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Handle case when old rnti gets removed during RRC reestablishment

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This is achieved via:
- keep restarting the inactivity timer whenever a ReestablishmentRequest is received
- in case the RRC ReestablishmentComplete is very late and the old rnti was removed anyway,
  abort RRC reestablishment procedure and release new rnti
master
Francisco 4 years ago committed by Francisco Paisana
parent b2825d1280
commit 46cfdaf9e5
2 changed files with 88 additions and 73 deletions
Show Stats Download Patch File Download Diff File

8
srsenb/hdr/stack/rrc/rrc_ue.h
Unescape Escape View File

@ -157,12 +157,12 @@ public:
bool is_csfb = false;
private:
srsran::timer_handler::unique_timer activity_timer; // for basic DL/UL activity timeout
srsran::unique_timer activity_timer; // for basic DL/UL activity timeout
/// Radio link failure handling uses distinct timers for PHY (DL and UL) and RLC signaled RLF
srsran::timer_handler::unique_timer phy_dl_rlf_timer; // can be stopped through recovered DL activity
srsran::timer_handler::unique_timer phy_ul_rlf_timer; // can be stopped through recovered UL activity
srsran::timer_handler::unique_timer rlc_rlf_timer; // can only be stoped through UE reestablishment
srsran::unique_timer phy_dl_rlf_timer; // can be stopped through recovered DL activity
srsran::unique_timer phy_ul_rlf_timer; // can be stopped through recovered UL activity
srsran::unique_timer rlc_rlf_timer; // can only be stoped through UE reestablishment
/// cached ASN1 fields for RRC config update checking, and ease of context transfer during HO
ue_var_cfg_t current_ue_cfg;

