Change in osmo-bsc[master]: MSC pooling: add 'no allow-attach' for MSC off-loading

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neels gerrit-no-reply at lists.osmocom.org
Thu Jun 11 01:35:11 UTC 2020


neels has uploaded this change for review. ( https://gerrit.osmocom.org/c/osmo-bsc/+/18778 )


Change subject: MSC pooling: add 'no allow-attach' for MSC off-loading
......................................................................

MSC pooling: add 'no allow-attach' for MSC off-loading

As in 3GPP TS 23.236, to offload an MSC, the BSC must be able to avoid
attaching new subscribers to it:

4.5a.1: "UEs being moved from one CN node are stopped from registering to the
same CN node again by an O&M command in BSCs and RNCs connected to the pool."

Change-Id: I6249201c15d0f6565aca643c21d2375c9ca58584
---
M include/osmocom/bsc/bsc_msc_data.h
M src/osmo-bsc/gsm_08_08.c
M src/osmo-bsc/osmo_bsc_msc.c
M src/osmo-bsc/osmo_bsc_vty.c
M tests/nri_cfg.vty
5 files changed, 48 insertions(+), 1 deletion(-)



  git pull ssh://gerrit.osmocom.org:29418/osmo-bsc refs/changes/78/18778/1

diff --git a/include/osmocom/bsc/bsc_msc_data.h b/include/osmocom/bsc/bsc_msc_data.h
index 3df2774..fc6c2d6 100644
--- a/include/osmocom/bsc/bsc_msc_data.h
+++ b/include/osmocom/bsc/bsc_msc_data.h
@@ -181,6 +181,7 @@
 	} mgcp_ipa;
 
 	struct osmo_nri_ranges *nri_ranges;
+	bool allow_attach;
 };
 
 int osmo_bsc_msc_init(struct bsc_msc_data *msc);
diff --git a/src/osmo-bsc/gsm_08_08.c b/src/osmo-bsc/gsm_08_08.c
index 0707c65..0064b41 100644
--- a/src/osmo-bsc/gsm_08_08.c
+++ b/src/osmo-bsc/gsm_08_08.c
@@ -231,7 +231,11 @@
 
 		/* Figure out the next round-robin MSC. The MSCs may appear unsorted in net->mscs. Make sure to linearly
 		 * round robin the MSCs by number: pick the lowest msc->nr >= round_robin_next_nr, and also remember the
-		 * lowest available msc->nr to wrap back to that in case no next MSC is left. */
+		 * lowest available msc->nr to wrap back to that in case no next MSC is left.
+		 * MSCs configured with `no allow-attach` do not accept new subscribers and hence must not be picked by
+		 * round-robin. */
+		if (!msc->allow_attach)
+			continue;
 		if (!msc_round_robin_first || msc->nr < msc_round_robin_first->nr)
 			msc_round_robin_first = msc;
 		if (msc->nr >= round_robin_next_nr
diff --git a/src/osmo-bsc/osmo_bsc_msc.c b/src/osmo-bsc/osmo_bsc_msc.c
index ce07518..157808e 100644
--- a/src/osmo-bsc/osmo_bsc_msc.c
+++ b/src/osmo-bsc/osmo_bsc_msc.c
@@ -230,6 +230,7 @@
 	msc_data->mgcp_ipa.local_port = 0; /* dynamic */
 
 	msc_data->nri_ranges = osmo_nri_ranges_alloc(msc_data);
+	msc_data->allow_attach = true;
 
 	return msc_data;
 }
diff --git a/src/osmo-bsc/osmo_bsc_vty.c b/src/osmo-bsc/osmo_bsc_vty.c
index 7db7c94..dbdd807 100644
--- a/src/osmo-bsc/osmo_bsc_vty.c
+++ b/src/osmo-bsc/osmo_bsc_vty.c
@@ -177,6 +177,9 @@
 	}
 
 	msc_write_nri(vty, msc, false);
+
+	if (!msc->allow_attach)
+		vty_out(vty, " no allow-attach%s", VTY_NEWLINE);
 }
 
 static int config_write_msc(struct vty *vty)
@@ -861,6 +864,28 @@
 	return CMD_SUCCESS;
 }
 
+DEFUN(cfg_msc_allow_attach, cfg_msc_allow_attach_cmd,
+      "allow-attach",
+      "Allow this MSC to attach new subscribers (default).\n")
+{
+	struct bsc_msc_data *msc = bsc_msc_data(vty);
+	msc->allow_attach = true;
+	return CMD_SUCCESS;
+}
+
+DEFUN(cfg_msc_no_allow_attach, cfg_msc_no_allow_attach_cmd,
+      "no allow-attach",
+      NO_STR
+      "Do not assign new subscribers to this MSC."
+      " Useful if an MSC in an MSC pool is configured to off-load subscribers."
+      " The MSC will still be operational for already attached subscribers,"
+      " but the NAS node selection function will skip this MSC for new subscribers\n")
+{
+	struct bsc_msc_data *msc = bsc_msc_data(vty);
+	msc->allow_attach = false;
+	return CMD_SUCCESS;
+}
+
 static void msc_write_nri(struct vty *vty, struct bsc_msc_data *msc, bool verbose)
 {
 	struct osmo_nri_range *r;
@@ -964,6 +989,8 @@
 	install_element(MSC_NODE, &cfg_msc_nri_add_cmd);
 	install_element(MSC_NODE, &cfg_msc_nri_del_cmd);
 	install_element(MSC_NODE, &cfg_msc_show_nri_cmd);
+	install_element(MSC_NODE, &cfg_msc_allow_attach_cmd);
+	install_element(MSC_NODE, &cfg_msc_no_allow_attach_cmd);
 
 	/* Deprecated: ping time config, kept to support legacy config files. */
 	install_element(MSC_NODE, &cfg_net_msc_no_ping_time_cmd);
diff --git a/tests/nri_cfg.vty b/tests/nri_cfg.vty
index 2b38ec4..3ab7bf2 100644
--- a/tests/nri_cfg.vty
+++ b/tests/nri_cfg.vty
@@ -159,3 +159,17 @@
 OsmoBSC(config-msc)# show nri
 msc 0
  nri add 0 1000
+
+OsmoBSC(config-msc)# show running-config
+... ! no allow-attach
+OsmoBSC(config-msc)# no allow-attach
+OsmoBSC(config-msc)# show running-config
+...
+msc 0
+...
+ nri add 0 1000
+ no allow-attach
+... ! no allow-attach
+OsmoBSC(config-msc)# allow-attach
+OsmoBSC(config-msc)# show running-config
+... ! no allow-attach

-- 
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Gerrit-Project: osmo-bsc
Gerrit-Branch: master
Gerrit-Change-Id: I6249201c15d0f6565aca643c21d2375c9ca58584
Gerrit-Change-Number: 18778
Gerrit-PatchSet: 1
Gerrit-Owner: neels <nhofmeyr at sysmocom.de>
Gerrit-MessageType: newchange
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