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rpl-of0.c
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1/*
2 * Copyright (c) 2010, Swedish Institute of Computer Science.
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 3. Neither the name of the Institute nor the names of its contributors
14 * may be used to endorse or promote products derived from this software
15 * without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 *
29 * This file is part of the Contiki operating system.
30 *
31 */
32
33/**
34 * \addtogroup rpl-lite
35 * @{
36 *
37 * \file
38 * An implementation of RPL's objective function 0, RFC6552
39 *
40 * \author Joakim Eriksson <joakime@sics.se>, Nicolas Tsiftes <nvt@sics.se>
41 * Simon Duquennoy <simon.duquennoy@inria.fr>
42 */
43
44#include "net/routing/rpl-lite/rpl.h"
45#include "net/nbr-table.h"
46#include "net/link-stats.h"
47
48/* Log configuration */
49#include "sys/log.h"
50#define LOG_MODULE "RPL"
51#define LOG_LEVEL LOG_LEVEL_RPL
52
53/* Constants from RFC6552. We use the default values. */
54#define RANK_STRETCH 0 /* Must be in the range [0;5] */
55#define RANK_FACTOR 1 /* Must be in the range [1;4] */
56
57#define MIN_STEP_OF_RANK 1
58#define MAX_STEP_OF_RANK 9
59
60/* OF0 computes rank increase as follows:
61 * rank_increase = (RANK_FACTOR * STEP_OF_RANK + RANK_STRETCH) * min_hop_rank_increase
62 * STEP_OF_RANK is an implementation-specific scalar value in the range [1;9].
63 * RFC6552 provides a default value of 3 but recommends to use a dynamic link metric
64 * such as ETX.
65 * */
66
67#define RPL_OF0_FIXED_SR 0
68#define RPL_OF0_ETX_BASED_SR 1
69/* Select RPL_OF0_FIXED_SR or RPL_OF0_ETX_BASED_SR */
70#ifdef RPL_OF0_CONF_SR
71#define RPL_OF0_SR RPL_OF0_CONF_SR
72#else /* RPL_OF0_CONF_SR */
73#define RPL_OF0_SR RPL_OF0_ETX_BASED_SR
74#endif /* RPL_OF0_CONF_SR */
75
76#if RPL_OF0_FIXED_SR
77#define STEP_OF_RANK(nbr) (3)
78#endif /* RPL_OF0_FIXED_SR */
79
80#if RPL_OF0_ETX_BASED_SR
81/* Numbers suggested by P. Thubert for in the 6TiSCH WG. Anything that maps ETX to
82 * a step between 1 and 9 works. */
83#define STEP_OF_RANK(nbr) (((3 * nbr_link_metric(nbr)) / LINK_STATS_ETX_DIVISOR) - 2)
84#endif /* RPL_OF0_ETX_BASED_SR */
85
86/*---------------------------------------------------------------------------*/
87static void
88reset(void)
89{
90 LOG_INFO("reset OF0\n");
91}
92/*---------------------------------------------------------------------------*/
93static uint16_t
94nbr_link_metric(rpl_nbr_t *nbr)
95{
96 /* OF0 operates without metric container; the only metric we have is ETX */
97 const struct link_stats *stats = rpl_neighbor_get_link_stats(nbr);
98 return stats != NULL ? stats->etx : 0xffff;
99}
100/*---------------------------------------------------------------------------*/
101static uint16_t
102nbr_rank_increase(rpl_nbr_t *nbr)
103{
104 uint16_t min_hoprankinc;
105 if(nbr == NULL) {
106 return RPL_INFINITE_RANK;
107 }
108 min_hoprankinc = curr_instance.min_hoprankinc;
109 return (RANK_FACTOR * STEP_OF_RANK(nbr) + RANK_STRETCH) * min_hoprankinc;
110}
111/*---------------------------------------------------------------------------*/
