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

306 lines
10 KiB
C

/*
* 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), RFC6719
*
* 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>
*/
/**
* \addtogroup uip6
* @{
*/
#include "net/rpl/rpl.h"
#include "net/rpl/rpl-private.h"
#include "net/nbr-table.h"
#include "net/link-stats.h"
#define DEBUG DEBUG_NONE
#include "net/ip/uip-debug.h"
/* RFC6551 and RFC6719 do not mandate the use of a specific formula to
* compute the ETX value. This MRHOF implementation relies on the value
* computed by the link-stats module. It has an optional feature,
* RPL_MRHOF_CONF_SQUARED_ETX, that consists in squaring this value.
* This basically penalizes bad links while preserving the semantics of ETX
* (1 = perfect link, more = worse link). As a result, MRHOF will favor
* good links over short paths. Recommended when reliability is a priority.
* Without this feature, a hop with 50% PRR (ETX=2) is equivalent to two
* perfect hops with 100% PRR (ETX=1+1=2). With this feature, the former
* path obtains ETX=2*2=4 and the former ETX=1*1+1*1=2. */
#ifdef RPL_MRHOF_CONF_SQUARED_ETX
#define RPL_MRHOF_SQUARED_ETX RPL_MRHOF_CONF_SQUARED_ETX
#else /* RPL_MRHOF_CONF_SQUARED_ETX */
#define RPL_MRHOF_SQUARED_ETX 0
#endif /* RPL_MRHOF_CONF_SQUARED_ETX */
/* Configuration parameters of RFC6719. Reject parents that have a higher
* link metric than the following. We use the default values from the RFC. */
#define MAX_LINK_METRIC 512 /* Eq ETX of 4 */
/* Reject parents that have a higher path cost than the following. */
#define MAX_PATH_COST 32768 /* Eq path ETX of 256 */
/* Hysteresis of MRHOF: the rank must differ more than PARENT_SWITCH_THRESHOLD_DIV
* in order to switch preferred parent. Default in RFC6719: 192, eq ETX of 1.5.
* We use a more aggressive setting: 96, eq ETX of 0.75.
*/
#define PARENT_SWITCH_THRESHOLD 96
/*---------------------------------------------------------------------------*/
static void
reset(rpl_dag_t *dag)
{
PRINTF("RPL: Reset MRHOF\n");
}
/*---------------------------------------------------------------------------*/
#if RPL_WITH_DAO_ACK
static void
dao_ack_callback(rpl_parent_t *p, int status)
{
if(status == RPL_DAO_ACK_UNABLE_TO_ADD_ROUTE_AT_ROOT) {
return;
}
/* here we need to handle failed DAO's and other stuff */
PRINTF("RPL: MRHOF - DAO ACK received with status: %d\n", status);
if(status >= RPL_DAO_ACK_UNABLE_TO_ACCEPT) {
/* punish the ETX as if this was 10 packets lost */
neighbor_link_callback(p, MAC_TX_OK, 10);
} else if(status == RPL_DAO_ACK_TIMEOUT) { /* timeout = no ack */
/* punish the total lack of ACK with a similar punishment */
neighbor_link_callback(p, MAC_TX_OK, 10);
}
}
#endif /* RPL_WITH_DAO_ACK */
/*---------------------------------------------------------------------------*/
static uint16_t
parent_link_metric(rpl_parent_t *p)
{
const struct link_stats *stats = rpl_get_parent_link_stats(p);
if(stats != NULL) {
#if RPL_MRHOF_SQUARED_ETX
uint32_t squared_etx = ((uint32_t)stats->etx * stats->etx) / LINK_STATS_ETX_DIVISOR;
return (uint16_t)MIN(squared_etx, 0xffff);
#else /* RPL_MRHOF_SQUARED_ETX */
return stats->etx;
#endif /* RPL_MRHOF_SQUARED_ETX */
}
return 0xffff;
}
/*---------------------------------------------------------------------------*/
static uint16_t
parent_path_cost(rpl_parent_t *p)
{
uint16_t base;
if(p == NULL || p->dag == NULL || p->dag->instance == NULL) {
return 0xffff;
}
#if RPL_WITH_MC
/* Handle the different MC types */
switch(p->dag->instance->mc.type) {
case RPL_DAG_MC_ETX:
base = p->mc.obj.etx;
break;
case RPL_DAG_MC_ENERGY:
base = p->mc.obj.energy.energy_est << 8;
break;
default:
base = p->rank;
break;
}
#else /* RPL_WITH_MC */
base = p->rank;
#endif /* RPL_WITH_MC */
/* path cost upper bound: 0xffff */
return MIN((uint32_t)base + parent_link_metric(p), 0xffff);