83
srsenb/src/stack/rrc/rrc_ue.cc
Unescape Escape View File

@ -522,9 +522,6 @@ void rrc::ue::handle_rrc_con_reest_req(rrc_conn_reest_request_s* msg)
const rrc_conn_reest_request_r8_ies_s& req_r8 = msg->crit_exts.rrc_conn_reest_request_r8();
uint16_t old_rnti = req_r8.ue_id.c_rnti.to_number();
srsran::console(
"User 0x%x requesting RRC Reestablishment as 0x%x. Cause: %s\n", rnti, old_rnti, req_r8.reest_cause.to_string());
if (not parent->s1ap->is_mme_connected()) {
parent->logger.error("MME isn't connected. Sending Connection Reject");
send_connection_reest_rej(procedure_result_code::error_mme_not_connected);
@ -536,31 +533,50 @@ void rrc::ue::handle_rrc_con_reest_req(rrc_conn_reest_request_s* msg)
msg->crit_exts.rrc_conn_reest_request_r8().ue_id.pci,
(uint32_t)msg->crit_exts.rrc_conn_reest_request_r8().ue_id.short_mac_i.to_number(),
msg->crit_exts.rrc_conn_reest_request_r8().reest_cause.to_string());
if (is_idle()) {
if (not is_idle()) {
// The created RNTI has to receive ReestablishmentRequest as first message
parent->logger.error("Received ReestablishmentRequest from an rnti=0x%x not in IDLE", rnti);
send_connection_reest_rej(procedure_result_code::error_unknown_rnti);
srsran::console("ERROR: User 0x%x requesting Reestablishment is not in RRC_IDLE\n", rnti);
return;
}
uint16_t old_pci = msg->crit_exts.rrc_conn_reest_request_r8().ue_id.pci;
const enb_cell_common* old_cell = parent->cell_common_list->get_pci(old_pci);
auto ue_it = parent->users.find(old_rnti);
auto old_ue_it = parent->users.find(old_rnti);
// Reject unrecognized rntis, and PCIs that do not belong to eNB
if (ue_it != parent->users.end() and old_cell != nullptr and
ue_it->second->ue_cell_list.get_enb_cc_idx(old_cell->enb_cc_idx) != nullptr) {
parent->logger.info("ConnectionReestablishmentRequest for rnti=0x%x. Sending Connection Reestablishment",
old_rnti);
if (old_ue_it == parent->users.end() or old_cell == nullptr or
old_ue_it->second->ue_cell_list.get_enb_cc_idx(old_cell->enb_cc_idx) == nullptr) {
parent->logger.error("Received ConnectionReestablishment for rnti=0x%x without context", old_rnti);
send_connection_reest_rej(procedure_result_code::error_unknown_rnti);
srsran::console(
"User 0x%x RRC Reestablishment Request rejected. Cause: no rnti=0x%x context available\n", rnti, old_rnti);
return;
}
ue* old_ue = old_ue_it->second.get();
// Reestablishment procedure going forward
parent->logger.info("ConnectionReestablishmentRequest for rnti=0x%x. Sending Connection Reestablishment", old_rnti);
srsran::console(
"User 0x%x requesting RRC Reestablishment as 0x%x. Cause: %s\n", rnti, old_rnti, req_r8.reest_cause.to_string());
// Cancel Handover in Target eNB if on-going
asn1::s1ap::cause_c cause;
cause.set_radio_network().value = asn1::s1ap::cause_radio_network_opts::interaction_with_other_proc;
parent->users.at(old_rnti)->mobility_handler->trigger(rrc_mobility::ho_cancel_ev{cause});
old_ue->mobility_handler->trigger(rrc_mobility::ho_cancel_ev{cause});
// Recover security setup
const enb_cell_common* pcell_cfg = get_ue_cc_cfg(UE_PCELL_CC_IDX);
ue_security_cfg = parent->users.at(old_rnti)->ue_security_cfg;
ue_security_cfg = old_ue->ue_security_cfg;
ue_security_cfg.regenerate_keys_handover(pcell_cfg->cell_cfg.pci, pcell_cfg->cell_cfg.dl_earfcn);
// send reestablishment and restore bearer configuration
send_connection_reest(parent->users.at(old_rnti)->ue_security_cfg.get_ncc());
// send RRC Reestablishment message and restore bearer configuration
send_connection_reest(old_ue->ue_security_cfg.get_ncc());
// Get PDCP entity state (required when using RLC AM)
for (const auto& erab_pair : parent->users.at(old_rnti)->bearer_list.get_erabs()) {
for (const auto& erab_pair : old_ue->bearer_list.get_erabs()) {
uint16_t lcid = erab_pair.second.id - 2;
old_reest_pdcp_state[lcid] = {};
parent->pdcp->get_bearer_state(old_rnti, lcid, &old_reest_pdcp_state[lcid]);
@ -576,34 +592,25 @@ void rrc::ue::handle_rrc_con_reest_req(rrc_conn_reest_request_s* msg)
}
// Make sure UE capabilities are copied over to new RNTI
eutra_capabilities = parent->users.at(old_rnti)->eutra_capabilities;
eutra_capabilities_unpacked = parent->users.at(old_rnti)->eutra_capabilities_unpacked;
ue_capabilities = parent->users.at(old_rnti)->ue_capabilities;
eutra_capabilities = old_ue->eutra_capabilities;
eutra_capabilities_unpacked = old_ue->eutra_capabilities_unpacked;
ue_capabilities = old_ue->ue_capabilities;
if (parent->logger.debug.enabled()) {
asn1::json_writer js{};
eutra_capabilities.to_json(js);
parent->logger.debug("rnti=0x%x EUTRA capabilities: %s", rnti, js.to_string().c_str());
}
if (parent->users.at(old_rnti)->rlc_rlf_timer.is_running()) {
parent->logger.info("Stopping RLC RLF timer for old rnti=0x%x", old_rnti);
parent->users.at(old_rnti)->rlc_rlf_timer.stop();
}
// Stop RLF timers to avoid that old RNTI gets removed during RRC Reestablishment
parent->logger.info("Stopped RLF timers for old rnti=0x%x", old_rnti);
old_ue->rlc_rlf_timer.stop();
old_ue->phy_ul_rlf_timer.stop();
old_ue->phy_dl_rlf_timer.stop();
old_ue->mac_ctrl.set_drb_activation(false);
old_reest_rnti = old_rnti;
state = RRC_STATE_WAIT_FOR_CON_REEST_COMPLETE;
set_activity_timeout(UE_INACTIVITY_TIMEOUT);
} else {
parent->logger.error("Received ConnectionReestablishment for rnti=0x%x without context", old_rnti);
send_connection_reest_rej(procedure_result_code::error_unknown_rnti);
srsran::console(
"User 0x%x RRC Reestablishment Request rejected. Cause: no rnti=0x%x context available\n", rnti, old_rnti);
}
} else {
parent->logger.error("Received ReestablishmentRequest from an rnti=0x%x not in IDLE", rnti);
send_connection_reest_rej(procedure_result_code::error_unknown_rnti);
srsran::console("ERROR: User 0x%x requesting Reestablishment is not in RRC_IDLE\n", rnti);
}
}
void rrc::ue::send_connection_reest(uint8_t ncc)
@ -658,6 +665,14 @@ void rrc::ue::handle_rrc_con_reest_complete(rrc_conn_reest_complete_s* msg, srsr
parent->logger.info("RRCConnectionReestablishComplete transaction ID: %d", msg->rrc_transaction_id);
auto old_ue_it = parent->users.find(old_reest_rnti);
if (old_ue_it == parent->users.end()) {
parent->logger.error("RRC Reestablishment old rnti=0x%x was erased during the procedure", old_reest_rnti);
parent->release_ue(rnti);
return;
}
auto* old_ue = old_ue_it->second.get();
// TODO: msg->selected_plmn_id - used to select PLMN from SIB1 list
// TODO: if(msg->registered_mme_present) - the indicated MME should be used from a pool
@ -674,10 +689,10 @@ void rrc::ue::handle_rrc_con_reest_complete(rrc_conn_reest_complete_s* msg, srsr
parent->pdcp->enable_encryption(rnti, srb_to_lcid(lte_srb::srb1));
// Reestablish E-RABs of old rnti during ConnectionReconfiguration
bearer_list.reestablish_bearers(std::move(parent->users.at(old_reest_rnti)->bearer_list));
bearer_list.reestablish_bearers(std::move(old_ue->bearer_list));
// remove old RNTI
parent->rem_user_thread(old_reest_rnti);
parent->rem_user(old_reest_rnti);
state = RRC_STATE_REESTABLISHMENT_COMPLETE;

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