/**
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* \addtogroup uip6
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* @{
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*/
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/*
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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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* \file
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* The Minimum Rank with Hysteresis Objective Function (MRHOF)
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*
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* This implementation uses the estimated number of
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* transmissions (ETX) as the additive routing metric,
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* and also provides stubs for the energy metric.
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*
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* \author Joakim Eriksson <joakime@sics.se>, Nicolas Tsiftes <nvt@sics.se>
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*/
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#include "net/rpl/rpl-private.h"
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#include "net/nbr-table.h"
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#define DEBUG DEBUG_NONE
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#include "net/uip-debug.h"
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static void reset(rpl_dag_t *);
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static void neighbor_link_callback(rpl_parent_t *, int, int);
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static rpl_parent_t *best_parent(rpl_parent_t *, rpl_parent_t *);
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static rpl_dag_t *best_dag(rpl_dag_t *, rpl_dag_t *);
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static rpl_rank_t calculate_rank(rpl_parent_t *, rpl_rank_t);
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static void update_metric_container(rpl_instance_t *);
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rpl_of_t rpl_mrhof = {
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reset,
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neighbor_link_callback,
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best_parent,
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best_dag,
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calculate_rank,
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update_metric_container,
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1
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};
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/* Constants for the ETX moving average */
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#define ETX_SCALE 100
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#define ETX_ALPHA 90
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/* Reject parents that have a higher link metric than the following. */
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#define MAX_LINK_METRIC 10
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/* Reject parents that have a higher path cost than the following. */
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#define MAX_PATH_COST 100
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/*
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* The rank must differ more than 1/PARENT_SWITCH_THRESHOLD_DIV in order
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* to switch preferred parent.
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*/
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#define PARENT_SWITCH_THRESHOLD_DIV 2
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typedef uint16_t rpl_path_metric_t;
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static rpl_path_metric_t
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calculate_path_metric(rpl_parent_t *p)
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{
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if(p == NULL) {
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return MAX_PATH_COST * RPL_DAG_MC_ETX_DIVISOR;
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}
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#if RPL_DAG_MC == RPL_DAG_MC_NONE
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return p->rank + (uint16_t)p->link_metric;
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#elif RPL_DAG_MC == RPL_DAG_MC_ETX
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return p->mc.obj.etx + (uint16_t)p->link_metric;
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#elif RPL_DAG_MC == RPL_DAG_MC_ENERGY
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return p->mc.obj.energy.energy_est + (uint16_t)p->link_metric;
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#else
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#error "Unsupported RPL_DAG_MC configured. See rpl.h."
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#endif /* RPL_DAG_MC */
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}
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static void
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reset(rpl_dag_t *sag)
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{
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PRINTF("RPL: Reset MRHOF\n");
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}
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static void
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neighbor_link_callback(rpl_parent_t *p, int status, int numtx)
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{
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uint16_t recorded_etx = p->link_metric;
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uint16_t packet_etx = numtx * RPL_DAG_MC_ETX_DIVISOR;
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uint16_t new_etx;
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/* Do not penalize the ETX when collisions or transmission errors occur. */
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if(status == MAC_TX_OK || status == MAC_TX_NOACK) {
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if(status == MAC_TX_NOACK) {
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packet_etx = MAX_LINK_METRIC * RPL_DAG_MC_ETX_DIVISOR;
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}
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new_etx = ((uint32_t)recorded_etx * ETX_ALPHA +
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(uint32_t)packet_etx * (ETX_SCALE - ETX_ALPHA)) / ETX_SCALE;
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PRINTF("RPL: ETX changed from %u to %u (packet ETX = %u)\n",
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(unsigned)(recorded_etx / RPL_DAG_MC_ETX_DIVISOR),
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(unsigned)(new_etx / RPL_DAG_MC_ETX_DIVISOR),
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(unsigned)(packet_etx / RPL_DAG_MC_ETX_DIVISOR));
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p->link_metric = new_etx;
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}
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}
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static rpl_rank_t
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calculate_rank(rpl_parent_t *p, rpl_rank_t base_rank)
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{
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rpl_rank_t new_rank;
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rpl_rank_t rank_increase;
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if(p == NULL) {
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if(base_rank == 0) {
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return INFINITE_RANK;
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}
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rank_increase = RPL_INIT_LINK_METRIC * RPL_DAG_MC_ETX_DIVISOR;
