Change in osmo-ttcn3-hacks[master]: msc: inter-BSC HO test: use CGI cell ID, not LAI

neels gerrit-no-reply at lists.osmocom.org
Wed Jun 23 01:57:06 UTC 2021


neels has uploaded this change for review. ( https://gerrit.osmocom.org/c/osmo-ttcn3-hacks/+/24748 )


Change subject: msc: inter-BSC HO test: use CGI cell ID, not LAI
......................................................................

msc: inter-BSC HO test: use CGI cell ID, not LAI

In the inter-BSC 'Handover Required', do not send a LAI cell identifier,
but a CGI one.

Rationale:

As explained in OS#5188, 3GPP TS 48.008 allows a LAI identification only
in the Cell Identifier List IE, but not in the single Cell Identifier
IE.

In the inter-BSC HO test's Handover Required message, we so far send a
LAI identifier in a List IE to osmo-msc. And so far, osmo-msc simply
echos that in the Handover Request message's single Cell Id IE.

The LAI is, as actually defined in the spec, omitted from the single IE
in deps/titan.ProtocolModules.BSSMAP/src/BSSAP_Types.ttcn, and when
osmo-msc sends the non-standard LAI Id, ttcn3 fails to parse the BSSMAP
Handover Request message: the Cell Identifier IE gets wrong values, and
all remaining IEs are parsed as 'omit' even though they are present on
the wire. So as long as osmo-msc sends back a LAI Id, we cannot sanely
verify the Handover Request received from the MSC.

The CGI identifier type is supported in both IEs. So when the test sends
a CGI identifier in the Handover Required, osmo-msc will also reflect a
CGI identifier in the Handover Request, and ttcn3 parsing works.

This prepares for adding verification of the ciphering in inter-BSC
handover, in turn a preparation for adding tests of A5/4.

Related: OS#5188 SYS#5324
Change-Id: I48276acf923626db171683dfa03ef43614a71380
---
M msc/MSC_Tests.ttcn
1 file changed, 3 insertions(+), 3 deletions(-)



  git pull ssh://gerrit.osmocom.org:29418/osmo-ttcn3-hacks refs/changes/48/24748/1

diff --git a/msc/MSC_Tests.ttcn b/msc/MSC_Tests.ttcn
index b791782..e37bc52 100644
--- a/msc/MSC_Tests.ttcn
+++ b/msc/MSC_Tests.ttcn
@@ -5721,7 +5721,7 @@
 	f_vty_transceive(MSCVTY, "configure terminal");
 	f_vty_transceive(MSCVTY, "msc");
 	f_vty_transceive(MSCVTY, "neighbor a cgi 262 42 23 42 ran-pc 0.24.1");
-	f_vty_transceive(MSCVTY, "neighbor a lac 5 ran-pc 0.24.2");
+	f_vty_transceive(MSCVTY, "neighbor a cgi 023 42 5 6 ran-pc 0.24.2");
 	f_vty_transceive(MSCVTY, "exit");
 	f_vty_transceive(MSCVTY, "exit");
 
@@ -5736,7 +5736,7 @@
 	var BssmapCause cause := enum2int(cause_val);
 
 	var template BSSMAP_FIELD_CellIdentificationList cil;
-	cil := { cIl_LAI := { ts_BSSMAP_CI_LAI('023'H, '42'H, 5) } };
+	cil := { cIl_CGI := { ts_BSSMAP_CI_CGI('023'H, '42'H, 5, 6) } };
 
 	/* old BSS sends Handover Required */
 	BSSAP.send(ts_BSSMAP_HandoverRequired(cause, cil));
@@ -5841,7 +5841,7 @@
 	var BssmapCause cause := enum2int(cause_val);
 
 	var template BSSMAP_FIELD_CellIdentificationList cil;
-	cil := { cIl_LAI := { ts_BSSMAP_CI_LAI('262'H, '42'H, 23) } };
+	cil := { cIl_CGI := { ts_BSSMAP_CI_CGI('262'H, '42'H, 23, 42) } };
 
 	/* old BSS sends Handover Required */
 	BSSAP.send(ts_BSSMAP_HandoverRequired(cause, cil));

-- 
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Gerrit-Project: osmo-ttcn3-hacks
Gerrit-Branch: master
Gerrit-Change-Id: I48276acf923626db171683dfa03ef43614a71380
Gerrit-Change-Number: 24748
Gerrit-PatchSet: 1
Gerrit-Owner: neels <nhofmeyr at sysmocom.de>
Gerrit-MessageType: newchange
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