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4.4.1.4.2 Data specification
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It is possible to specify protocol information elements using class diagrams in a similar way to that shown in Figure 11 and Figure 12 for physical characteristics. However, the UML's lack of encoding rules makes this approach less attractive than the use of ASN.1 in specifying protocol data elements which can be sent, received and understood by a range of implementations from different manufacturers. ETSI ETSI TR 102 105 V1.1.1 (1999-08) 22
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4.4.2 Test specification
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When testing the implementation of a specification, a number of tests on different layers have to be performed. On the bottom layer, conformance to physical specifications is tested; on the top layers, there are interoperability and network integration tests. ETSI has accepted some test suites for these layers as standards (e.g. ETS 300 012-4 [21] ), but they are not usually developed within ETSI. For the middle layers, protocol tests are specified and this is where ETSI actively produces conformance test suites. Thus, within the remainder of this section, the consideration of UML is limited to its use and possible benefits in the specification of protocol tests. ISO/IEC 9646-3 [7] defines a test notation, the Tree and Tabular Combined Notation (TTCN) within the Conformance Testing Methodology and Framework (CTMF). A test suite consists of a number of test cases which are collected into test groups according to common characteristics (e.g., valid / invalid behaviour test). Test cases usually comprise a number of test steps and a test body. Unexpected behaviour is handled by at least one default test step. The essential part of every test case and test step is its behaviour description. TTCN defines basic test events for sending and receiving signals. Timers are managed with special operations to start, check and cancel timers. The corresponding timeout is also a test event. Distributed testing is supported through the concurrent TTCN extension. A test system can consist of a number of test components. The connections between test components and from test components to the System Under Test (SUT) are described with test component configurations. Other specifications included in a test suite are, for example, type and constraints declarations, or Protocol Implementation eXtra Information for Testing (PIXIT) statements.
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4.4.2.1 Feasibility of using the UML for test specification
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With the CTMF and various additional ETSI guidelines, an extensive and proven methodology exists for writing TTCN test specifications. At the moment, there is no need to change this methodology to one that incorporates the UML. The main technical reason for this is that the UML currently lacks many features needed for testing, most notably, timer support. Nevertheless, the UML may be considered for use within the test specification process in two regards: 1) to give a visual representation of certain test suite aspects, thereby increasing the test specification readability; 2) to derive test purposes from a UML protocol specification.
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4.4.2.1.1 Using the UML to increase test specification readability
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ETSI test purpose specifications are usually given as textual descriptions in tables which contain the following rows: - name; - reference; - purpose; - description; - pass criteria; - selection; - preamble; - postamble. Sometimes, informal MSCs are used to provide high level test behaviour descriptions in a graphical form. Detailed MSCs which are used for automatic test generation may be provided as an annex to the test purpose specification document. ETSI ETSI TR 102 105 V1.1.1 (1999-08) 23 Below is a list of the possible uses of the UML to complement the textual descriptions of test purposes. The main goal of using the UML should be to simplify the understanding of the relations between test cases and test steps (preambles and postambles) by providing a graphical view of these relations. - Test purposes can be modelled as class declarations. The text which is included in the test purpose tables can be put in additional named compartments. - Preambles and postambles can be attached to a test purpose declaration through a dependency relationship. - Test grouping can be modelled using a hierarchy of packages. - Test component configurations for concurrent TTCN can be specified in deployment diagrams. Another possibility would be to use UML sequence diagrams instead of MSCs for the test behaviour description. At the moment, this is not feasible as current tools for automatic test generation depend on an MSC test behaviour description. Furthermore, sequence diagrams are not (yet) feature compatible with MSCs.
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4.4.2.1.2 Deriving test purposes from a UML protocol specification
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From a high-level, modelling point of view, test cases seem to be equivalent to UML use cases. Use cases represent the required interactions between a system and actors which are outside the system itself. It is very probable that during testing, an implementation will be checked to ensure that it meets all of the requirements. Therefore, if use cases are defined during the requirements analysis phase of the protocol specification then these use cases may be used as a starting point for test purpose specification. In a later protocol specification stage, processes might be specified as classes with methods corresponding to signals sent to a process. The list of methods, again, may be the basis for test purpose identification.