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} else {
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rank_increase = p->link_metric;
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if(base_rank == 0) {
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base_rank = p->rank;
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}
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}
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if(INFINITE_RANK - base_rank < rank_increase) {
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/* Reached the maximum rank. */
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new_rank = INFINITE_RANK;
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} else {
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/* Calculate the rank based on the new rank information from DIO or
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stored otherwise. */
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new_rank = base_rank + rank_increase;
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}
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return new_rank;
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}
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static rpl_dag_t *
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best_dag(rpl_dag_t *d1, rpl_dag_t *d2)
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{
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if(d1->grounded != d2->grounded) {
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return d1->grounded ? d1 : d2;
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}
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if(d1->preference != d2->preference) {
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return d1->preference > d2->preference ? d1 : d2;
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}
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return d1->rank < d2->rank ? d1 : d2;
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}
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static rpl_parent_t *
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best_parent(rpl_parent_t *p1, rpl_parent_t *p2)
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{
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rpl_dag_t *dag;
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rpl_path_metric_t min_diff;
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rpl_path_metric_t p1_metric;
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rpl_path_metric_t p2_metric;
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dag = p1->dag; /* Both parents are in the same DAG. */
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min_diff = RPL_DAG_MC_ETX_DIVISOR /
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PARENT_SWITCH_THRESHOLD_DIV;
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p1_metric = calculate_path_metric(p1);
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p2_metric = calculate_path_metric(p2);
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/* Maintain stability of the preferred parent in case of similar ranks. */
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if(p1 == dag->preferred_parent || p2 == dag->preferred_parent) {
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if(p1_metric < p2_metric + min_diff &&
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p1_metric > p2_metric - min_diff) {
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PRINTF("RPL: MRHOF hysteresis: %u <= %u <= %u\n",
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p2_metric - min_diff,
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p1_metric,
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p2_metric + min_diff);
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return dag->preferred_parent;
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}
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}
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return p1_metric < p2_metric ? p1 : p2;
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}
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#if RPL_DAG_MC == RPL_DAG_MC_NONE
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static void
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update_metric_container(rpl_instance_t *instance)
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{
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instance->mc.type = RPL_DAG_MC;
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}
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#else
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static void
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update_metric_container(rpl_instance_t *instance)
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{
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rpl_path_metric_t path_metric;
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rpl_dag_t *dag;
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#if RPL_DAG_MC == RPL_DAG_MC_ENERGY
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uint8_t type;
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#endif
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instance->mc.type = RPL_DAG_MC;
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instance->mc.flags = RPL_DAG_MC_FLAG_P;
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instance->mc.aggr = RPL_DAG_MC_AGGR_ADDITIVE;
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instance->mc.prec = 0;
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dag = instance->current_dag;
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if (!dag->joined) {
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PRINTF("RPL: Cannot update the metric container when not joined\n");
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return;
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}
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if(dag->rank == ROOT_RANK(instance)) {
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path_metric = 0;
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} else {
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path_metric = calculate_path_metric(dag->preferred_parent);
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}
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#if RPL_DAG_MC == RPL_DAG_MC_ETX
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instance->mc.length = sizeof(instance->mc.obj.etx);
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instance->mc.obj.etx = path_metric;
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PRINTF("RPL: My path ETX to the root is %u.%u\n",
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instance->mc.obj.etx / RPL_DAG_MC_ETX_DIVISOR,
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(instance->mc.obj.etx % RPL_DAG_MC_ETX_DIVISOR * 100) /
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RPL_DAG_MC_ETX_DIVISOR);
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#elif RPL_DAG_MC == RPL_DAG_MC_ENERGY
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instance->mc.length = sizeof(instance->mc.obj.energy);
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if(dag->rank == ROOT_RANK(instance)) {
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type = RPL_DAG_MC_ENERGY_TYPE_MAINS;
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} else {
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type = RPL_DAG_MC_ENERGY_TYPE_BATTERY;
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}
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instance->mc.obj.energy.flags = type << RPL_DAG_MC_ENERGY_TYPE;
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instance->mc.obj.energy.energy_est = path_metric;
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#endif /* RPL_DAG_MC == RPL_DAG_MC_ETX */
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}
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#endif /* RPL_DAG_MC == RPL_DAG_MC_NONE */
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