diff --git a/epdg/EPDG_Tests.ttcn b/epdg/EPDG_Tests.ttcn
index 1742fd7..f963994 100644
--- a/epdg/EPDG_Tests.ttcn
+++ b/epdg/EPDG_Tests.ttcn
@@ -472,7 +472,8 @@
 }
 
 /* Send PPR as HSS to AAA server, expect back PPA */
-private function f_DIA_SWx_PP(template (present) GenericAVP exp_result_tmpl := tr_AVP_ResultCode(DIAMETER_SUCCESS)) runs on EPDG_ConnHdlr {
+private function f_DIA_SWx_PP(template (present) GenericAVP exp_result_tmpl := tr_AVP_ResultCode(DIAMETER_SUCCESS),
+			      boolean exp_aaa_proc := true) runs on EPDG_ConnHdlr {
 	var PDU_DIAMETER rx_dia;
 	var UINT32 hbh_id := f_rnd_octstring(4);
 	var UINT32 ete_id := f_rnd_octstring(4);
@@ -489,6 +490,24 @@
 				hbh_id := hbh_id,
 				ete_id := ete_id));
 
+	if (exp_aaa_proc) {
+		/* TODO: in successful case, we want to validate how this procedure extends to other interfaces:
+		* """ 3GPP TS 29.273 8.1.2.3.3:
+		* After a successful user profile download, the 3GPP AAA Server shall
+		* initiate re-authentication procedure as described
+		* in clause 7.2.2.4 if the subscriber has previously been authenticated
+		* and authorized to untrusted non-3GPP access.
+		* """
+		*/
+		/* TS 29.273 9.1.2.5.1:
+		 * "The Service Authorization Information Update procedure is performed in two steps":
+		 * step 1: */
+		as_DIA_S6b_RA_success();
+		/* step 2 */
+		/* Since PGW Address didn't change, expect no SAR+SAA triggered as a consequence to AAR+AAA. */
+		f_S6b_AA_success(exp_swx_sa_proc := false);
+	}
+
 	alt {
 	[] SWx.receive(tr_DIA_SWx_PPA(exp_result_tmpl, hbh_id := hbh_id, ete_id := ete_id)) -> value rx_dia {}
 	[] SWx.receive(PDU_DIAMETER:?) -> value rx_dia {
@@ -536,7 +555,7 @@
 
 
 /* Send AAR as PGW to AAA server, expect back AAA */
-private function f_S6b_AA_success() runs on EPDG_ConnHdlr {
+private function f_S6b_AA_success(boolean exp_swx_sa_proc := true) runs on EPDG_ConnHdlr {
 	var PDU_DIAMETER rx_dia;
 	var UINT32 hbh_id := f_rnd_octstring(4);
 	var UINT32 ete_id := f_rnd_octstring(4);
@@ -555,8 +574,10 @@
 				pgw_addr,
 				hbh_id := hbh_id, ete_id := ete_id));
 
-	/* AAR in S6b in AAA-Server triggers Service-Assignment Request/Answer towards HSS: */
-	as_DIA_SWx_SA_success();
+	if (exp_swx_sa_proc) {
+		/* AAR in S6b in AAA-Server triggers Service-Assignment Request/Answer towards HSS: */
+		as_DIA_SWx_SA_success();
+	}
 
 	alt {
 	[] S6b.receive(tr_DIA_S6b_AAA) -> value rx_dia {}
@@ -587,6 +608,25 @@
 	}
 }
 
+/* Diameter S6b RAR + RAA, TS 29.273 9.1.2.5. */
+private altstep as_DIA_S6b_RA_success() runs on EPDG_ConnHdlr {
+	var PDU_DIAMETER rx_dia;
+	var template (omit) AVP avp;
+	var octetstring sess_id;
+	[] S6b.receive(tr_DIA_S6b_RAR(f_nai())) -> value rx_dia {
+		avp := f_DIAMETER_get_avp(rx_dia, c_AVP_Code_BASE_NONE_Session_Id);
+		sess_id := valueof(avp.avp_data.avp_BASE_NONE_Session_Id);
+		S6b.send(ts_DIA_S6b_RAA(DIAMETER_SUCCESS,
+					sess_id := sess_id,
+					hbh_id := rx_dia.hop_by_hop_id,
+					ete_id := rx_dia.end_to_end_id));
+		setverdict(pass);
+	}
+	[] S6b.receive(PDU_DIAMETER:?) -> value rx_dia {
+		Misc_Helpers.f_shutdown(__BFILE__, __LINE__, fail, log2str("Unexpected Diameter S6b msg rx: ", rx_dia));
+	}
+}
+
 /* Diameter S6b ASR + ASA, TS 29.273 9.1.2.3.4. */
 private altstep as_DIA_S6b_AS_success() runs on EPDG_ConnHdlr {
 	var PDU_DIAMETER rx_dia;
@@ -602,7 +642,7 @@
 		setverdict(pass);
 	}
 	[] S6b.receive(PDU_DIAMETER:?) -> value rx_dia {
-		Misc_Helpers.f_shutdown(__BFILE__, __LINE__, fail, log2str("Unexpected Diameter msg rx: ", rx_dia));
+		Misc_Helpers.f_shutdown(__BFILE__, __LINE__, fail, log2str("Unexpected Diameter S6b msg rx: ", rx_dia));
 	}
 }
 
