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Added a hysteresis when choosing a new parent: don't switch parent unless the ETX is significantly better (1.5 ETX better).

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Adam Dunkels 2011-02-13 14:14:16 +01:00
parent 48fb9dda9e
commit 3a824d0ed6
1 changed files with 13 additions and 2 deletions
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15
core/net/rpl/rpl-of0.c
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@ -60,6 +60,8 @@ rpl_of_t rpl_of0 = {
#define DEFAULT_RANK_INCREMENT DEFAULT_MIN_HOPRANKINC #define DEFAULT_RANK_INCREMENT DEFAULT_MIN_HOPRANKINC
#define MIN_DIFFERENCE (ETX_DIVISOR + ETX_DIVISOR / 2)
static void static void
reset(rpl_dag_t *dag) reset(rpl_dag_t *dag)
{ {
@ -91,6 +93,9 @@ calculate_rank(rpl_parent_t *p, rpl_rank_t base_rank)
static rpl_parent_t * static rpl_parent_t *
best_parent(rpl_parent_t *p1, rpl_parent_t *p2) best_parent(rpl_parent_t *p1, rpl_parent_t *p2)
{ {
rpl_rank_t r1, r2;
rpl_dag_t *dag;
PRINTF("RPL: Comparing parent "); PRINTF("RPL: Comparing parent ");
PRINT6ADDR(&p1->addr); PRINT6ADDR(&p1->addr);
PRINTF(" (confidence %d, rank %d) with parent ", PRINTF(" (confidence %d, rank %d) with parent ",
@ -100,11 +105,17 @@ best_parent(rpl_parent_t *p1, rpl_parent_t *p2)
p2->etx, p2->rank); p2->etx, p2->rank);
r1 = DAG_RANK(p1->rank, (rpl_dag_t *)p1->dag) * ETX_DIVISOR + p1->etx;
r2 = DAG_RANK(p2->rank, (rpl_dag_t *)p1->dag) * ETX_DIVISOR + p2->etx;
/* Compare two parents by looking both and their rank and at the ETX /* Compare two parents by looking both and their rank and at the ETX
for that parent. We choose the parent that has the most for that parent. We choose the parent that has the most
favourable combination. */ favourable combination. */
if(DAG_RANK(p1->rank, (rpl_dag_t *)p1->dag) * ETX_DIVISOR + p1->etx <
DAG_RANK(p2->rank, (rpl_dag_t *)p1->dag) * ETX_DIVISOR + p2->etx) { dag = (rpl_dag_t *)p1->dag; /* Both parents must be in the same DAG. */
if(r1 < r2 + MIN_DIFFERENCE &&
r1 > r2 - MIN_DIFFERENCE) {
return dag->preferred_parent;
} else if(r1 < r2) {
return p1; return p1;
} else { } else {
return p2; return p2;