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4.4.3 Specification of physical characteristics
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4.4.3.1 Standards specifying physical characteristics
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Although specifications related to protocols make up the largest part of ETSI's output of standards, there are also many which specify requirements for the physical characteristics of an item claiming conformance to the standard. Such characteristics include power consumption, electromagnetic radiation, safe access to dangerous voltages and a range of transmission parameters.
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4.4.3.2 Open Network Provision (ONP) leased lines
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4.4.3.2.1 ONP standards
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To assess the feasibility and possible benefits of using object orientation in the development of this type of standard, the range of specifications defining the connection characteristics of the digital Open Network Provision (ONP) leased lines was considered. These standards are: - ETS 300 247 [1] 2 048 kbit/s digital unstructured leased lines (D2048U); - ETS 300 289 [2] 64 kbit/s digital unrestricted leased line with octet integrity (D64U); - ETS 300 419 [3] 2 048 kbit/s digital structured leased lines (D2048S); - ETS 300 687 [4] 34 Mbit/s digital leased lines (D34U and D34S); - ETS 300 688 [5] 140 Mbit/s digital leased lines (D140U and D140S). There is no behaviour specified in any of these standards so there is little benefit in trying to derive sequence diagrams, collaboration diagrams and statecharts. However, since the same set of parameters need to be specified for each leased line type, it is possible to consider class and object diagrams. ETSI ETSI TR 102 105 V1.1.1 (1999-08) 24
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4.4.3.2.2 Traditional specification of leased line characteristics
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These standards already use a loose form of object-orientation by specifying the characterizing parameters of each leased line type in a table of standard entries as shown in Table 3. Table 3: Table of empty connection attributes Connection type attributes Value Description Nature Reference subclause Information transfer rate Information transfer susceptance Structure Establishment of communication Symmetry Communication configuration Network performance sub-attributes Connection type attributes Value Description Nature Reference subclause Transmission delay Jitter Octet slip Error parameters Time interval with errored blocks Value Description Nature Reference subclause Errored seconds Severely errored It can be considered that this table describes in simple terms an ONP Leased Line "class" and that the individual standards instantiate the class by giving values to the attributes to create particular leased line "objects". Table 4 shows how the table is completed in ETS 300 289 [2] to characterize the 64 kbit/s unrestricted leased line with octet integrity (D64U). Table 4: Completed table of connection attributes for 64 kbit/s unrestricted leased line Connection type attributes Value Description Nature Reference subclause Information transfer rate 64 kbit/s See 5.1.1 Information transfer susceptance Unrestricted digital See 5.1.2 Structure Octet integrity See 5.1.3 Establishment of communication Without user intervention See 5.1.4 Symmetry Symmetrical in both directions See 5.1.5 Communication configuration Point-to-point See 5.1.6 Network performance sub-attributes Connection type attributes Value Description Nature Reference subclause Transmission delay Terrestrial and satellite options See 5.1.7.1 Jitter Input and output ports See 5.1.7.2 Octet slip 5 per 24 hour period See 5.1.7.3 Error parameters Time interval with errored blocks Value Description Nature Reference subclause Errored seconds 5 324 per 24 hour period See 5.1.7.4.1 Severely errored seconds 105 per 24 hour period See 5.1.7.4.2
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4.4.3.2.3 Use of UML to specify leased line characteristics
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There are a number of ways in which this information might have been shown using UML rather than tables and Figure 11 indicates one such method. The 'Leased Line' class is shown as an aggregation of the 'Connection Type', 'Network Performance Sub-Attributes' and 'Error Parameters' classes each of which posses attributes which relate exactly to those in the three sections of the table. ETSI ETSI TR 102 105 V1.1.1 (1999-08) 25 Connection Type Information Transfer Rate : Rate Type Information Transfer Susceptance : Susceptance Type Structure : Structure Type Establishment of Communication : Establishment Type Symmetry : Symmetry Type Communication Configuration : Configuration Type Network Performance Sub-Attributes Transmission Delay : DelayType Jitter : JitterType Slip : SlipType Error Parameters Errored Seconds per 24hr : Integer Severely Errored Seconds per 24hr : Integer Leased Line Figure 11: UML specification of an ONP Leased Line Class On its own, this diagram does not add any additional information to that shown in Table 3 but by qualifying each of the attributes with a type, it is possible to use a further class diagram to constrain the attributes to a range of specific values. As can be seen in Figure 12, each of the types has been specified as a <<parameter type>> stereotype