large refactoring: support inter-BSC and inter-MSC Handover
3GPP TS 49.008 '4.3 Roles of MSC-A, MSC-I and MSC-T' defines distinct roles:
- MSC-A is responsible for managing subscribers,
- MSC-I is the gateway to the RAN.
- MSC-T is a second transitory gateway to another RAN during Handover.
After inter-MSC Handover, the MSC-I is handled by a remote MSC instance, while
the original MSC-A retains the responsibility of subscriber management.
MSC-T exists in this patch but is not yet used, since Handover is only prepared
for, not yet implemented.
Facilitate Inter-MSC and inter-BSC Handover by the same internal split of MSC
roles.
Compared to inter-MSC Handover, mere inter-BSC has the obvious simplifications:
- all of MSC-A, MSC-I and MSC-T roles will be served by the same osmo-msc
instance,
- messages between MSC-A and MSC-{I,T} don't need to be routed via E-interface
(GSUP),
- no call routing between MSC-A and -I via MNCC necessary.
This is the largest code bomb I have submitted, ever. Out of principle, I
apologize to everyone trying to read this as a whole. Unfortunately, I see no
sense in trying to split this patch into smaller bits. It would be a huge
amount of work to introduce these changes in separate chunks, especially if
each should in turn be useful and pass all test suites. So, unfortunately, we
are stuck with this code bomb.
The following are some details and rationale for this rather huge refactoring:
* separate MSC subscriber management from ran_conn
struct ran_conn is reduced from the pivotal subscriber management entity it has
been so far to a mere storage for an SCCP connection ID and an MSC subscriber
reference.
The new pivotal subscriber management entity is struct msc_a -- struct msub
lists the msc_a, msc_i, msc_t roles, the vast majority of code paths however
use msc_a, since MSC-A is where all the interesting stuff happens.
Before handover, msc_i is an FSM implementation that encodes to the local
ran_conn. After inter-MSC Handover, msc_i is a compatible but different FSM
implementation that instead forwards via/from GSUP. Same goes for the msc_a
struct: if osmo-msc is the MSC-I "RAN proxy" for a remote MSC-A role, the
msc_a->fi is an FSM implementation that merely forwards via/from GSUP.
* New SCCP implementation for RAN access
To be able to forward BSSAP and RANAP messages via the GSUP interface, the
individual message layers need to be cleanly separated. The IuCS implementation
used until now (iu_client from libosmo-ranap) did not provide this level of
separation, and needed a complete rewrite. It was trivial to implement this in
such a way that both BSSAP and RANAP can be handled by the same SCCP code,
hence the new SCCP-RAN layer also replaces BSSAP handling.
sccp_ran.h: struct sccp_ran_inst provides an abstract handler for incoming RAN
connections. A set of callback functions provides implementation specific
details.
* RAN Abstraction (BSSAP vs. RANAP)
The common SCCP implementation did set the theme for the remaining refactoring:
make all other MSC code paths entirely RAN-implementation-agnostic.
ran_infra.c provides data structures that list RAN implementation specifics,
from logging to RAN de-/encoding to SCCP callbacks and timers. A ran_infra
pointer hence allows complete abstraction of RAN implementations:
- managing connected RAN peers (BSC, RNC) in ran_peer.c,
- classifying and de-/encoding RAN PDUs,
- recording connected LACs and cell IDs and sending out Paging requests to
matching RAN peers.
* RAN RESET now also for RANAP
ran_peer.c absorbs the reset_fsm from a_reset.c; in consequence, RANAP also
supports proper RESET semantics now. Hence osmo-hnbgw now also needs to provide
proper RESET handling, which it so far duly ignores. (TODO)
* RAN de-/encoding abstraction
The RAN abstraction mentioned above serves not only to separate RANAP and BSSAP
implementations transparently, but also to be able to optionally handle RAN on
distinct levels. Before Handover, all RAN messages are handled by the MSC-A
role. However, after an inter-MSC Handover, a standalone MSC-I will need to
decode RAN PDUs, at least in order to manage Assignment of RTP streams between
BSS/RNC and MNCC call forwarding.
ran_msg.h provides a common API with abstraction for:
- receiving events from RAN, i.e. passing RAN decode from the BSC/RNC and
MS/UE: struct ran_dec_msg represents RAN messages decoded from either BSSMAP
or RANAP;
- sending RAN events: ran_enc_msg is the counterpart to compose RAN messages
that should be encoded to either BSSMAP or RANAP and passed down to the
BSC/RNC and MS/UE.
