4 General

29.3383GPPDiameter based protocols to support Short Message Service (SMS) capable Mobile Management Entities (MMEs)Release 18TS

4.1 Introduction

The SMS in MME architecture is described in 3GPP TS 23.272 [2] and the SMS in 5GS architecture is described in 3GPP TS 23.501 [21], have specified the reference points S6c and SGd.

The clause 4 addresses Diameter aspects which are common to S6c, SGd and Gdd.

4.2 Use of Diameter Base protocol

The Diameter base protocol as specified in IETF RFC 6733 [20] shall apply except as modified by the defined support of the methods and the defined support of the commands and AVPs, result and error codes as specified in this specification. Unless otherwise specified, the procedures (including error handling and unrecognised information handling) shall be used unmodified.

4.3 Securing Diameter messages

For secure transport of Diameter messages, see 3GPP TS 33.210 [11].

4.4 Accounting functionality

Accounting functionality (Accounting Session State Machine, related command codes and AVPs) shall not be used on the S6c, SGd and Gdd interfaces.

4.5 Use of sessions

Diameter sessions shall be implicitly terminated over the S6c, SGd and Gdd interfaces. An implicitly terminated session is one for which the server does not maintain state information. The client shall not send any re-authorization or session termination requests to the server.

The Diameter base protocol specified in IETF RFC 6733 [20] includes the Auth-Session-State AVP as the mechanism for the implementation of implicitly terminated sessions.

The client (server) shall include in its requests (responses) the Auth-Session-State AVP set to the value NO_STATE_MAINTAINED (1), as described in IETF RFC 6733 [20]. As a consequence, the server shall not maintain any state information about this session and the client shall not send any session termination request. Neither the Authorization-Lifetime AVP nor the Session-Timeout AVP shall be present in requests or responses.

4.6 Transport protocol

Diameter messages over the S6c, SGd and Gdd interfaces shall make use of SCTP as specified in IETF RFC 4960 [12] as transport protocol.

4.7 Advertising application support

The MME, HSS, SMS-IWMSC, SMS-GMSC and SMS Router shall advertise support of the Diameter S6c Application over the S6c interface and of the Diameter SGd Application over the SGd interface by including the value of the application identifier in the Auth-Application-Id AVP within the Vendor-Specific-Application-Id grouped AVP of the Capabilities-Exchange-Request and Capabilities-Exchange-Answer commands. The MME, SMS-GMSC and SMS Router shall additionally advertise support of the Diameter S6c Application over the SGd interface if they support the Alert Service Centre procedure between the MME, SMS-GMSC and SMS Router.

The SGSN, SMS-IWMSC, SMS-GMSC and SMS Router shall advertise support of the Diameter SGd Application over the Gdd interface by including the value of the application identifier in the Auth-Application-Id AVP within the Vendor-Specific-Application-Id grouped AVP of the Capabilities-Exchange-Request and Capabilities-Exchange-Answer commands. The SGSN, SMS-GMSC and SMS Router shall additionally advertise support of the Diameter S6c Application over the Gdd interface if they support the Alert Service Centre procedure between the SGSN, SMS-GMSC and SMS Router.

The MTC-IWF and SMS-IWMSC shall advertise support of the Diameter SGd Application over the T4 interface if they support the MO-Forward-Short-Message procedure between the SMS-IWMSC and the MTC-IWF.

The vendor identifier value of 3GPP (10415) shall be included in the Supported-Vendor-Id AVP of the Capabilities-Exchange-Request and Capabilities-Exchange-Answer commands, and in the Vendor-Id AVP within the Vendor-Specific-Application-Id grouped AVP of the Capabilities-Exchange-Request and Capabilities-Exchange-Answer commands.

The Vendor-Id AVP included in Capabilities-Exchange-Request and Capabilities-Exchange-Answer commands that is not included in the Vendor-Specific-Application-Id AVPs as described above shall indicate the manufacturer of the Diameter node as per IETF RFC 6733 [20].

4.8 Diameter Application Identifier

The S6c and the SGd/Gdd interface protocols shall be defined, each, as an IETF vendor specific Diameter application, where the vendor is 3GPP. The vendor identifier assigned by IANA to 3GPP (http://www.iana.org/assignments/enterprise-numbers) is 10415.

The Diameter application identifier assigned to the S6c Diameter application is 16777312 (allocated by IANA).

The Diameter application identifier assigned to the SGd Diameter application, which is also applicable to the Gdd and T4 interfaces is 16777313 (allocated by IANA).

4.9 Use of the Supported-Features AVP

When new functionality is introduced on the S6c or SGd Diameter applications, it should be defined as optional. If backwards incompatible changes can not be avoided, the new functionality shall be introduced as a new feature and support advertised with the Supported-Features AVP. The usage of the Supported-Features AVP on the S6c or SGd applications is consistent with the procedures for the dynamic discovery of supported features as defined in clause 7.2 of 3GPP TS 29.229 [5].

When extending the application by adding new AVPs for a feature, the new AVPs shall have the M bit cleared and the AVP shall not be defined mandatory in the command ABNF.

As defined in 3GPP TS 29.229 [5], the Supported-Features AVP is of type grouped and contains the Vendor-Id, Feature-List-ID and Feature-List AVPs. On the all reference points as specified in this specification, the Supported-Features AVP is used to identify features that have been defined by 3GPP and hence, for features defined in this document, the Vendor-Id AVP shall contain the vendor ID of 3GPP (10415). If there are multiple feature lists defined for the reference point, the Feature-List-ID AVP shall differentiate those lists from one another.

The Table 5.3.3.13/1 defines the features applicable to the S6c interface for the feature list with a Feature-List-ID of 1.