which is the aggregation of one of a range <<permitted value>> stereotypes. For example, any attribute of parameter type 'Structure Type' can have the value "Frame Integrity", "Octet Integrity" or "Unstructured" and no other. ETSI ETSI TR 102 105 V1.1.1 (1999-08) 26 Octet Integrity <<permitted value>> Frame Integrity <<permitted value>> Unstructured <<permitted value>> Structure Type <<parameter type>> Symmetrical In Both Directions <<permitted value>> Symmetry Type 139 264 kbit/s <<permitted value>> 139 240 kbit/s <<permitted value>> 2 048 kbit/s <<permitted value>> 1 984 kbit/s <<permitted value>> 64 kbit/s <<permitted value>> Rate Type {xor} {xor} Point-to-Point <<permitted value>> Configuration Type <<parameter type>> With User Intervention <<permitted value>> Without User Intervention <<permitted value>> Establishment Type {xor} <<parameter type>> Unrestricted Digital <<permitted value>> Susceptance Type <<parameter type>> <<parameter type>> <<parameter type>> Figure 12: UML Specification of value ranges for Connection Type attributes Having specified a general class of ONP Leased Line, it is then straightforward to create an instance of this class for each specific leased line type. Figure 13 shows an example of how a definition of the D64U leased line can be expressed as an instance of the Leased Line class. ETSI ETSI TR 102 105 V1.1.1 (1999-08) 27 :Network Performance Sub-Attributes Transmission Delay : Terrestial and satellite Jitter : Input and output ports Slip : 5 per 24 hour period :Connection Type Information Transfer Rate :64 kbit/s Information Transfer Susceptance : Unrestricted digital Structure : Octet integrity Establishment of Communication : Without user intervention Symmetry : Symmetrical in both directions Communication Configuration : Point-to-Point D64U: Leased Line Errored Seconds per 24hr :5324 Severely Errored Seconds per 24hr : 105 :Error Parameters Figure 13: Object instance of D64U Leased Line
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4.4.3.2.4 Summary
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Without developing this model further, it is clear that the UML could be of some value in the early stages of developing standards of this type specifying physical characteristics. However, it is also arguable that the tabular presentation used in the ONP Leased Line standards is adequate for their intended use and that a more complex presentation method might require unnecessary explanation of its syntax and semantics to enable the readers to benefit fully from it.
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4.5 Tool support
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In the standard making process at ETSI, a number of requirements for using new methods (such as the UML) and tools should be met. They are: - the ability to interface to existing methods & standards (MSC, SDL, TTCN, ASN.1) already in use; - the availability of tool support and a common exchange format; - graphical analysis and design notations.
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4.5.1 Current situation
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4.5.1.1 OO notations for industry
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Current trends in specification techniques show that industry needs methods and tools for the following reasons: ETSI ETSI TR 102 105 V1.1.1 (1999-08) 28 - to automate the production of software; - to improve its quality; - to manage system complexity; - to model the system at a high-level independently of any implementation. Before UML emerged, there were several OO modelling languages having many concepts and various different interpretations. The inherent incompatibility of these languages was the main criticism from users wanting to adopt an OO modelling approach. They wanted a modelling language whose foundations are managed by both users and tool vendors in order to guarantee an agreed general purpose OO formalism. On the tool vendor’s side, the main requirement was to have a unique language semantics which fully supports an OO modelling notation. This would allow them to provide tools for model animation and verification. In addition, the impossibility of having a unique format for the exchange of OO models was seen as a restriction in the development of tool support. Obviously, there is a substantial cost induced by using and supporting various modelling environments. All these many reasons have led to a widespread consensus for UML as the convergent OO technology.
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4.5.1.2 Standardization and industrialization of UML
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UML unifies different modelling languages by suppressing many of the differences and redundancies. OMG's specification documents and technical papers are being elaborated continuously to provide a primary source for experts as well as for developers of supporting tools, e.g. modelling tools. OMG support is a fundamental factor in the survival and success of UML as the industry standard object modelling language. It guarantees that, unlike the Booch or OMT languages in the past, UML will not evolve simply by following fashion or current market trends. OMG's process is rigorous, working through from RFP to Recommendation, Amendment and Adoption Vote. Although it does not prevent the making of mistakes or the influence of lobbying groups, it ensures some kind of positive inertia that is of overall benefit to the evolution of the language.
