_timer(group, time);
     group->group_state = IGMP_GROUP_DELAYING_MEMBER;
   }
 }