The RAN-specific implementations are completely contained by ran_msg_a.c and
ran_msg_iu.c.
In particular, Assignment and Ciphering have so far been distinct code paths
for BSSAP and RANAP, with switch(via_ran){...} statements all over the place.
Using RAN_DEC_* and RAN_ENC_* abstractions, these are now completely unified.
Note that SGs does not qualify for RAN abstraction: the SGs interface always
remains with the MSC-A role, and SGs messages follow quite distinct semantics
from the fairly similar GERAN and UTRAN.
* MGW and RTP stream management
So far, managing MGW endpoints via MGCP was tightly glued in-between
GSM-04.08-CC on the one and MNCC on the other side. Prepare for switching RTP
streams between different RAN peers by moving to object-oriented
implementations: implement struct call_leg and struct rtp_stream with distinct
FSMs each. For MGW communication, use the osmo_mgcpc_ep API that has originated
from osmo-bsc and recently moved to libosmo-mgcp-client for this purpose.
Instead of implementing a sequence of events with code duplication for the RAN
and CN sides, the idea is to manage each RTP stream separately by firing and
receiving events as soon as codecs and RTP ports are negotiated, and letting
the individual FSMs take care of the MGW management "asynchronously". The
caller provides event IDs and an FSM instance that should be notified of RTP
stream setup progress. Hence it becomes possible to reconnect RTP streams from
one GSM-04.08-CC to another (inter-BSC Handover) or between CC and MNCC RTP
peers (inter-MSC Handover) without duplicating the MGCP code for each
transition.
The number of FSM implementations used for MGCP handling may seem a bit of an
overkill. But in fact, the number of perspectives on RTP forwarding are far
from trivial:
- an MGW endpoint is an entity with N connections, and MGCP "sessions" for
configuring them by talking to the MGW;
- an RTP stream is a remote peer connected to one of the endpoint's
connections, which is asynchronously notified of codec and RTP port choices;
- a call leg is the higher level view on either an MT or MO side of a voice
call, a combination of two RTP streams to forward between two remote peers.
BSC MGW PBX
CI CI
[MGW-endpoint]
[--rtp_stream--] [--rtp_stream--]
[----------------call_leg----------------]
* Use counts
Introduce using the new osmo_use_count API added to libosmocore for this
purpose. Each use token has a distinct name in the logging, which can be a
globally constant name or ad-hoc, like the local __func__ string constant. Use
in the new struct msc_a, as well as change vlr_subscr to the new osmo_use_count
API.
* FSM Timeouts
Introduce using the new osmo_tdef API, which provides a common VTY
implementation for all timer numbers, and FSM state transitions with the
correct timeout. Originated in osmo-bsc, recently moved to libosmocore.