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4.5.1.3 Tool support for UML
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4.5.1.3.1 UML-based tools
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4.5.1.3.1.1 Support for standard UML
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One of the most widely-used UML tools on the market today is Rational Rose from the Rational Software Corporation. Rose supports IS development using the UML notation for the specification and description of systems. It implements a large subset of the UML concepts including UML interfaces and diagrams, propagation of changes from one view to another, provision of capabilities for reverse engineering, and good document generation with links to requirements. Other existing tools which offer similar capabilities to Rational Rose are as follows: - SelectEnterprise from Select Software; - Paradigm Plus from Platinum Technologies; - Software through Pictures from Aonix; - Prosa/om from Prosa Software.
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4.5.1.3.1.2 Support for extended UML
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The current UML notation is missing several of the concepts necessary for the high-level design of real-time systems. The Real-Time Object-Oriented Modelling language (ROOM) which is similar to the UML, offers an alternative to these limitations. However, in Rational's ObjectTime tool which supports ROOM, actions are interpreted in the statechart diagrams and missing concepts such as time constraints are added by proprietary means. These notions have yet to become part of UML and adopted by the OMG. Other existing UML-based tools that support proprietary extensions for real-time characteristics are: ETSI ETSI TR 102 105 V1.1.1 (1999-08) 29 - ARTiSAN from Artisan Software; - COOL:Jex from Sterling Software; - Rhapsody from I-Logix. As with any proprietary extension to a standardized language, there is always a risk that these solutions may not be compatible with the extensions that are ultimately adopted for the UML standard.
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4.5.1.3.2 SDL-UML based tools
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4.5.1.3.2.1 Telelogic Tau
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Telelogic includes support for some UML diagrams in its Tau tool set. Specifically, class diagrams and statechart diagrams can be drawn with the Tau graphical editor. The tool set also provides means for forward engineering from UML to SDL: Classes can be translated into different kinds of type or process definitions. Class attributes are converted to SDL variable declarations, while class operations are translated into procedure references. Statecharts in turn can be converted into SDL process descriptions. Through the support of the UML, Telelogic provides an integrated development environment from requirements analysis through system specification down to target implementation.
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4.5.1.3.2.2 Verilog ObjectGEODE
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Verilog provides extensions, such as a class diagram editor, to its ObjectGEODE tool to support a combined UML-SDL design path. Within the tool, UML is used for high-level modelling and SDL is then used for detailed design and simulation. In a complementary approach, Verilog has developed a direct interface to the Rose tool called ObjectGEODE RoseLink. Developers are able to import into the SDL environment UML analysis models realized with Rose. Object class names, instances and their attributes are then accessible from within the ObjectGEODE internal dictionary and can be used to complete the detailed design with SDL.
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4.5.1.3.3 Tool summary
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To summarize, it can be said that reasonable tool support exists for the UML, although a common interchange format has yet to be implemented. The forward engineering capabilities of existing tools, such as mapping between UML and SDL, are limited. This aspect should be greatly improved when more precise semantics are defined for the UML notation. The incomplete action semantics of UML makes it difficult for an automatic tool to support animation and interpretation of models for the purpose of verification and prototyping.
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4.5.2 What is needed
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4.5.2.1 UML features for strong tool support
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From a tool support point of view, a suitable UML notation should: - allow users to exchange meaningful visual models the tools should support a common interchange format; - provide for new integration between tools, processes and domains in particular the tools should support the extensibility mechanisms (e.g. tags and stereotypes) so that the user can enhance the notation; - stay independent of any programming language or development process the tools should be able to generate different kinds of implementation from an UML model; - provide a formal semantics to simplify the understanding and implementing the modelling language the tools should be able to provide consistent support for checking, simulation and verification; - extend the use of OO modelling to a wide application area ETSI ETSI TR 102 105 V1.1.1 (1999-08) 30 tool support for the extensibility mechanisms should allow the specialization of concepts and constraints for particular application domains; - be adopted by many users as a result of the OMG standard definition tool vendors should address a large and stable market;
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4.5.2.2 Standardization framework for UML
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As part of its mission, the OMG defines new standards for software engineering that allow the modelling of the real world through the representation of objects. Thus, initial design functionality can easily be expanded by, for example, extending some components or adding new objects to the system. This object engineering approach promoted by OMG offers faster application development and improved maintainability as well as producing reusable software. In order to achieve these targets, the OMG is developing the necessary standard specifications, in particular: - UML [12] to facilitate the understanding of complex models and interoperability between various CASE tools, - MOF [13] to define a standard repository metamodel (used to represent the UML metamodel), - XMI [14] to facilitate the exchange of information e.g. UML models between various CASE tools, - CORBA [15] to support distributed object environments ensuring interoperability between different SW and/or HW platforms.
