contiki/core/net/rpl/rpl-mrhof.c

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/**
* \addtogroup uip6
* @{
*/
/*
* 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
* The Minimum Rank with Hysteresis Objective Function (MRHOF)
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*
* This implementation uses the estimated number of
* transmissions (ETX) as the additive routing metric,
* and also provides stubs for the energy metric.
*
* \author Joakim Eriksson <joakime@sics.se>, Nicolas Tsiftes <nvt@sics.se>
*/
#include "net/rpl/rpl-private.h"
#include "net/nbr-table.h"
#define DEBUG DEBUG_NONE
#include "net/uip-debug.h"
static void reset(rpl_dag_t *);
static void neighbor_link_callback(rpl_parent_t *, int, int);
static rpl_parent_t *best_parent(rpl_parent_t *, rpl_parent_t *);
static rpl_dag_t *best_dag(rpl_dag_t *, rpl_dag_t *);
static rpl_rank_t calculate_rank(rpl_parent_t *, rpl_rank_t);
static void update_metric_container(rpl_instance_t *);
rpl_of_t rpl_mrhof = {
reset,
neighbor_link_callback,
best_parent,
best_dag,
calculate_rank,
update_metric_container,
1
};
/* Constants for the ETX moving average */
#define ETX_SCALE 100
#define ETX_ALPHA 90
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/* Reject parents that have a higher link metric than the following. */
#define MAX_LINK_METRIC 10
/* Reject parents that have a higher path cost than the following. */
#define MAX_PATH_COST 100
/*
* The rank must differ more than 1/PARENT_SWITCH_THRESHOLD_DIV in order
* to switch preferred parent.
*/
#define PARENT_SWITCH_THRESHOLD_DIV 2
typedef uint16_t rpl_path_metric_t;
static rpl_path_metric_t
calculate_path_metric(rpl_parent_t *p)
{
if(p == NULL) {
return MAX_PATH_COST * RPL_DAG_MC_ETX_DIVISOR;
}
#if RPL_DAG_MC == RPL_DAG_MC_NONE
return p->rank + (uint16_t)p->link_metric;
#elif RPL_DAG_MC == RPL_DAG_MC_ETX
return p->mc.obj.etx + (uint16_t)p->link_metric;
#elif RPL_DAG_MC == RPL_DAG_MC_ENERGY
return p->mc.obj.energy.energy_est + (uint16_t)p->link_metric;
#else
#error "Unsupported RPL_DAG_MC configured. See rpl.h."
#endif /* RPL_DAG_MC */
}
static void
reset(rpl_dag_t *sag)
{
PRINTF("RPL: Reset MRHOF\n");
}
static void
neighbor_link_callback(rpl_parent_t *p, int status, int numtx)
{
uint16_t recorded_etx = p->link_metric;
uint16_t packet_etx = numtx * RPL_DAG_MC_ETX_DIVISOR;
uint16_t new_etx;
/* Do not penalize the ETX when collisions or transmission errors occur. */
if(status == MAC_TX_OK || status == MAC_TX_NOACK) {
if(status == MAC_TX_NOACK) {
packet_etx = MAX_LINK_METRIC * RPL_DAG_MC_ETX_DIVISOR;
}
new_etx = ((uint32_t)recorded_etx * ETX_ALPHA +
(uint32_t)packet_etx * (ETX_SCALE - ETX_ALPHA)) / ETX_SCALE;
PRINTF("RPL: ETX changed from %u to %u (packet ETX = %u)\n",
(unsigned)(recorded_etx / RPL_DAG_MC_ETX_DIVISOR),
(unsigned)(new_etx / RPL_DAG_MC_ETX_DIVISOR),
(unsigned)(packet_etx / RPL_DAG_MC_ETX_DIVISOR));
p->link_metric = new_etx;
}
}
static rpl_rank_t