Depends: Ife31e6798b4e728a23913179e346552a7dd338c0 (libosmocore)
Ib9af67b100c4583342a2103669732dab2e577b04 (libosmocore)
Id617265337f09dfb6ddfe111ef5e578cd3dc9f63 (libosmocore)
Ie9e2add7bbfae651c04e230d62e37cebeb91b0f5 (libosmo-sccp)
I26be5c4b06a680f25f19797407ab56a5a4880ddc (osmo-mgw)
Ida0e59f9a1f2dd18efea0a51680a67b69f141efa (osmo-mgw)
I9a3effd38e72841529df6c135c077116981dea36 (osmo-mgw)
Change-Id: I27e4988e0371808b512c757d2b52ada1615067bd
diff --git a/src/libmsc/msc_i.c b/src/libmsc/msc_i.c
new file mode 100644
index 0000000..6badba6
--- /dev/null
+++ b/src/libmsc/msc_i.c
@@ -0,0 +1,383 @@
+/* Code to manage a subscriber's MSC-I role */
+/*
+ * (C) 2019 by sysmocom - s.m.f.c. GmbH <info@sysmocom.de>
+ * All Rights Reserved
+ *
+ * SPDX-License-Identifier: AGPL-3.0+
+ *
+ * Author: Neels Hofmeyr
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <osmocom/msc/gsm_data.h>
+#include <osmocom/msc/msc_i.h>
+#include <osmocom/msc/ran_msg.h>
+#include <osmocom/msc/ran_conn.h>
+#include <osmocom/msc/ran_peer.h>
+#include <osmocom/msc/sccp_ran.h>
+#include <osmocom/msc/msub.h>
+#include <osmocom/msc/msc_a.h>
+#include <osmocom/msc/call_leg.h>
+#include <osmocom/msc/mncc_call.h>
+
+static struct osmo_fsm msc_i_fsm;
+
+struct ran_infra *msc_i_ran(struct msc_i *msc_i)
+{
+ OSMO_ASSERT(msc_i
+ && msc_i->ran_conn
+ && msc_i->ran_conn->ran_peer
+ && msc_i->ran_conn->ran_peer->sri
+ && msc_i->ran_conn->ran_peer->sri->ran);
+ return msc_i->ran_conn->ran_peer->sri->ran;
+}
+
+static int msc_i_ran_enc(struct msc_i *msc_i, const struct ran_msg *ran_enc_msg)
+{
+ struct msgb *l3 = msc_role_ran_encode(msc_i->c.fi, ran_enc_msg);
+ if (!l3)
+ return -EIO;
+ return msc_i_down_l2(msc_i, l3);
+}
+
+struct msc_i *msc_i_priv(struct osmo_fsm_inst *fi)
+{
+ OSMO_ASSERT(fi);
+ OSMO_ASSERT(fi->fsm == &msc_i_fsm);
+ OSMO_ASSERT(fi->priv);
+ return fi->priv;
+}
+
+int msc_i_ready_decode_cb(struct osmo_fsm_inst *msc_i_fi, void *data, const struct ran_msg *msg)
+{
+ struct msc_i *msc_i = msc_i_priv(msc_i_fi);
+ struct msc_a *msc_a = msub_msc_a(msc_i->c.msub);
+ const struct an_apdu *an_apdu = data;
+ uint32_t event;
+
+ event = MSC_A_EV_FROM_I_PROCESS_ACCESS_SIGNALLING_REQUEST;
+
+ switch (msg->msg_type) {
+ case RAN_MSG_HANDOVER_REQUIRED:
+ if (msc_a->c.remote_to) {
+ /* We're already a remote MSC-B, this hence must be a "subsequent" handover.
+ * There is not much difference really from dispatching a Process Access Signalling Request,
+ * only that 3GPP TS 29.010 specifies the different message type. */
+ event = MSC_A_EV_FROM_I_PREPARE_SUBSEQUENT_HANDOVER_REQUEST;
+ }
+ break;
+ default:
+ break;
+ }
+
+ return msub_role_dispatch(msc_i->c.msub, MSC_ROLE_A, event, an_apdu);
+}
+
+void msc_i_fsm_ready(struct osmo_fsm_inst *fi, uint32_t event, void *data)
+{
+ struct msc_i *msc_i = msc_i_priv(fi);