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4.5.2.3 Action semantics for UML
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The provision of an action semantics for UML is the subject of a current RFP aimed at extending UML by the definition of consistent action semantics for statechart transitions and method bodies in the objects. For the UML tool providers, this will allow them to develop verification tools such as simulators to validate the specification. Code generators and other tools are also likely to benefit from the definition of precise semantics. For the UML specifiers, the action semantics will guarantee that they are making models which are: - interoperable; - can be exchanged between different UML tools; - have a behaviour that will be interpreted the same way by every simulator. However it will be noted that, at a first stage, the action semantics are only likely to be optional for UML models so that a tool vendor may not support the action semantics but will still be compliant with UML. Formally defining the meaning of the actions and operations used in UML models will provide for a unique interpretation of the behaviour of the model by all the supporting tools, thus facilitating their interoperability.
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4.5.2.4 XMI interchange format for UML
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XML Metadata Interchange (XMI) is a proposal to an OMG RFP on Stream-based Model Interchange Format (SMIF). The purpose of SMIF is to allow the interchange of models and thus the interchange of information between UML modelling tools and/or metadata repositories based on the OMG MOF standard. It should be stressed that XMI is a transfer format, i.e., any data repository or tool that can encode and decode XMI streams can exchange metadata with other repositories or tools with the same capability. XMI will allow developers of distributed systems to exchange object models and other metadata in the form of streams or files with a standard format based on XML (the eXtensible Markup Language, a W3C standard for the Internet).
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4.5.2.5 Tool interoperability and model extensibility
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A combination of tools from different vendors is often necessary to design a system and to document the developed models and programs. However, in practice, such combinations are difficult to achieve because of poor interchange capabilities which require translation or manual re-entry of information, with the inherent risk of loss and error. XMI tackles the problem of tool interoperability by providing a flexible and parsable information interchange format. Thus, a ETSI ETSI TR 102 105 V1.1.1 (1999-08) 31 tool needs only to be able to save and load the data it uses in XMI format in order to interoperate with other XMI capable tools. The extent of information that can be exchanged between two tools is limited by how much of the information can be understood by both tools. If both share the same metamodel, all of the information transferred can be understood and used. In practice, it is likely that only a subset of the metamodel may be shared, with each tool adding its own extensions. Moreover, having a shared model is not enough on its own. Each tool vendor needs to be able to extend the information content of the model to include pieces of information that have not been included in the shared model. XMI allows a vendor to attach additional information to shared definitions in a way that allows the information to be preserved and passed through a tool that does not understand the information. Using the extension mechanism, an XMI stream can be passed from tool to tool without any information loss.
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4.5.2.6 SDL-UML alignment and tool support
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In respect of ETSI's needs in the standard making process, the mission of a tool manufacturer is to provide its customers with integrated solutions and tools that enhance their productivity, reduce time-to-market and improve the quality of their software. The basic principles of the UML definition meet these needs. Reliance on standards is a key part of such a strategy as can be seen from the tool support for SDL, MSC, TTCN or OMT. Moreover, in this context, UML is an emerging standard that provides a smooth evolution of OMT. Thus the UML technology has become a strategic direction for vendors of tools dedicated to the development of distributed intensive software systems. To enable industrial customers to preserve their investments made with other notations such as OMT, MSC, SDL and TTCN, the tool vendors will support a smooth migration from these notations to the UML solution. It is essential that they work together in order to converge on compatible semantics as far as possible.
