osd-contiki/core/net/rpl/rpl-of-etx.c
2011-02-13 14:14:49 +01:00

173 lines
5 KiB
C

/**
* \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 minrank-hysteresis objective function (OCP 1).
*
* This implementation uses the estimated number of
* transmissions (ETX) as the additive routing metric.
*
* \author Joakim Eriksson <joakime@sics.se>, Nicolas Tsiftes <nvt@sics.se>
*/
#include "net/rpl/rpl-private.h"
#include "net/neighbor-info.h"
#define DEBUG DEBUG_NONE
#include "net/uip-debug.h"
static void reset(rpl_dag_t *);
static void parent_state_callback(rpl_parent_t *, int, int);
static rpl_parent_t *best_parent(rpl_parent_t *, rpl_parent_t *);
static rpl_rank_t calculate_rank(rpl_parent_t *, rpl_rank_t);
rpl_of_t rpl_of_etx = {
reset,
parent_state_callback,
best_parent,
calculate_rank,
1
};
/* 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
/* An initial guess of the link metric. */
#define INITIAL_LINK_METRIC 3
/*
* The rank must differ more than 1/PARENT_SWITCH_THRESHOLD_DIV in order
* to switch preferred parent.
*/
#define PARENT_SWITCH_THRESHOLD_DIV 2
#define MAX_DIFFERENCE(dag) \
((dag)->min_hoprankinc / PARENT_SWITCH_THRESHOLD_DIV)
static rpl_rank_t min_path_cost = INFINITE_RANK;
static void
reset(rpl_dag_t *dag)
{
min_path_cost = INFINITE_RANK;
}
static void
parent_state_callback(rpl_parent_t *parent, int known, int etx)
{
if(!known) {
if(RPL_PARENT_COUNT(parent->dag) == 1) {
/* Our last parent has disappeared, set the path ETX to INFINITE_RANK. */
min_path_cost = INFINITE_RANK;
}
}
}
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 = INITIAL_LINK_METRIC * DEFAULT_MIN_HOPRANKINC;
} else {
if(p->etx == 0) {
p->etx = INITIAL_LINK_METRIC * ETX_DIVISOR;
}
rank_increase = (p->etx * p->dag->min_hoprankinc) / ETX_DIVISOR;
if(base_rank == 0) {
base_rank = p->rank;
}
}
PRINTF("RPL: MRHOF calculate rank, base rank = %u, rank_increase = %u\n",
(unsigned)base_rank, rank_increase);
if(base_rank < min_path_cost) {
min_path_cost = base_rank;
PRINTF("RPL: min_path_cost updated to %u\n", min_path_cost);
}
if(INFINITE_RANK - base_rank < rank_increase) {
/* 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;
}
PRINTF("RPL: Path cost %u\n", (unsigned)new_rank);
return new_rank;
}
static rpl_parent_t *
best_parent(rpl_parent_t *p1, rpl_parent_t *p2)
{
rpl_dag_t *dag;
rpl_rank_t p1_rank;
rpl_rank_t p2_rank;
dag = (rpl_dag_t *)p1->dag; /* Both parents must be in the same DAG. */
p1_rank = calculate_rank(p1, 0);
p2_rank = calculate_rank(p2, 0);
/* Maintain stability of the preferred parent in case of similar ranks. */
if(p1_rank < p2_rank + MAX_DIFFERENCE(dag) &&
p1_rank > p2_rank - MAX_DIFFERENCE(dag)) {
PRINTF("RPL: MRHOF hysteresis: %u <= %u <= %u\n",
p2_rank - MAX_DIFFERENCE(dag),
p1_rank,
p2_rank + MAX_DIFFERENCE(dag));
return dag->preferred_parent;
}
if(p1_rank < p2_rank) {
return p1;
}
return p2;
}