+ struct msc_a *msc_a = msub_msc_a(msc_i->c.msub);
+ struct an_apdu *an_apdu;
+
+ if (!msc_a) {
+ LOG_MSC_I(msc_i, LOGL_ERROR, "No MSC-A role\n");
+ return;
+ }
+
+ switch (event) {
+
+ case MSC_EV_FROM_RAN_COMPLETE_LAYER_3:
+ an_apdu = data;
+ msub_role_dispatch(msc_i->c.msub, MSC_ROLE_A, MSC_A_EV_FROM_I_COMPLETE_LAYER_3, an_apdu);
+ break;
+
+ case MSC_EV_FROM_RAN_UP_L2:
+ an_apdu = data;
+ /* To send the correct event types like MSC_A_EV_FROM_I_PREPARE_SUBSEQUENT_HANDOVER_REQUEST and hence
+ * reflect the correct GSUP message type on an inter-MSC link, need to decode the message here. */
+ msc_role_ran_decode(msc_i->c.fi, an_apdu, msc_i_ready_decode_cb, an_apdu);
+ break;
+
+ case MSC_EV_FROM_RAN_CONN_RELEASED:
+ msc_i_cleared(msc_i);
+ break;
+
+ case MSC_EV_CALL_LEG_TERM:
+ msc_i->inter_msc.call_leg = NULL;
+ if (msc_i->inter_msc.mncc_forwarding_to_remote_cn)
+ msc_i->inter_msc.mncc_forwarding_to_remote_cn->rtps = NULL;
+ break;
+
+ case MSC_MNCC_EV_CALL_ENDED:
+ msc_i->inter_msc.mncc_forwarding_to_remote_cn = NULL;
+ break;
+
+ case MSC_I_EV_FROM_A_FORWARD_ACCESS_SIGNALLING_REQUEST:
+ case MSC_I_EV_FROM_A_PREPARE_SUBSEQUENT_HANDOVER_RESULT:
+ case MSC_I_EV_FROM_A_PREPARE_SUBSEQUENT_HANDOVER_ERROR:
+ an_apdu = data;
+ if (an_apdu->an_proto != msc_i_ran(msc_i)->an_proto) {
+ LOG_MSC_I(msc_i, LOGL_ERROR, "Mismatching AN-APDU proto: %s -- Dropping message\n",
+ an_proto_name(an_apdu->an_proto));
+ msgb_free(an_apdu->msg);
+ an_apdu->msg = NULL;
+ return;
+ }
+ msc_i_down_l2(msc_i, an_apdu->msg);
+ break;
+
+ case MSC_I_EV_FROM_A_SEND_END_SIGNAL_RESPONSE:
+ msc_i_clear(msc_i);
+ break;
+
+ default:
+ OSMO_ASSERT(false);
+ }
+}
+
+void msc_i_fsm_clearing_onenter(struct osmo_fsm_inst *fi, uint32_t prev_state)
+{
+ struct msc_i *msc_i = msc_i_priv(fi);
+ struct ran_msg msg = {
+ .msg_type = RAN_MSG_CLEAR_COMMAND,
+ /* Concerning CSFB (Circuit-Switched FallBack from LTE), for a final Clear Command that might indicate
+ * CSFB, the MSC-A has to send the Clear Command. This Clear Command is about detaching an MSC-I when a
+ * new MSC-I has shown up after an inter-BSC or inter-MSC Handover succeeded. So never CSFB here. */
+ };
+ msc_i_ran_enc(msc_i, &msg);
+}
+
+int msc_i_clearing_decode_cb(struct osmo_fsm_inst *msc_i_fi, void *data, const struct ran_msg *msg)
+{
+ struct msc_i *msc_i = msc_i_fi->priv;
+
+ switch (msg->msg_type) {
+
+ case RAN_MSG_CLEAR_COMPLETE:
+ switch (msc_i->c.fi->state) {
+ case MSC_I_ST_CLEARING:
+ osmo_fsm_inst_state_chg(msc_i->c.fi, MSC_I_ST_CLEARED, 0, 0);
+ return 0;
+ case MSC_I_ST_CLEARED:
+ return 0;
+ default:
+ LOG_MSC_I(msc_i, LOGL_ERROR, "Received Clear Complete, but did not send Clear Command\n");
+ {
+ struct msc_a *msc_a = msub_msc_a(msc_i->c.msub);
+ if (msc_a)
+ osmo_fsm_inst_dispatch(msc_a->c.fi, MSC_A_EV_MO_CLOSE, NULL);
+ }
+ return 0;