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5 Conclusions
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It was not obvious from the summary in Table 1 how and where object orientation would fit into the overall ETSI standards-making process. However, by studying the potential use of the UML in the three most significant types of standard (protocol specifications, the definition of physical characteristics and the specification of test suites) it is clear that object-orientation based on this language could be used within the ETSI standards-making process. Use of the UML should, in many cases, provide additional benefits to those achieved with the methods currently in use. The greatest benefits of using the UML are likely to be realized at the earlier stages of standards development as the language excels in the formalization and expression of requirements but currently lacks the precision and maturity of other notations such as SDL, ASN.1 and TTCN. Although object-oriented methods (mainly GDMO) have traditionally been used in the specification of telecommunications network management services, they have rarely been used in other areas of standardization. To make the best use of the UML across the full spectrum of ETSI's activities, there would need to be a significant change in the general methodology of standards-making such that the overall process becomes "requirements-based" rather than "results-based". In the first instance, the UML could be used as a background tool without any of its constituent diagrams ever appearing in published standards. Such use of the UML within this methodology would, in itself, yield considerable benefits. Support of the UML in automatic tools is growing fast and, most importantly, is already available in the established SDL tools although they do not offer the full range of UML diagrams. Other tools dedicated solely to the UML are available but few of these support the complete graphical set. However, the tools are likely to grow with the language such that a lack of tool capability is unlikely to hamper the use of the UML by ETSI. With a formal graphical language such as the UML, it is essential that a simple set of guidelines is available to standards writers in order to realize the full range of benefits that are available through the intelligent and consistent use of the language. ETSI ETSI TR 102 105 V1.1.1 (1999-08) 32 Annex A (informative): Useful WWW addresses The following URLs can be accessed for further information on UML publications and tools: The Object Management Group http://www.omg.org Verilog http://www.verilogusa.com Telelogic http://www.telelogic.se Rational Software Corporation http://www.rational.com Select Software http://www.selectst.com Platinum Technologies http://www.platinum.com Aonix Software http://www.aonix.com Prosa Software http://www.prosa.fi Artisan Software http://www.artisansw.com Sterling Software http://www.sterling.com I-Logix http://www.ilogix.com ETSI ETSI TR 102 105 V1.1.1 (1999-08) 33 Bibliography The following material, though not specifically referenced in the body of the present document (or not publicly available), gives supporting information. - ITU-T Recommendation Z.109: "SDL in combination with UML". - Schneider & Winters: "Applying Use Cases", Addison-Wesley (1998), ISBN 0-201-3-981-5. - Jacobsen, Booch & Rumbaugh: "The Unified Software Development Process", Addison-Wesley (1999), ISBN 0-201-57169-2. ETSI ETSI TR 102 105 V1.1.1 (1999-08) 34 History Document history V1.1.1 August 1999 Publication ISBN 2-7437-3267-9 Dépôt légal : Août 1999
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1 Scope
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The present document specifies interoperability Test Descriptions (TDs) for Inter-IMS Network to Network Interface (II-NNI) interoperability testing for the IP Multimedia Call Control Protocol based on Stage 3 Session Initiation Protocol (SIP) and Session Description Protocol (SDP) standard, TS 124 229 [1]. Interconnection aspects between two different IM CN subsystems for end to end service interoperability are based on standard TS 129 165 [16]. TDs have been specified on the basis of the Test Purposes (TPs) and Test Suite Structure (TSS) presented in TS 186 011-1 [2]. TP fragments presented in the present document as part of TDs are defined using the TPLan notation of ES 202 553 [5]. TDs have been written based on the test specification framework described in TS 102 351 [3] and the interoperability testing methodology defined in TS 102 237-1 [4], i.e. interoperability testing with a conformance relation. For the assessment of IMS core network requirements related to the ISC interface parts of the supplementary services HOLD (see TS 124 410 [10]), CDIV (see TS 124 404 [11]), ACR-CB (see TS 124 411 [12]), and OIP/OIR (see TS 124 407 [13]) have been used. The scope of these test descriptions is not to cover all requirements specified in TS 124 229 [1]. TDs have been only specified for requirements that are observable at the interface between two IMS core network implementations, i.e. IMS NNI. NOTE: Requirements pertaining to a UE or an AS implementation or IMS core network requirements that can only be observed at the interface between UE and IMS CN are explicitly not within the scope of the present document. The latter requirements have been dealt with from a UE and conformance perspective in TS 134 229-1 [6].
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186 011-2
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2 References
|
References are either specific (identified by date of publication and/or edition number or version number) or non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the reference document (including any amendments) applies. Referenced documents which are not found to be publicly available in the expected location might be found at http://docbox.etsi.org/Reference. NOTE: While any hyperlinks included in this clause were valid at the time of publication ETSI cannot guarantee their long term validity.
