201 lines
6.6 KiB
C
201 lines
6.6 KiB
C
/*
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* Copyright (c) 2010, Swedish Institute of Computer Science.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the Institute nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* This file is part of the Contiki operating system.
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*
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*/
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/**
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* \addtogroup rpl-lite
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* @{
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*
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* \file
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* An implementation of RPL's objective function 0, RFC6552
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*
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* \author Joakim Eriksson <joakime@sics.se>, Nicolas Tsiftes <nvt@sics.se>
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* Simon Duquennoy <simon.duquennoy@inria.fr>
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*/
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#include "net/routing/rpl-lite/rpl.h"
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#include "net/nbr-table.h"
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#include "net/link-stats.h"
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/* Log configuration */
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#include "sys/log.h"
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#define LOG_MODULE "RPL"
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#define LOG_LEVEL LOG_LEVEL_RPL
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/* Constants from RFC6552. We use the default values. */
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#define RANK_STRETCH 0 /* Must be in the range [0;5] */
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#define RANK_FACTOR 1 /* Must be in the range [1;4] */
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#define MIN_STEP_OF_RANK 1
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#define MAX_STEP_OF_RANK 9
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/* OF0 computes rank increase as follows:
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* rank_increase = (RANK_FACTOR * STEP_OF_RANK + RANK_STRETCH) * min_hop_rank_increase
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* STEP_OF_RANK is an implementation-specific scalar value in the range [1;9].
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* RFC6552 provides a default value of 3 but recommends to use a dynamic link metric
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* such as ETX.
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* */
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#define RPL_OF0_FIXED_SR 0
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#define RPL_OF0_ETX_BASED_SR 1
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/* Select RPL_OF0_FIXED_SR or RPL_OF0_ETX_BASED_SR */
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#ifdef RPL_OF0_CONF_SR
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#define RPL_OF0_SR RPL_OF0_CONF_SR
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#else /* RPL_OF0_CONF_SR */
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#define RPL_OF0_SR RPL_OF0_ETX_BASED_SR
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#endif /* RPL_OF0_CONF_SR */
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#if RPL_OF0_FIXED_SR
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#define STEP_OF_RANK(nbr) (3)
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#endif /* RPL_OF0_FIXED_SR */
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#if RPL_OF0_ETX_BASED_SR
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/* Numbers suggested by P. Thubert for in the 6TiSCH WG. Anything that maps ETX to
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* a step between 1 and 9 works. */
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#define STEP_OF_RANK(nbr) (((3 * nbr_link_metric(nbr)) / LINK_STATS_ETX_DIVISOR) - 2)
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#endif /* RPL_OF0_ETX_BASED_SR */
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/*---------------------------------------------------------------------------*/
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static void
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reset(void)
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{
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LOG_INFO("reset OF0\n");
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}
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/*---------------------------------------------------------------------------*/
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static uint16_t
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nbr_link_metric(rpl_nbr_t *nbr)
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{
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/* OF0 operates without metric container; the only metric we have is ETX */
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const struct link_stats *stats = rpl_neighbor_get_link_stats(nbr);
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return stats != NULL ? stats->etx : 0xffff;
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}
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/*---------------------------------------------------------------------------*/
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static uint16_t
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nbr_rank_increase(rpl_nbr_t *nbr)
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{
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uint16_t min_hoprankinc;
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if(nbr == NULL) {
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return RPL_INFINITE_RANK;
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}
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min_hoprankinc = curr_instance.min_hoprankinc;
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return (RANK_FACTOR * STEP_OF_RANK(nbr) + RANK_STRETCH) * min_hoprankinc;
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}
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/*---------------------------------------------------------------------------*/
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static uint16_t
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nbr_path_cost(rpl_nbr_t *nbr)
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{
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if(nbr == NULL) {
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return 0xffff;
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}
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/* path cost upper bound: 0xffff */
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return MIN((uint32_t)nbr->rank + nbr_link_metric(nbr), 0xffff);
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}
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/*---------------------------------------------------------------------------*/
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static rpl_rank_t
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rank_via_nbr(rpl_nbr_t *nbr)
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{
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if(nbr == NULL) {
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return RPL_INFINITE_RANK;
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} else {
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return MIN((uint32_t)nbr->rank + nbr_rank_increase(nbr), RPL_INFINITE_RANK);
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}
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}
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/*---------------------------------------------------------------------------*/
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static int
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nbr_has_usable_link(rpl_nbr_t *nbr)
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{
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return 1;
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}
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/*---------------------------------------------------------------------------*/
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static int
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nbr_is_acceptable_parent(rpl_nbr_t *nbr)
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{
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return STEP_OF_RANK(nbr) >= MIN_STEP_OF_RANK
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&& STEP_OF_RANK(nbr) <= MAX_STEP_OF_RANK;
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}
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/*---------------------------------------------------------------------------*/
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static rpl_nbr_t *
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best_parent(rpl_nbr_t *nbr1, rpl_nbr_t *nbr2)
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{
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uint16_t nbr1_cost;
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uint16_t nbr2_cost;
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int nbr1_is_acceptable;
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int nbr2_is_acceptable;
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nbr1_is_acceptable = nbr1 != NULL && nbr_is_acceptable_parent(nbr1);
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nbr2_is_acceptable = nbr2 != NULL && nbr_is_acceptable_parent(nbr2);
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if(!nbr1_is_acceptable) {
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return nbr2_is_acceptable ? nbr2 : NULL;
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}
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if(!nbr2_is_acceptable) {
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return nbr1_is_acceptable ? nbr1 : NULL;
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}
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nbr1_cost = nbr_path_cost(nbr1);
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nbr2_cost = nbr_path_cost(nbr2);
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/* Paths costs coarse-grained (multiple of min_hoprankinc), we operate without hysteresis */
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if(nbr1_cost != nbr2_cost) {
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/* Pick nbr with lowest path cost */
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return nbr1_cost < nbr2_cost ? nbr1 : nbr2;
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} else {
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/* We have a tie! */
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/* Stik to current preferred parent if possible */
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if(nbr1 == curr_instance.dag.preferred_parent || nbr2 == curr_instance.dag.preferred_parent) {
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return curr_instance.dag.preferred_parent;
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}
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/* None of the nodes is the current preferred parent,
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* choose nbr with best link metric */
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return nbr_link_metric(nbr1) < nbr_link_metric(nbr2) ? nbr1 : nbr2;
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}
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}
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/*---------------------------------------------------------------------------*/
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static void
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update_metric_container(void)
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{
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curr_instance.mc.type = RPL_DAG_MC_NONE;
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}
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/*---------------------------------------------------------------------------*/
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rpl_of_t rpl_of0 = {
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reset,
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nbr_link_metric,
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nbr_has_usable_link,
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nbr_is_acceptable_parent,
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nbr_path_cost,
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rank_via_nbr,
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best_parent,
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update_metric_container,
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RPL_OCP_OF0
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};
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/** @}*/
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