7 Scenarios relating to a level of service of session establishment and control of communication session

24.5233GPPArchitecture and functional descriptionCore and enterprise Next Generation Network (NGN) interaction scenariosRelease 17TS

7.1 Scenario 3: Session level virtual leased line

7.1.1 Introduction

This scenario describes the provision of capabilities of the NGN to support an IP multimedia virtual leased service for the NGCN equivalent to a leased-line scenario but between multiple NGCN sites of a single NGCN. This scenario involves primarily the routeing capabilities of the IM CN subsystem within the NGN. The NGCN interfaces to the NGN using SIP as the control protocol. The same NGCN exists at both the originating side and at the terminating side.
Break-in and break-out traffic is not applicable with this scenario.

As this scenario is equivalent to the leased line scenario, the routeing is fixed, i.e. a request at a specific entry point will always be directed to the same exit point of an NGN, the exit point maybe on the boundary between an originating and a terminating NGN hosting session level business communication capabilities or between a terminating NGN and a connected NGCN site. Scenario 6 provides a similar architecture where intelligent capabilities are supported.

7.1.2 Involved functional entities – originating

NOTE: One or more routeing functions can appear in the originating side for this scenario.

Figure 7.1.1: Session level virtual leased line scenario originating functional entities

In this particular scenario the IBCF will route based on information about the entry point, not based on the destination of a request.

7.1.3 Involved functional entities – terminating

NOTE: One or more routeing functions can appear in the terminating side for this scenario.

Figure 7.1.2: Session level virtual leased line scenario terminating functional entities

In this scenario the exit point determined by the originating virtual leased line scenario is the IBCF connecting an NGCN site.

7.1.4 Interoperability with other scenarios

The originating side session level virtual leased line scenario can interoperate with any other terminating scenario where the traffic relates to dialogs or transactions belonging within the enterprise network, e.g. the scenarios for hosted enterprise services.

The terminating side session level virtual leased line scenario can interoperate with any other originating scenario where the traffic relates to dialogs or transactions belonging within the enterprise network, e.g. the scenarios for hosted enterprise services.

NOTE: The functionality provided by the routeing function is that of a SIP proxy, and the functionality provided by the IBCF is that of a session border controller, so interoperability can be provided with existing solutions not based on IMS. In this case, the procedures of 3GPP TS 29.162 [6] will apply at the interworking point. The possible functionalities of a session border controller are described in IETF RFC 5863 [9]. Such interworking may be limited by the SIP extensions that are supported across the interface. ETSI ES 282 001 [3] provides for an IWF which may also provide some appropriate functionality in this respect.

7.1.5 Emergency calls

There is no direct support NGN emergency calls within this scenario, although NGCN emergency calls may be supported. Another scenario has to be used by the enterprise network provider to support NGN emergency calls to or from the enterprise network.

7.1.6 Configuration / provisioning issues

The IBCF need to be configured to route requests coming in over a specific entry point to a specific exit point.

7.1.7 Security issues

3GPP TS 33.210 [10] shall apply to the interconnection between the NGCN and the NGN.

7.1.8 Charging issues

Inter Operator Identifiers (IOI) shall be exchanged between the NGCN and the NGN.

NOTE: IOI usage is not fully defined for enterprise communication in this release.

7.1.9 Transport control issues

NOTE: Definition of the transport control issues in this scenario is outside the scope of this release of the present document.