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1b570a6648bd6e802a749e39655a3b23
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186 011-2
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2.1 Normative references
|
The following referenced documents are necessary for the application of the present document. [1] ETSI TS 124 229 (V9.5.0): "Digital cellular telecommunications system (Phase 2+); Universal Mobile Telecommunications System (UMTS); LTE; IP multimedia call control protocol based on Session Initiation Protocol (SIP) and Session Description Protocol (SDP); Stage 3 (3GPP TS 24.229 version 9.5.0 Release 9)". [2] ETSI TS 186 011-1 (V4.1.3): "IMS Network Testing (INT); IMS NNI Interoperability Test Specifications; Part 1: Test Purposes for IMS NNI Interoperability". [3] ETSI TS 102 351: "Methods for Testing and Specification (MTS); Internet Protocol Testing (IPT); IPv6 Testing: Methodology and Framework". [4] ETSI TS 102 237-1: "Telecommunications and Internet Protocol Harmonization Over Networks (TIPHON) Release 4; Interoperability test methods and approaches; Part 1: Generic approach to interoperability testing". [5] ETSI ES 202 553: "Methods for Testing and Specification (MTS); TPLan: A notation for expressing Test Purposes". ETSI ETSI TS 186 011-2 V4.1.3 (2012-05) 9 [6] ETSI TS 134 229-1: "Universal Mobile Telecommunications System (UMTS); LTE; Internet Protocol (IP) multimedia call control protocol based on Session Initiation Protocol (SIP) and Session Description Protocol (SDP); Part 1: Protocol conformance specification (3GPP TS 34.229- 1 Release 8)". [7] ETSI TS 133 203: "Digital cellular telecommunications system (Phase 2+); Universal Mobile Telecommunications System (UMTS); LTE; 3G security; Access security for IP-based services (3GPP TS 33.203 Release 8)". [8] IETF RFC 2617: "HTTP Authentication: Basic and Digest Access Authentication". [9] IETF RFC 3966: "The tel URI for Telephone Numbers". [10] ETSI TS 124 410: "Digital cellular telecommunications system (Phase 2+); Universal Mobile Telecommunications System (UMTS); TISPAN; NGN Signalling Control Protocol; Communication HOLD (HOLD) PSTN/ISDN simulation services; Protocol specification (3GPP TS 24.410 Release 8)". [11] ETSI TS 124 404: "Digital cellular telecommunications system (Phase 2+); Universal Mobile Telecommunications System (UMTS); TISPAN; PSTN/ISDN simulation services: Communication Diversion (CDIV); Protocol specification (3GPP TS 24.404 Release 7)". [12] ETSI TS 124 411: "Digital cellular telecommunications system (Phase 2+); Universal Mobile Telecommunications System (UMTS); TISPAN; PSTN/ISDN simulation services: Anonymous Communication Rejection (ACR) and Communication Barring (CB); Protocol specification (3GPP TS 24.411 Release 7)". [13] ETSI TS 124 407: "Digital cellular telecommunications system (Phase 2+); Universal Mobile Telecommunications System (UMTS); TISPAN; PSTN/ISDN simulation services; Originating Identification Presentation (OIP) and Originating Identification Restriction (OIR); Protocol specification (3GPP TS 24.407 Release 7)". [14] ETSI TS 183 063: "Telecommunications and Internet converged Services and Protocols for Advanced Networking (TISPAN); IMS-based IPTV stage 3 specification". [15] ETSI TS 124 247: "Digital cellular telecommunications system (Phase 2+); Universal Mobile Telecommunications System (UMTS); LTE; Messaging service using the IP Multimedia (IM) Core Network (CN) subsystem; Stage 3 (3GPP TS 24.247 Release 9)". [16] ETSI TS 129 165: "Digital cellular telecommunications system (Phase 2+); Universal Mobile Telecommunications System (UMTS); LTE; Inter-IMS Network to Network Interface (NNI) (3GPP TS 29.165 version 9.5.0 Release 9)". [17] ETSI TS 102 901: "IMS Network Testing (INT); IMS NNI Interoperability Test Specifications; IMS NNI interoperability test descriptions for RCS". [18] ETSI TS 129 163 (V9.4.0): "Digital cellular telecommunications system (Phase 2+); Universal Mobile Telecommunications System (UMTS); LTE; Interworking between the IP Multimedia (IM) Core Network (CN) subsystem and Circuit Switched (CS) networks (3GPP TS 29.163 version 9.4.0 Release 9)".
