diff options
authorNeels Hofmeyr <>2016-10-11 00:50:05 +0200
committerNeels Hofmeyr <>2016-11-12 16:06:46 +0100
commita5e8069cca887b28b91f2f2c328e5727bd5af48f (patch)
parent158559bef88ec70a60128e3c83b41e44eacf223a (diff)
IuCS: don't remove Iu conn until release
Don't remove the gsm_subscriber_connection without an Iu Release. From the 2G paradigm to close a subscriber connection as soon as nothing else is pending, osmo-cscn frequently calls msc_release_connection() to see whether a conn has anything pending, or discards it. In 3G however, we so far don't actively release IuCS connections from the MSC side, but wait until the IuCS is released from the UE side. So the conn is often discarded even though the IuCS stays open and valid, which confuses the situation: before the UE releases a bit later, we would try to page the subscriber unsuccessfully, because the UE expects to already be connected. To first fix the discrepancy of Iu vs. subscr release, never discard gsm_subscriber_connections when msc_release_connection() is called. This creates a "lazy" CN that keeps connections open as long as the UE will tolerate. It is really fast in sending many SMS in close succession, but is certainly a bad CN design choice: we should rather stay lean on connections. A subsequent commit will change this, but I decided to keep this commit as a reference, for when we'd like to test situations that should re-use an established connection. Change-Id: I012378cfa432d791146db387554ec1909de05297
1 files changed, 4 insertions, 0 deletions
diff --git a/openbsc/src/libmsc/osmo_msc.c b/openbsc/src/libmsc/osmo_msc.c
index 6e982d050..2d5f94b56 100644
--- a/openbsc/src/libmsc/osmo_msc.c
+++ b/openbsc/src/libmsc/osmo_msc.c
@@ -149,6 +149,10 @@ struct bsc_api *msc_bsc_api() {
/* conn release handling */
void msc_release_connection(struct gsm_subscriber_connection *conn)
+ /* For IuCS, always wait until the UE releases. */
+ if (conn->via_iface == IFACE_IU)
+ return;
/* skip when we are in release, e.g. due an error */
if (conn->in_release)