218 lines
7.1 KiB
C
218 lines
7.1 KiB
C
/*
|
|
* Copyright (c) 2010, Swedish Institute of Computer Science.
|
|
* All rights reserved.
|
|
*
|
|
* Redistribution and use in source and binary forms, with or without
|
|
* modification, are permitted provided that the following conditions
|
|
* are met:
|
|
* 1. Redistributions of source code must retain the above copyright
|
|
* notice, this list of conditions and the following disclaimer.
|
|
* 2. Redistributions in binary form must reproduce the above copyright
|
|
* notice, this list of conditions and the following disclaimer in the
|
|
* documentation and/or other materials provided with the distribution.
|
|
* 3. Neither the name of the Institute nor the names of its contributors
|
|
* may be used to endorse or promote products derived from this software
|
|
* without specific prior written permission.
|
|
*
|
|
* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
|
|
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
* ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
|
|
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
|
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
|
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
* SUCH DAMAGE.
|
|
*
|
|
* This file is part of the Contiki operating system.
|
|
*
|
|
*/
|
|
|
|
/**
|
|
* \file
|
|
* An implementation of RPL's objective function 0, RFC6552
|
|
*
|
|
* \author Joakim Eriksson <joakime@sics.se>, Nicolas Tsiftes <nvt@sics.se>
|
|
*/
|
|
|
|
/**
|
|
* \addtogroup uip6
|
|
* @{
|
|
*/
|
|
|
|
#include "net/rpl/rpl.h"
|
|
#include "net/rpl/rpl-private.h"
|
|
#include "net/nbr-table.h"
|
|
#include "net/link-stats.h"
|
|
|
|
#define DEBUG DEBUG_NONE
|
|
#include "net/ip/uip-debug.h"
|
|
|
|
/* Constants from RFC6552. We use the default values. */
|
|
#define RANK_STRETCH 0 /* Must be in the range [0;5] */
|
|
#define RANK_FACTOR 1 /* Must be in the range [1;4] */
|
|
|
|
#define MIN_STEP_OF_RANK 1
|
|
#define MAX_STEP_OF_RANK 9
|
|
|
|
/* OF0 computes rank increase as follows:
|
|
* rank_increase = (RANK_FACTOR * STEP_OF_RANK + RANK_STRETCH) * min_hop_rank_increase
|
|
* STEP_OF_RANK is an implementation-specific scalar value in the range [1;9].
|
|
* RFC6552 provides a default value of 3 but recommends to use a dynamic link metric
|
|
* such as ETX.
|
|
* */
|
|
|
|
#define RPL_OF0_FIXED_SR 0
|
|
#define RPL_OF0_ETX_BASED_SR 1
|
|
/* Select RPL_OF0_FIXED_SR or RPL_OF0_ETX_BASED_SR */
|
|
#ifdef RPL_OF0_CONF_SR
|
|
#define RPL_OF0_SR RPL_OF0_CONF_SR
|
|
#else /* RPL_OF0_CONF_SR */
|
|
#define RPL_OF0_SR RPL_OF0_ETX_BASED_SR
|
|
#endif /* RPL_OF0_CONF_SR */
|
|
|
|
#if RPL_OF0_FIXED_SR
|
|
#define STEP_OF_RANK(p) (3)
|
|
#endif /* RPL_OF0_FIXED_SR */
|
|
|
|
#if RPL_OF0_ETX_BASED_SR
|
|
/* Numbers suggested by P. Thubert for in the 6TiSCH WG. Anything that maps ETX to
|
|
* a step between 1 and 9 works. */
|
|
#define STEP_OF_RANK(p) (((3 * parent_link_metric(p)) / LINK_STATS_ETX_DIVISOR) - 2)
|
|
#endif /* RPL_OF0_ETX_BASED_SR */
|
|
|
|
/*---------------------------------------------------------------------------*/
|
|
static void
|
|
reset(rpl_dag_t *dag)
|
|
{
|
|
PRINTF("RPL: Reset OF0\n");
|
|
}
|
|
/*---------------------------------------------------------------------------*/
|
|
static uint16_t
|
|
parent_link_metric(rpl_parent_t *p)
|
|
{
|
|
/* OF0 operates without metric container; the only metric we have is ETX */
|
|
const struct link_stats *stats = rpl_get_parent_link_stats(p);
|
|
return stats != NULL ? stats->etx : 0xffff;
|
|
}
|
|
/*---------------------------------------------------------------------------*/
|
|
static uint16_t
|
|
parent_rank_increase(rpl_parent_t *p)