+ }
+
+ default:
+ LOG_MSC_I(msc_i, LOGL_ERROR, "Message not handled: %s\n", ran_msg_type_name(msg->msg_type));
+ return -ENOTSUP;
+ }
+}
+
+void msc_i_fsm_clearing(struct osmo_fsm_inst *fi, uint32_t event, void *data)
+{
+ struct msc_i *msc_i = msc_i_priv(fi);
+ struct an_apdu *an_apdu;
+
+ /* We expect a Clear Complete and nothing else. */
+ switch (event) {
+ case MSC_EV_FROM_RAN_UP_L2:
+ an_apdu = data;
+ msc_role_ran_decode(msc_i->c.fi, an_apdu, msc_i_clearing_decode_cb, NULL);
+ return;
+
+ case MSC_EV_FROM_RAN_CONN_RELEASED:
+ msc_i_cleared(msc_i);
+ return;
+
+ case MSC_EV_CALL_LEG_TERM:
+ msc_i->inter_msc.call_leg = NULL;
+ if (msc_i->inter_msc.mncc_forwarding_to_remote_cn)
+ msc_i->inter_msc.mncc_forwarding_to_remote_cn->rtps = NULL;
+ break;
+
+ case MSC_MNCC_EV_CALL_ENDED:
+ msc_i->inter_msc.mncc_forwarding_to_remote_cn = NULL;
+ break;
+ }
+}
+
+void msc_i_fsm_cleared_onenter(struct osmo_fsm_inst *fi, uint32_t prev_state)
+{
+ osmo_fsm_inst_term(fi, OSMO_FSM_TERM_REGULAR, fi);
+}
+
+void msc_i_fsm_cleanup(struct osmo_fsm_inst *fi, enum osmo_fsm_term_cause cause)
+{
+ struct msc_i *msc_i = msc_i_priv(fi);
+
+ call_leg_release(msc_i->inter_msc.call_leg);
+ mncc_call_release(msc_i->inter_msc.mncc_forwarding_to_remote_cn);
+
+ if (msc_i->ran_conn)
+ ran_conn_msc_role_gone(msc_i->ran_conn, msc_i->c.fi);
+}
+
+#define S(x) (1 << (x))
+
+static const struct osmo_fsm_state msc_i_fsm_states[] = {
+ [MSC_I_ST_READY] = {
+ .name = "READY",
+ .action = msc_i_fsm_ready,
+ .in_event_mask = 0
+ | S(MSC_EV_FROM_RAN_COMPLETE_LAYER_3)
+ | S(MSC_EV_FROM_RAN_UP_L2)
+ | S(MSC_EV_FROM_RAN_CONN_RELEASED)
+ | S(MSC_EV_CALL_LEG_TERM)
+ | S(MSC_MNCC_EV_CALL_ENDED)
+ | S(MSC_I_EV_FROM_A_FORWARD_ACCESS_SIGNALLING_REQUEST)
+ | S(MSC_I_EV_FROM_A_PREPARE_SUBSEQUENT_HANDOVER_RESULT)
+ | S(MSC_I_EV_FROM_A_PREPARE_SUBSEQUENT_HANDOVER_ERROR)
+ | S(MSC_I_EV_FROM_A_SEND_END_SIGNAL_RESPONSE)
+ ,
+ .out_state_mask = 0
+ | S(MSC_I_ST_CLEARING)
+ | S(MSC_I_ST_CLEARED)
+ ,
+ },
+ [MSC_I_ST_CLEARING] = {
+ .name = "CLEARING",
+ .onenter = msc_i_fsm_clearing_onenter,
+ .action = msc_i_fsm_clearing,
+ .in_event_mask = 0
+ | S(MSC_EV_FROM_RAN_UP_L2)
+ | S(MSC_EV_FROM_RAN_CONN_RELEASED)
+ | S(MSC_EV_CALL_LEG_TERM)
+ | S(MSC_MNCC_EV_CALL_ENDED)
+ ,
+ .out_state_mask = 0
+ | S(MSC_I_ST_CLEARED)
+ ,
+ },
+ [MSC_I_ST_CLEARED] = {
+ .name = "CLEARED",
+ .onenter = msc_i_fsm_cleared_onenter,
+ },
+};
+
+const struct value_string msc_i_fsm_event_names[] = {
+ OSMO_VALUE_STRING(MSC_REMOTE_EV_RX_GSUP),
+ OSMO_VALUE_STRING(MSC_EV_CALL_LEG_RTP_LOCAL_ADDR_AVAILABLE),
+ OSMO_VALUE_STRING(MSC_EV_CALL_LEG_RTP_COMPLETE),
+ OSMO_VALUE_STRING(MSC_EV_CALL_LEG_RTP_RELEASED),
+ OSMO_VALUE_STRING(MSC_EV_CALL_LEG_TERM),
+ OSMO_VALUE_STRING(MSC_MNCC_EV_NEED_LOCAL_RTP),
+ OSMO_VALUE_STRING(MSC_MNCC_EV_CALL_PROCEEDING),
