317 lines
10 KiB
C
317 lines
10 KiB
C
/*
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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), RFC6719
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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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/**
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* \addtogroup uip6
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* @{
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*/
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#include "net/rpl-classic/rpl.h"
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#include "net/rpl-classic/rpl-private.h"
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#include "net/nbr-table.h"
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#include "net/link-stats.h"
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#define DEBUG DEBUG_NONE
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#include "net/ip/uip-debug.h"
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/* RFC6551 and RFC6719 do not mandate the use of a specific formula to
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* compute the ETX value. This MRHOF implementation relies on the value
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* computed by the link-stats module. It has an optional feature,
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* RPL_MRHOF_CONF_SQUARED_ETX, that consists in squaring this value.
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* This basically penalizes bad links while preserving the semantics of ETX
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* (1 = perfect link, more = worse link). As a result, MRHOF will favor
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* good links over short paths. Recommended when reliability is a priority.
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* Without this feature, a hop with 50% PRR (ETX=2) is equivalent to two
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* perfect hops with 100% PRR (ETX=1+1=2). With this feature, the former
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* path obtains ETX=2*2=4 and the former ETX=1*1+1*1=2. */
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#ifdef RPL_MRHOF_CONF_SQUARED_ETX
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#define RPL_MRHOF_SQUARED_ETX RPL_MRHOF_CONF_SQUARED_ETX
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#else /* RPL_MRHOF_CONF_SQUARED_ETX */
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#define RPL_MRHOF_SQUARED_ETX 0
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#endif /* RPL_MRHOF_CONF_SQUARED_ETX */
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#if !RPL_MRHOF_SQUARED_ETX
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/* Configuration parameters of RFC6719. Reject parents that have a higher
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* link metric than the following. The default value is 512 but we use 1024. */
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#define MAX_LINK_METRIC 1024 /* Eq ETX of 8 */
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/* Hysteresis of MRHOF: the rank must differ more than PARENT_SWITCH_THRESHOLD_DIV
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* in order to switch preferred parent. Default in RFC6719: 192, eq ETX of 1.5.
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* We use a more aggressive setting: 96, eq ETX of 0.75.
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*/
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#define PARENT_SWITCH_THRESHOLD 96 /* Eq ETX of 0.75 */
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#else /* !RPL_MRHOF_SQUARED_ETX */
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#define MAX_LINK_METRIC 2048 /* Eq ETX of 4 */
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#define PARENT_SWITCH_THRESHOLD 160 /* Eq ETX of 1.25 (results in a churn comparable
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to the threshold of 96 in the non-squared case) */
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#endif /* !RPL_MRHOF_SQUARED_ETX */
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/* Reject parents that have a higher path cost than the following. */
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#define MAX_PATH_COST 32768 /* Eq path ETX of 256 */
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/*---------------------------------------------------------------------------*/
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static void
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reset(rpl_dag_t *dag)
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{
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PRINTF("RPL: Reset MRHOF\n");
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}
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/*---------------------------------------------------------------------------*/
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#if RPL_WITH_DAO_ACK
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static void
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dao_ack_callback(rpl_parent_t *p, int status)
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{
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if(status == RPL_DAO_ACK_UNABLE_TO_ADD_ROUTE_AT_ROOT) {
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return;
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}
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/* here we need to handle failed DAO's and other stuff */
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PRINTF("RPL: MRHOF - DAO ACK received with status: %d\n", status);
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if(status >= RPL_DAO_ACK_UNABLE_TO_ACCEPT) {
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/* punish the ETX as if this was 10 packets lost */
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link_stats_packet_sent(rpl_get_parent_lladdr(p), MAC_TX_OK, 10);
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} else if(status == RPL_DAO_ACK_TIMEOUT) { /* timeout = no ack */
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/* punish the total lack of ACK with a similar punishment */
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link_stats_packet_sent(rpl_get_parent_lladdr(p), MAC_TX_OK, 10);
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}
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}
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#endif /* RPL_WITH_DAO_ACK */
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/*---------------------------------------------------------------------------*/
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static uint16_t
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parent_link_metric(rpl_parent_t *p)
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{
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const struct link_stats *stats = rpl_get_parent_link_stats(p);
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if(stats != NULL) {
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#if RPL_MRHOF_SQUARED_ETX
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uint32_t squared_etx = ((uint32_t)stats->etx * stats->etx) / LINK_STATS_ETX_DIVISOR;
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return (uint16_t)MIN(squared_etx, 0xffff);
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#else /* RPL_MRHOF_SQUARED_ETX */
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return stats->etx;
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#endif /* RPL_MRHOF_SQUARED_ETX */
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}
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return 0xffff;
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}
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/*---------------------------------------------------------------------------*/
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static uint16_t
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parent_path_cost(rpl_parent_t *p)
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{
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uint16_t base;
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if(p == NULL || p->dag == NULL || p->dag->instance == NULL) {
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return 0xffff;
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}
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#if RPL_WITH_MC
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/* Handle the different MC types */
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switch(p->dag->instance->mc.type) {
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case RPL_DAG_MC_ETX:
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base = p->mc.obj.etx;
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break;
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case RPL_DAG_MC_ENERGY:
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base = p->mc.obj.energy.energy_est << 8;
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break;
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default:
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base = p->rank;
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break;
