Added robustness on DAO-ACK handling

inform routing core if DAO ACK is missing that will result in changing
of immediate route to secondary.

Added limit of DAO retries before the RPL neighbour information is reset

Author: Mika Tervonen

source/6LoWPAN/ws/ws_bootstrap.c

@@ -2055,6 +2055,8 @@ static void ws_bootstrap_rpl_activate(protocol_interface_info_entry_t *cur)
     // If i am router I Do this
     rpl_control_force_leaf(protocol_6lowpan_rpl_domain, leaf);
     rpl_control_request_parent_link_confirmation(true);
+    rpl_control_set_dao_retry_count(WS_MAX_DAO_RETRIES);
+    rpl_control_set_initial_dao_ack_wait(WS_MAX_DAO_INITIAL_TIMEOUT);
 
     cur->ws_info->rpl_state = 0xff; // Set invalid state and learn from event
 }

source/6LoWPAN/ws/ws_config.h

@@ -133,4 +133,11 @@ extern uint8_t DEVICE_MIN_SENS;
 #define FRAME_COUNTER_INCREMENT          1000 // How much frame counter is incremented on start up
 #define FRAME_COUNTER_STORE_THRESHOLD    800  // How much frame counter must increment before it is stored
 
+
+/*
+ *  RPL Configuration parameters
+ */
+#define WS_MAX_DAO_RETRIES 3 // With 40s, 80s, 160s, 320s, 640s
+#define WS_MAX_DAO_INITIAL_TIMEOUT 400 // With 40s initial value exponentially increasing
+
 #endif /* WS_CONFIG_H_ */

source/RPL/rpl_control.c

@@ -176,6 +176,16 @@ void rpl_control_request_parent_link_confirmation(bool requested)
     rpl_policy_set_parent_confirmation_request(requested);
 }
 
+void rpl_control_set_dao_retry_count(uint8_t count)
+{
+    rpl_policy_set_dao_retry_count(count);
+}
+
+void rpl_control_set_initial_dao_ack_wait(uint16_t timeout_in_ms)
+{
+    rpl_policy_set_initial_dao_ack_wait(timeout_in_ms);
+}
+
 /* Send address registration to either specified address, or to non-registered address */
 void rpl_control_register_address(protocol_interface_info_entry_t *interface, const uint8_t addr[16])
 {

source/RPL/rpl_control.h

@@ -156,6 +156,8 @@ uint16_t rpl_control_parent_candidate_list_size(struct protocol_interface_info_e
 void rpl_control_neighbor_delete(struct protocol_interface_info_entry *interface, const uint8_t ll_addr[16]);
 /* Parent link confirmation API extension */
 void rpl_control_request_parent_link_confirmation(bool requested);
+void rpl_control_set_dao_retry_count(uint8_t count);
+void rpl_control_set_initial_dao_ack_wait(uint16_t timeout_in_ms);
 void rpl_control_register_address(struct protocol_interface_info_entry *interface, const uint8_t addr[16]);
 void rpl_control_address_register_done(struct protocol_interface_info_entry *interface, const uint8_t ll_addr[16], uint8_t status);
 

source/RPL/rpl_downward.c

@@ -712,6 +712,21 @@ void rpl_instance_send_dao_update(rpl_instance_t *instance)
         return;
     }
 
+    if (rpl_policy_dao_retry_count() > 0 && instance->dao_attempt >= rpl_policy_dao_retry_count()) {
+        // Check if recovery logic is started
+        // after half the retries are done we remove the primary parent
+        tr_info("DAO remove primary parent");
+        rpl_neighbour_t *neighbour = ns_list_get_first(&instance->candidate_neighbours);
+        if (neighbour) {
+            rpl_delete_neighbour(instance, neighbour);
+        }
+        // Set parameters to restart
+        instance->dao_in_transit = false;
+        instance->dao_attempt = 0;
+        instance->dao_retry_timer = 0;
+        instance->delay_dao_timer = 0;
+        return;
+    }
 
     /* Which parent this DAO will be for if storing */
     rpl_neighbour_t *parent = NULL;
@@ -847,6 +862,15 @@ void rpl_instance_send_dao_update(rpl_instance_t *instance)
         cur = NULL;
     }
 