}
/*---------------------------------------------------------------------------*/
static rpl_rank_t
rank_via_parent(rpl_parent_t *p)
{
uint16_t min_hoprankinc;
uint16_t path_cost;
if(p == NULL || p->dag == NULL || p->dag->instance == NULL) {
return INFINITE_RANK;
}
min_hoprankinc = p->dag->instance->min_hoprankinc;
path_cost = parent_path_cost(p);
/* Rank lower-bound: parent rank + min_hoprankinc */
return MAX(MIN((uint32_t)p->rank + min_hoprankinc, 0xffff), path_cost);
}
/*---------------------------------------------------------------------------*/
static int
parent_is_acceptable(rpl_parent_t *p)
{
uint16_t link_metric = parent_link_metric(p);
uint16_t path_cost = parent_path_cost(p);
/* Exclude links with too high link metrics or path cost (RFC6719, 3.2.2) */
return link_metric <= MAX_LINK_METRIC && path_cost <= MAX_PATH_COST;
}
/*---------------------------------------------------------------------------*/
static rpl_parent_t *
best_parent(rpl_parent_t *p1, rpl_parent_t *p2)
{
rpl_dag_t *dag;
uint16_t p1_cost;
uint16_t p2_cost;
int p1_is_acceptable;
int p2_is_acceptable;
if(p1 == NULL || p2 == NULL) {
/* Return non-null parent if any */
return p1 == NULL ? p2 : p1;
}
p1_is_acceptable = parent_is_acceptable(p1);
p2_is_acceptable = parent_is_acceptable(p2);
/* Is only one parent is acceptable, select it. If both are acceptable, or
* both non-acceptable, proceed to traditional parent comparison. This is a
* slight departure from the standard but allows to keep connectivity even
* all neighbors appear to have a bad link. */
if(p1_is_acceptable != p2_is_acceptable) {
return p1_is_acceptable ? p1 : p2;
}
dag = p1->dag; /* Both parents are in the same DAG. */
p1_cost = parent_path_cost(p1);
p2_cost = parent_path_cost(p2);
/* Maintain stability of the preferred parent in case of similar ranks. */
if(p1 == dag->preferred_parent || p2 == dag->preferred_parent) {
if(p1_cost < p2_cost + PARENT_SWITCH_THRESHOLD &&
p1_cost > p2_cost - PARENT_SWITCH_THRESHOLD) {
return dag->preferred_parent;
}
}
return p1_cost < p2_cost ? p1 : p2;
}
/*---------------------------------------------------------------------------*/
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;
}
/*---------------------------------------------------------------------------*/
#if !RPL_WITH_MC
static void
update_metric_container(rpl_instance_t *instance)
{
instance->mc.type = RPL_DAG_MC_NONE;
}
#else /* RPL_WITH_MC */
static void
update_metric_container(rpl_instance_t *instance)
{
rpl_dag_t *dag;
uint16_t path_cost;
uint8_t type;
dag = instance->current_dag;
if(dag == NULL || !dag->joined) {
PRINTF("RPL: Cannot update the metric container when not joined\n");
return;
}
if(dag->rank == ROOT_RANK(instance)) {
/* Configure MC at root only, other nodes are auto-configured when joining */
instance->mc.type = RPL_DAG_MC;
instance->mc.flags = 0;
instance->mc.aggr = RPL_DAG_MC_AGGR_ADDITIVE;
instance->mc.prec = 0;
path_cost = dag->rank;
} else {
path_cost = parent_path_cost(dag->preferred_parent);
}
/* Handle the different MC types */
switch(instance->mc.type) {
case RPL_DAG_MC_NONE:
break;
case RPL_DAG_MC_ETX:
instance->mc.length = sizeof(instance->mc.obj.etx);
instance->mc.obj.etx = path_cost;
break;
case 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;
/* Energy_est is only one byte, use the least significant byte of the path metric. */
instance->mc.obj.energy.energy_est = path_cost >> 8;
break;
default:
PRINTF("RPL: MRHOF, non-supported MC %u\n", instance->mc.type);
break;
}
}
#endif /* RPL_WITH_MC */
/*---------------------------------------------------------------------------*/
rpl_of_t rpl_mrhof = {
reset,
#if RPL_WITH_DAO_ACK
dao_ack_callback,
#endif
parent_link_metric,
parent_path_cost,
rank_via_parent,
best_parent,
best_dag,
update_metric_container,
RPL_OCP_MRHOF
};
/** @}*/