@@ -1188,7 +1228,8 @@
  */
 private function f_TC_hss_initiated_update_user_profile_unknown(charstring id) runs on EPDG_ConnHdlr {
 	var DIAMETER_ts29_229_ExperimentalResultcode erc := DIAMETER_ERROR_USER_UNKNOWN;
-	f_DIA_SWx_PP(tr_AVP_ExperimentalResult(vendor_id_3GPP, int2oct(enum2int(erc), 4)));
+	f_DIA_SWx_PP(tr_AVP_ExperimentalResult(vendor_id_3GPP, int2oct(enum2int(erc), 4)),
+		     exp_aaa_proc := false);
 }
 testcase TC_hss_initiated_update_user_profile_unknown() runs on MTC_CT {
 	var EPDG_ConnHdlrPars pars := f_init_pars();
diff --git a/library/DIAMETER_Templates.ttcn b/library/DIAMETER_Templates.ttcn
index 933c97b..7148513 100644
--- a/library/DIAMETER_Templates.ttcn
+++ b/library/DIAMETER_Templates.ttcn
@@ -1144,6 +1144,23 @@
 	}
 }
 
+/* RFC6733 8.12. Re-Auth-Request-Type AVP */
+template (value) GenericAVP ts_AVP_ReAuthRequestType(BASE_NONE_Re_Auth_Request_Type reauth_req_type) := {
+	avp := {
+		avp_header := ts_DIA_Hdr(c_AVP_Code_BASE_NONE_Re_Auth_Request_Type, '00000000'B),
+		avp_data := {
+			avp_BASE_NONE_Re_Auth_Request_Type := reauth_req_type
+		}
+	}
+}
+template (present) GenericAVP tr_AVP_ReAuthRequestType(template (present) BASE_NONE_Re_Auth_Request_Type reauth_req_type) := {
+	avp := {
+		avp_header := tr_DIA_Hdr(c_AVP_Code_BASE_NONE_Re_Auth_Request_Type),
+		avp_data := {
+			avp_BASE_NONE_Re_Auth_Request_Type := reauth_req_type
+		}
+	}
+}
 
 /* 5.3.1 Capabilities Exchange Request */
 template (value) PDU_DIAMETER
diff --git a/library/DIAMETER_ts29_273_Templates.ttcn b/library/DIAMETER_ts29_273_Templates.ttcn
index dcb5a31..6ed00ff 100644
--- a/library/DIAMETER_ts29_273_Templates.ttcn
+++ b/library/DIAMETER_ts29_273_Templates.ttcn
@@ -623,4 +623,55 @@
 			ts_AVP_OriginRealm(orig_realm)
 	});
 
+/* TS 29.273 9.2.2.6.1 Re-Auth-Request (RAR)
+ * TS 29.273  Table 9.1.2.5.1/1: S6b Re-authorization request */
+template (present) PDU_DIAMETER
+tr_DIA_S6b_RAR(template (present) charstring username_nai := ?,
+	       template (present) octetstring sess_id := ?,
+	       template (present) charstring orig_host := ?,
+	       template (present) charstring orig_realm := ?,
+	       template (present) charstring dest_realm := ?,
+	       template (present) charstring dest_host := ?,
+	       template (present) UINT32 hbh_id := ?,
+	       template (present) UINT32 ete_id := ?) :=
+	tr_DIAMETER(flags := '1???????'B,
+		    cmd_code := Re_Auth,
+		    app_id := int2oct(c_DIAMETER_3GPP_S6b_AID, 4),
+		    hbh_id := hbh_id,
+		    ete_id := ete_id,
+		    avps := superset(
+			tr_AVP_SessionId(sess_id),
+			/* Optional: DRMP, */
+			tr_AVP_OriginHost(orig_host),
+			tr_AVP_OriginRealm(orig_realm),
+			tr_AVP_DestinationRealm(dest_realm),
+			tr_AVP_DestinationHost(dest_host),
+			tr_AVP_AuthAppId(int2oct(c_DIAMETER_3GPP_S6b_AID, 4)),
+			tr_AVP_ReAuthRequestType(AUTHORIZE_ONLY),
+			tr_AVP_UserName(char2oct_tmpl_present(username_nai))
+			/* Optional: RAR-Flags, */
+	));
+
+/* TS 29.273 9.2.2.6.2 Re-Auth-Answer (RAA)
+ * TS 29.273 Table 9.1.2.5.1/2: S6b Re-authorization response */
+template (value) PDU_DIAMETER
+ts_DIA_S6b_RAA(template (value) DIAMETER_Resultcode res_code := DIAMETER_SUCCESS,
+	       template (value) octetstring sess_id := c_def_sess_id,
+	       template (value) charstring orig_host := "aaa.localdomain",
+	       template (value) charstring orig_realm := "localdomain",
+	       template (value) charstring dest_realm := "localdomain",
+	       template (value) UINT32 hbh_id := '00000000'O,
+	       template (value) UINT32 ete_id := '00000000'O) :=
+	ts_DIAMETER(flags := '01000000'B,
+		    cmd_code := Re_Auth,
+		    app_id := int2oct(c_DIAMETER_3GPP_S6b_AID, 4),
+		    hbh_id := hbh_id, ete_id := ete_id,
+		    avps := {
+			ts_AVP_SessionId(sess_id),
+			/* Optional: DRMP, */
+			ts_AVP_ResultCode(res_code),
+			ts_AVP_OriginHost(orig_host),
+			ts_AVP_OriginRealm(orig_realm)
+	});
+
 }