|
|
{
|
|
uint16_t min_hoprankinc;
|
|
if(p == NULL || p->dag == NULL || p->dag->instance == NULL) {
|
|
return INFINITE_RANK;
|
|
}
|
|
min_hoprankinc = p->dag->instance->min_hoprankinc;
|
|
return (RANK_FACTOR * STEP_OF_RANK(p) + RANK_STRETCH) * min_hoprankinc;
|
|
}
|
|
/*---------------------------------------------------------------------------*/
|
|
static uint16_t
|
|
parent_path_cost(rpl_parent_t *p)
|
|
{
|
|
if(p == NULL) {
|
|
return 0xffff;
|
|
}
|
|
/* path cost upper bound: 0xffff */
|
|
return MIN((uint32_t)p->rank + parent_link_metric(p), 0xffff);
|
|
}
|
|
/*---------------------------------------------------------------------------*/
|
|
static rpl_rank_t
|
|
rank_via_parent(rpl_parent_t *p)
|
|
{
|
|
if(p == NULL) {
|
|
return INFINITE_RANK;
|
|
} else {
|
|
return MIN((uint32_t)p->rank + parent_rank_increase(p), INFINITE_RANK);
|
|
}
|
|
}
|
|
/*---------------------------------------------------------------------------*/
|
|
static int
|
|
parent_is_acceptable(rpl_parent_t *p)
|
|
{
|
|
return STEP_OF_RANK(p) >= MIN_STEP_OF_RANK
|
|
&& STEP_OF_RANK(p) <= MAX_STEP_OF_RANK;
|
|
}
|
|
/*---------------------------------------------------------------------------*/
|
|
static rpl_parent_t *
|
|
best_parent(rpl_parent_t *p1, rpl_parent_t *p2)
|
|
{
|
|
rpl_dag_t *dag;
|
|
uint16_t p1_cost;
|
|
uint16_t p2_cost;
|
|
int p1_is_acceptable;
|
|
int p2_is_acceptable;
|
|
|
|
if(p1 == NULL || p2 == NULL) {
|
|
/* Return non-null parent if any */
|
|
return p1 == NULL ? p2 : p1;
|
|
}
|
|
|
|
p1_is_acceptable = parent_is_acceptable(p1);
|
|
p2_is_acceptable = parent_is_acceptable(p2);
|
|
/* Is only one parent is acceptable, select it. If both are acceptable, or
|
|
* both non-acceptable, proceed to traditional parent comparison. This is a
|
|
* slight departure from the standard but allows to keep connectivity even
|
|
* all neighbors appear to have a bad link. */
|
|
if(p1_is_acceptable != p2_is_acceptable) {
|
|
return p1_is_acceptable ? p1 : p2;
|
|
}
|
|
|
|
dag = p1->dag; /* Both parents are in the same DAG. */
|
|
p1_cost = parent_path_cost(p1);
|
|
p2_cost = parent_path_cost(p2);
|
|
|
|
/* Paths costs coarse-grained (multiple of min_hoprankinc), we operate without hysteresis */
|
|
if(p1_cost != p2_cost) {
|
|
/* Pick parent with lowest path cost */
|
|
return p1_cost < p2_cost ? p1 : p2;
|
|
} else {
|
|
/* We have a tie! */
|
|
/* Stik to current preferred parent if possible */
|
|
if(p1 == dag->preferred_parent || p2 == dag->preferred_parent) {
|
|
return dag->preferred_parent;
|
|
}
|
|
/* None of the nodes is the current preferred parent,
|
|
* choose parent with best link metric */
|
|
return parent_link_metric(p1) < parent_link_metric(p2) ? p1 : p2;
|
|
}
|
|
}
|
|
/*---------------------------------------------------------------------------*/
|
|
static rpl_dag_t *
|
|
best_dag(rpl_dag_t *d1, rpl_dag_t *d2)
|
|
{
|
|
if(d1->grounded != d2->grounded) {
|
|
return d1->grounded ? d1 : d2;
|
|
}
|
|
|
|
if(d1->preference != d2->preference) {
|
|
return d1->preference > d2->preference ? d1 : d2;
|
|
}
|
|
|
|
return d1->rank < d2->rank ? d1 : d2;
|
|
}
|
|
/*---------------------------------------------------------------------------*/
|
|
static void
|
|
update_metric_container(rpl_instance_t *instance)
|
|
{
|
|
instance->mc.type = RPL_DAG_MC_NONE;
|
|
}
|
|
/*---------------------------------------------------------------------------*/
|
|
rpl_of_t rpl_of0 = {
|
|
reset,
|
|
#if RPL_WITH_DAO_ACK
|
|
NULL,
|
|
#endif
|
|
parent_link_metric,
|
|
parent_path_cost,
|
|
rank_via_parent,
|
|
best_parent,
|
|
best_dag,
|
|
update_metric_container,
|
|
RPL_OCP_OF0
|
|
};
|
|
|
|
/** @}*/
|