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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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This commit is contained in:
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 MIN_DIFFERENCE (ETX_DIVISOR + ETX_DIVISOR / 2)
static void
reset(rpl_dag_t *dag)
{
@ -91,6 +93,9 @@ calculate_rank(rpl_parent_t *p, rpl_rank_t base_rank)
static rpl_parent_t *
best_parent(rpl_parent_t *p1, rpl_parent_t *p2)
{
rpl_rank_t r1, r2;
rpl_dag_t *dag;
PRINTF("RPL: Comparing parent ");
PRINT6ADDR(&p1->addr);
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);
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
for that parent. We choose the parent that has the most
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;
} else {
return p2;