112static uint16_t
113nbr_path_cost(rpl_nbr_t *nbr)
114{
115 if(nbr == NULL) {
116 return 0xffff;
117 }
118 /* path cost upper bound: 0xffff */
119 return MIN((uint32_t)nbr->rank + nbr_link_metric(nbr), 0xffff);
120}
121/*---------------------------------------------------------------------------*/
122static rpl_rank_t
123rank_via_nbr(rpl_nbr_t *nbr)
124{
125 if(nbr == NULL) {
126 return RPL_INFINITE_RANK;
127 } else {
128 return MIN((uint32_t)nbr->rank + nbr_rank_increase(nbr), RPL_INFINITE_RANK);
129 }
130}
131/*---------------------------------------------------------------------------*/
132static int
133nbr_has_usable_link(rpl_nbr_t *nbr)
134{
135 return 1;
136}
137/*---------------------------------------------------------------------------*/
138static int
139nbr_is_acceptable_parent(rpl_nbr_t *nbr)
140{
141 return STEP_OF_RANK(nbr) >= MIN_STEP_OF_RANK
142 && STEP_OF_RANK(nbr) <= MAX_STEP_OF_RANK;
143}
144/*---------------------------------------------------------------------------*/
145static rpl_nbr_t *
146best_parent(rpl_nbr_t *nbr1, rpl_nbr_t *nbr2)
147{
148 uint16_t nbr1_cost;
149 uint16_t nbr2_cost;
150 int nbr1_is_acceptable;
151 int nbr2_is_acceptable;
152
153 nbr1_is_acceptable = nbr1 != NULL && nbr_is_acceptable_parent(nbr1);
154 nbr2_is_acceptable = nbr2 != NULL && nbr_is_acceptable_parent(nbr2);
155
156 if(!nbr1_is_acceptable) {
157 return nbr2_is_acceptable ? nbr2 : NULL;
158 }
159 if(!nbr2_is_acceptable) {
160 return nbr1_is_acceptable ? nbr1 : NULL;
161 }
162
163 nbr1_cost = nbr_path_cost(nbr1);
164 nbr2_cost = nbr_path_cost(nbr2);
165
166 /* Paths costs coarse-grained (multiple of min_hoprankinc), we operate without hysteresis */
167 if(nbr1_cost != nbr2_cost) {
168 /* Pick nbr with lowest path cost */
169 return nbr1_cost < nbr2_cost ? nbr1 : nbr2;
170 } else {
171 /* We have a tie! */
172 /* Stik to current preferred parent if possible */
173 if(nbr1 == curr_instance.dag.preferred_parent || nbr2 == curr_instance.dag.preferred_parent) {
174 return curr_instance.dag.preferred_parent;
175 }
176 /* None of the nodes is the current preferred parent,
177 * choose nbr with best link metric */
178 return nbr_link_metric(nbr1) < nbr_link_metric(nbr2) ? nbr1 : nbr2;
179 }
180}
181/*---------------------------------------------------------------------------*/
182static void
183update_metric_container(void)
184{
185 curr_instance.mc.type = RPL_DAG_MC_NONE;
186}
187/*---------------------------------------------------------------------------*/
188rpl_of_t rpl_of0 = {
189 reset,
190 nbr_link_metric,
191 nbr_has_usable_link,
192 nbr_is_acceptable_parent,
193 nbr_path_cost,
194 rank_via_nbr,
195 best_parent,
196 update_metric_container,
197 RPL_OCP_OF0
198};
199
200/** @}*/
const struct link_stats * rpl_neighbor_get_link_stats(rpl_nbr_t *nbr)
Returns a neighbor's link statistics.
Header file for the logging system.
All information related to a RPL neighbor.
Definition rpl-types.h:136
API for RPL objective functions (OF)
Definition rpl.h:204
static uip_ds6_nbr_t * nbr
Pointer to llao option in uip_buf.
Definition uip-nd6.c:106