calculate_rank(rpl_parent_t *p, rpl_rank_t base_rank)
{
rpl_rank_t new_rank;
rpl_rank_t rank_increase;
if(p == NULL) {
if(base_rank == 0) {
return INFINITE_RANK;
}
rank_increase = RPL_INIT_LINK_METRIC * RPL_DAG_MC_ETX_DIVISOR;
} else {
rank_increase = p->link_metric;
if(base_rank == 0) {
base_rank = p->rank;
}
}
if(INFINITE_RANK - base_rank < rank_increase) {
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/* Reached the maximum rank. */
new_rank = INFINITE_RANK;
} else {
/* Calculate the rank based on the new rank information from DIO or
stored otherwise. */
new_rank = base_rank + rank_increase;
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}
return new_rank;
}
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 rpl_parent_t *
best_parent(rpl_parent_t *p1, rpl_parent_t *p2)
{
rpl_dag_t *dag;
rpl_path_metric_t min_diff;
rpl_path_metric_t p1_metric;
rpl_path_metric_t p2_metric;
dag = p1->dag; /* Both parents are in the same DAG. */
min_diff = RPL_DAG_MC_ETX_DIVISOR /
PARENT_SWITCH_THRESHOLD_DIV;
p1_metric = calculate_path_metric(p1);
p2_metric = calculate_path_metric(p2);
/* Maintain stability of the preferred parent in case of similar ranks. */
if(p1 == dag->preferred_parent || p2 == dag->preferred_parent) {
if(p1_metric < p2_metric + min_diff &&
p1_metric > p2_metric - min_diff) {
PRINTF("RPL: MRHOF hysteresis: %u <= %u <= %u\n",
p2_metric - min_diff,
p1_metric,
p2_metric + min_diff);
return dag->preferred_parent;
}
}
return p1_metric < p2_metric ? p1 : p2;
}
#if RPL_DAG_MC == RPL_DAG_MC_NONE
static void
update_metric_container(rpl_instance_t *instance)
{
instance->mc.type = RPL_DAG_MC;
}
#else
static void
update_metric_container(rpl_instance_t *instance)
{
rpl_path_metric_t path_metric;
rpl_dag_t *dag;
#if RPL_DAG_MC == RPL_DAG_MC_ENERGY
uint8_t type;
#endif
instance->mc.type = RPL_DAG_MC;
instance->mc.flags = RPL_DAG_MC_FLAG_P;
instance->mc.aggr = RPL_DAG_MC_AGGR_ADDITIVE;
instance->mc.prec = 0;
dag = instance->current_dag;
if (!dag->joined) {
PRINTF("RPL: Cannot update the metric container when not joined\n");
return;
}
if(dag->rank == ROOT_RANK(instance)) {
path_metric = 0;
} else {
path_metric = calculate_path_metric(dag->preferred_parent);
}
#if RPL_DAG_MC == RPL_DAG_MC_ETX
instance->mc.length = sizeof(instance->mc.obj.etx);
instance->mc.obj.etx = path_metric;
PRINTF("RPL: My path ETX to the root is %u.%u\n",
instance->mc.obj.etx / RPL_DAG_MC_ETX_DIVISOR,
(instance->mc.obj.etx % RPL_DAG_MC_ETX_DIVISOR * 100) /
RPL_DAG_MC_ETX_DIVISOR);
#elif RPL_DAG_MC == RPL_DAG_MC_ENERGY
instance->mc.length = sizeof(instance->mc.obj.energy);
if(dag->rank == ROOT_RANK(instance)) {
type = RPL_DAG_MC_ENERGY_TYPE_MAINS;
} else {
type = RPL_DAG_MC_ENERGY_TYPE_BATTERY;
}
instance->mc.obj.energy.flags = type << RPL_DAG_MC_ENERGY_TYPE;
instance->mc.obj.energy.energy_est = path_metric;
#endif /* RPL_DAG_MC == RPL_DAG_MC_ETX */
}
#endif /* RPL_DAG_MC == RPL_DAG_MC_NONE */