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173 lines
5.0 KiB
C
173 lines
5.0 KiB
C
/**
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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 minrank-hysteresis objective function (OCP 1).
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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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*
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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/neighbor-info.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 parent_state_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_rank_t calculate_rank(rpl_parent_t *, rpl_rank_t);
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rpl_of_t rpl_of_etx = {
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reset,
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parent_state_callback,
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best_parent,
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calculate_rank,
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1
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};
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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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/* An initial guess of the link metric. */
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#define INITIAL_LINK_METRIC 3
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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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#define MAX_DIFFERENCE(dag) \
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((dag)->min_hoprankinc / PARENT_SWITCH_THRESHOLD_DIV)
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static rpl_rank_t min_path_cost = INFINITE_RANK;
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static void
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reset(rpl_dag_t *dag)
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{
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min_path_cost = INFINITE_RANK;
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}
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static void
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parent_state_callback(rpl_parent_t *parent, int known, int etx)
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{
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if(!known) {
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if(RPL_PARENT_COUNT(parent->dag) == 1) {
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/* Our last parent has disappeared, set the path ETX to INFINITE_RANK. */
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min_path_cost = INFINITE_RANK;
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}
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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 = INITIAL_LINK_METRIC * DEFAULT_MIN_HOPRANKINC;
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} else {
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if(p->etx == 0) {
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p->etx = INITIAL_LINK_METRIC * NEIGHBOR_INFO_ETX_DIVISOR;
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}
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rank_increase = (p->etx * p->dag->min_hoprankinc) / NEIGHBOR_INFO_ETX_DIVISOR;
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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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PRINTF("RPL: MRHOF calculate rank, base rank = %u, rank_increase = %u\n",
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(unsigned)base_rank, rank_increase);
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if(base_rank < min_path_cost) {
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min_path_cost = base_rank;
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PRINTF("RPL: min_path_cost updated to %u\n", min_path_cost);
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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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PRINTF("RPL: Path cost %u\n", (unsigned)new_rank);
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return new_rank;
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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_rank_t p1_rank;
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rpl_rank_t p2_rank;
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dag = (rpl_dag_t *)p1->dag; /* Both parents must be in the same DAG. */
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p1_rank = calculate_rank(p1, 0);
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p2_rank = calculate_rank(p2, 0);
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/* Maintain stability of the preferred parent in case of similar ranks. */
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if(p1_rank < p2_rank + MAX_DIFFERENCE(dag) &&
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p1_rank > p2_rank - MAX_DIFFERENCE(dag)) {
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PRINTF("RPL: MRHOF hysteresis: %u <= %u <= %u\n",
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p2_rank - MAX_DIFFERENCE(dag),
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p1_rank,
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p2_rank + MAX_DIFFERENCE(dag));
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return dag->preferred_parent;
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}
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if(p1_rank < p2_rank) {
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return p1;
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}
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return p2;
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}
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