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}
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#else /* RPL_WITH_MC */
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base = p->rank;
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#endif /* RPL_WITH_MC */
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/* path cost upper bound: 0xffff */
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return MIN((uint32_t)base + parent_link_metric(p), 0xffff);
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}
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/*---------------------------------------------------------------------------*/
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static rpl_rank_t
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rank_via_parent(rpl_parent_t *p)
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{
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uint16_t min_hoprankinc;
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uint16_t path_cost;
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if(p == NULL || p->dag == NULL || p->dag->instance == NULL) {
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return RPL_INFINITE_RANK;
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}
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min_hoprankinc = p->dag->instance->min_hoprankinc;
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path_cost = parent_path_cost(p);
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/* Rank lower-bound: parent rank + min_hoprankinc */
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return MAX(MIN((uint32_t)p->rank + min_hoprankinc, 0xffff), path_cost);
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}
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/*---------------------------------------------------------------------------*/
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static int
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parent_is_acceptable(rpl_parent_t *p)
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{
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uint16_t link_metric = parent_link_metric(p);
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uint16_t path_cost = parent_path_cost(p);
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/* Exclude links with too high link metrics or path cost (RFC6719, 3.2.2) */
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return link_metric <= MAX_LINK_METRIC && path_cost <= MAX_PATH_COST;
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}
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/*---------------------------------------------------------------------------*/
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static int
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parent_has_usable_link(rpl_parent_t *p)
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{
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uint16_t link_metric = parent_link_metric(p);
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/* Exclude links with too high link metrics */
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return link_metric <= MAX_LINK_METRIC;
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}
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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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uint16_t p1_cost;
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uint16_t p2_cost;
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int p1_is_acceptable;
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int p2_is_acceptable;
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p1_is_acceptable = p1 != NULL && parent_is_acceptable(p1);
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p2_is_acceptable = p2 != NULL && parent_is_acceptable(p2);
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if(!p1_is_acceptable) {
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return p2_is_acceptable ? p2 : NULL;
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}
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if(!p2_is_acceptable) {
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return p1_is_acceptable ? p1 : NULL;
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}
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dag = p1->dag; /* Both parents are in the same DAG. */
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p1_cost = parent_path_cost(p1);
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p2_cost = parent_path_cost(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_cost < p2_cost + PARENT_SWITCH_THRESHOLD &&
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p1_cost > p2_cost - PARENT_SWITCH_THRESHOLD) {
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return dag->preferred_parent;
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}
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}
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return p1_cost < p2_cost ? p1 : p2;
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}
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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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/*---------------------------------------------------------------------------*/
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#if !RPL_WITH_MC
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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_NONE;
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}
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#else /* RPL_WITH_MC */
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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_dag_t *dag;
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uint16_t path_cost;
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uint8_t type;
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dag = instance->current_dag;
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if(dag == NULL || !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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/* Configure MC at root only, other nodes are auto-configured when joining */
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instance->mc.type = RPL_DAG_MC;
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instance->mc.flags = 0;
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instance->mc.aggr = RPL_DAG_MC_AGGR_ADDITIVE;
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instance->mc.prec = 0;
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path_cost = dag->rank;
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} else {
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path_cost = parent_path_cost(dag->preferred_parent);
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}
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/* Handle the different MC types */
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switch(instance->mc.type) {
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case RPL_DAG_MC_NONE:
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break;
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case 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_cost;
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break;
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case 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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/* Energy_est is only one byte, use the least significant byte of the path metric. */
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instance->mc.obj.energy.energy_est = path_cost >> 8;
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break;
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default:
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PRINTF("RPL: MRHOF, non-supported MC %u\n", instance->mc.type);
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break;
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}
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}
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#endif /* RPL_WITH_MC */
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/*---------------------------------------------------------------------------*/
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rpl_of_t rpl_mrhof = {
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reset,
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#if RPL_WITH_DAO_ACK
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dao_ack_callback,
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#endif
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parent_link_metric,
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parent_has_usable_link,
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parent_path_cost,
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rank_via_parent,
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best_parent,
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best_dag,
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update_metric_container,
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RPL_OCP_MRHOF
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};
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/** @}*/
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