+    if (instance->dao_attempt > 0) {
+        // Start informing problem in routing. This will cause us to select secondary routes when sending the DAO
+        tr_info("DAO reachability problem");
+        protocol_interface_info_entry_t *interface = protocol_stack_interface_info_get_by_rpl_domain(instance->domain, -1);
+        if (interface) {
+            ipv6_neighbour_reachability_problem(dst, interface->id);
+        }
+    }
+
     bool need_ack = rpl_control_transmit_dao(instance->domain, cur, instance, instance->id, instance->dao_sequence, dodag->id, opts, ptr - opts, dst);
     ns_dyn_mem_free(opts);
 

source/RPL/rpl_policy.c

@@ -35,6 +35,8 @@
 #define TRACE_GROUP "RPLy"
 
 static bool rpl_policy_parent_confirmation_req = false;
+static int8_t rpl_policy_dao_retry_count_conf = 0;
+static int16_t rpl_policy_dao_initial_timeout_conf = 20; // Default is 2 seconds 100ms ticks
 
 /* TODO - application API to control when to join new instances / DODAGs
  *
@@ -105,6 +107,11 @@ bool rpl_policy_request_dao_acks(const rpl_domain_t *domain, uint8_t mop)
     return true;
 }
 
+void rpl_policy_set_initial_dao_ack_wait(uint16_t timeout_in_ms)
+{
+    rpl_policy_dao_initial_timeout_conf = timeout_in_ms;
+}
+
 uint16_t rpl_policy_initial_dao_ack_wait(const rpl_domain_t *domain, uint8_t mop)
 {
     (void)mop;
@@ -120,7 +127,18 @@ uint16_t rpl_policy_initial_dao_ack_wait(const rpl_domain_t *domain, uint8_t mop
         }
     }
 
-    return 20; /* *100ms ticks = 2s */
+    return rpl_policy_dao_initial_timeout_conf;
+}
+
+
+void rpl_policy_set_dao_retry_count(uint8_t count)
+{
+    rpl_policy_dao_retry_count_conf = count;
+}
+
+int8_t rpl_policy_dao_retry_count()
+{
+    return rpl_policy_dao_retry_count_conf;
 }
 
 /* Given the next-hop address from a source routing header, which interface,

source/RPL/rpl_policy.h

@@ -27,6 +27,11 @@ bool rpl_policy_join_config(rpl_domain_t *domain, const rpl_dodag_conf_t *conf,
 
 bool rpl_policy_request_dao_acks(const rpl_domain_t *domain, uint8_t mop);
 uint16_t rpl_policy_initial_dao_ack_wait(const rpl_domain_t *domain, uint8_t mop);
+void rpl_policy_set_initial_dao_ack_wait(uint16_t timeout_in_ms);
+
+void rpl_policy_set_dao_retry_count(uint8_t count);
+int8_t rpl_policy_dao_retry_count();
+
 int8_t rpl_policy_srh_next_hop_interface(rpl_domain_t *domain, int8_t if_id, const uint8_t *next_hop);
 uint16_t rpl_policy_modify_downward_cost_to_root_neighbour(rpl_domain_t *domain, int8_t if_id, const uint8_t *next_hop, uint16_t cost);
 

test/nanostack/unittest/stub/rpl_control_stub.c

@@ -243,3 +243,13 @@ void rpl_control_request_parent_link_confirmation(bool requested)
 {
 
 }
+
+void rpl_control_set_dao_retry_count(uint8_t count)
+{
+
+}
+
+void rpl_control_set_initial_dao_ack_wait(uint16_t timeout_in_ms)
+{
+
+}

test/nanostack/unittest/stub/rpl_policy_stub.c

@@ -54,6 +54,9 @@ bool rpl_policy_request_dao_acks(const rpl_domain_t *domain, uint8_t mop)
 {
     return false;
 }
+void rpl_policy_set_initial_dao_ack_wait(uint16_t timeout_in_ms)
+{
+}
 
 uint16_t rpl_policy_initial_dao_ack_wait(const rpl_domain_t *domain, uint8_t mop)
 {
@@ -174,5 +177,14 @@ void rpl_policy_set_parent_confirmation_request(bool confirmation_requested)
 {
 
 }
+void rpl_policy_set_dao_retry_count(uint8_t count)
+{
+
+}
+
+int8_t rpl_policy_dao_retry_count()
+{
+    return 0;
+}
 
 #endif /* HAVE_RPL */