+ OSMO_VALUE_STRING(MSC_MNCC_EV_CALL_COMPLETE),
+ OSMO_VALUE_STRING(MSC_MNCC_EV_CALL_ENDED),
+
+ OSMO_VALUE_STRING(MSC_EV_FROM_RAN_COMPLETE_LAYER_3),
+ OSMO_VALUE_STRING(MSC_EV_FROM_RAN_UP_L2),
+ OSMO_VALUE_STRING(MSC_EV_FROM_RAN_CONN_RELEASED),
+
+ OSMO_VALUE_STRING(MSC_I_EV_FROM_A_FORWARD_ACCESS_SIGNALLING_REQUEST),
+ OSMO_VALUE_STRING(MSC_I_EV_FROM_A_PREPARE_SUBSEQUENT_HANDOVER_RESULT),
+ OSMO_VALUE_STRING(MSC_I_EV_FROM_A_PREPARE_SUBSEQUENT_HANDOVER_ERROR),
+ OSMO_VALUE_STRING(MSC_I_EV_FROM_A_SEND_END_SIGNAL_RESPONSE),
+ {}
+};
+
+static struct osmo_fsm msc_i_fsm = {
+ .name = "msc_i",
+ .states = msc_i_fsm_states,
+ .num_states = ARRAY_SIZE(msc_i_fsm_states),
+ .log_subsys = DMSC,
+ .event_names = msc_i_fsm_event_names,
+ .cleanup = msc_i_fsm_cleanup,
+};
+
+static __attribute__((constructor)) void msc_i_fsm_init(void)
+{
+ OSMO_ASSERT(osmo_fsm_register(&msc_i_fsm) == 0);
+}
+
+/* Send connection-oriented L3 message to RAN peer (MSC->[BSC|RNC]) */
+int msc_i_down_l2(struct msc_i *msc_i, struct msgb *l3)
+{
+ int rc;
+ if (!msc_i->ran_conn) {
+ LOG_MSC_I(msc_i, LOGL_ERROR, "Cannot Tx L2 message: no RAN conn\n");
+ return -EIO;
+ }
+
+ rc = ran_conn_down_l2_co(msc_i->ran_conn, l3, false);
+ if (rc)
+ LOG_MSC_I(msc_i, LOGL_ERROR, "Failed to transfer message down to subscriber (rc=%d)\n", rc);
+ return rc;
+}
+
+struct gsm_network *msc_i_net(const struct msc_i *msc_i)
+{
+ return msub_net(msc_i->c.msub);
+}
+
+struct vlr_subscr *msc_i_vsub(const struct msc_i *msc_i)
+{
+ return msub_vsub(msc_i->c.msub);
+}
+
+struct msc_i *msc_i_alloc(struct msub *msub, struct ran_infra *ran)
+{
+ return msub_role_alloc(msub, MSC_ROLE_I, &msc_i_fsm, struct msc_i, ran);
+}
+
+/* Send Clear Command and wait for Clear Complete autonomously. "Normally", the MSC-A handles Clear Command and receives
+ * Clear Complete, and then terminates MSC-I directly. This is useful to replace an MSC-I with another MSC-I during
+ * Handover. */
+void msc_i_clear(struct msc_i *msc_i)
+{
+ if (!msc_i)
+ return;
+ /* sanity timeout */
+ osmo_fsm_inst_state_chg(msc_i->c.fi, MSC_I_ST_CLEARING, 60, 0);
+}
+
+void msc_i_cleared(struct msc_i *msc_i)
+{
+ if (!msc_i)
+ return;
+ osmo_fsm_inst_state_chg(msc_i->c.fi, MSC_I_ST_CLEARED, 0, 0);
+}
+
+void msc_i_set_ran_conn(struct msc_i *msc_i, struct ran_conn *new_conn)
+{
+ struct ran_conn *old_conn = msc_i->ran_conn;
+
+ if (old_conn == new_conn)
+ return;
+
+ msc_i->ran_conn = NULL;
+ if (old_conn) {
+ old_conn->msc_role = NULL;
+ ran_conn_close(old_conn);
+ }
+
+ /* Taking a conn over from another MSC role? Make sure the other side forgets about it. */
+ if (new_conn->msc_role)
+ msc_role_forget_conn(new_conn->msc_role, new_conn);
+
+ msc_i->ran_conn = new_conn;
+ msc_i->ran_conn->msc_role = msc_i->c.fi;
+
+ /* Add the RAN conn info to the msub logging */
+ msub_update_id(msc_i->c.msub);
+}