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1b570a6648bd6e802a749e39655a3b23
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186 011-2
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2.2 Informative references
|
The following referenced documents are not necessary for the application of the present document but they assist the user with regard to a particular subject area. [i.1] ETSI TR 133 978: "Universal Mobile Telecommunications System (UMTS); Security aspects of early IP Multimedia Subsystem (IMS) (3GPP TR 33.978 version 7.0.0 Release 7)". [i.2] ETSI TR 123 981: "Universal Mobile Telecommunications System (UMTS); LTE; Interworking aspects and migration scenarios for IPv4-based IP Multimedia Subsystem (IMS) implementations (3GPP TR 23.981 Release 8)". ETSI ETSI TS 186 011-2 V4.1.3 (2012-05) 10 [i.3] ETSI TR 184 008: "Telecommunications and Internet converged Services and Protocols for Advanced Networking (TISPAN); Infrastructure ENUM Options for a TISPAN IPX". [i.4] IETF RFC 3761: "The E.164 to Uniform Resource Identifiers (URI); Dynamic Delegation Discovery System (DDDS) Application (ENUM)". [i.5] GSMA PRD IR.67: "DNS/ENUM Guidelines for Service Providers & GRX/IPX Providers" ver.5.1. [i.6] IETF RFC 3403: "Dynamic Delegation Discovery System (DDDS), Part Three: The Domain Name System (DNS) Database".
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186 011-2
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3 Abbreviations
|
For the purposes of the present document, the following abbreviations apply: 3GPP 3rd Generation Partnership Project ACL Automatic Congestion Level ACM Address Complete Message ACR Anonymous Communication Rejection ACR-CB Anonymous Communication Rejection – Communication Barring AKA Authentication and Key Agreement ALG Application Level Gateway ANM Answer Message AS (IMS) Application Server BC Broadcast CB Call Barring CDIV Call DIVersion CF (Test) ConFiguration CFU Call Forward Unconditional CFW Call FloW CN Core Network CoD Content on Demand CPG Call Progress Message CS Circuit Switched CSCF Call Session Control Function DB Enum database DHCP Dynamic Host Configuration Protocol DNS Domain Name System ENUM E.164 Number Mapping GSM Global System for Mobile Communications GSMA GSM Association HOLD Communication HOLD HSS Home Subscriber Server IAM Initial Address Message IAM_A Not applicable IBCF Interconnection Border Control Gateway I-CSCF Interrogating CSCF IFC Initial Filter Criteria II-NNI Not applicable IM IP Multimedia IMS IP Multimedia Subsystem IOI Inter Operator Identifier IP Internet Protocol IPsec Internet Protocol security IPTV IP Television IR Not applicable, document reference ISC IMS Service Control ISDN Integrated Service Digital Network ISUP ISDN User Part IUT Implementation Under Test ETSI ETSI TS 186 011-2 V4.1.3 (2012-05) 11 MF Media Function MGCF Media Gateway Control Function MGF Media Gateway Function MRFC Multimedia Resource Function Controller MRFP Multimedia Resource Function Processor MSRP Message Session Relay Protocol MTP Message Transfer Part NAPTR Naming Authority Pointer NNI Network-to-Network Interface N-PVR Network based Personal Video Recording NS Name Server OCB Outgoing Communication Barring OIP Originating Identification Presentation OIR Originating Identification Restriction PCM Pulse Code Modulation PCO Point of Control and Observation PCRF Policy and Charging Rules Function P-CSCF Proxy CSCF PO Point of Observation PoI Point of Interconnection PRACK Reliability of Provisional Responses PRD Not applicable, document reference PSTN Public Switched Telephone Network PVR Personal video recorder services RLC Release Complete Message RTSP Real Time Streaming Protocol SA Security Association SCF Session Control Function S-CSCF Serving CSCF SCTP Stream Control Transmission Protocol SDF Service Discovery Function SDP Session Description Protocol SGF Signalling Gateway Function SIP Session Initiation Protocol SS Simulation Services SUT System Under Test TCP Transmission Control Protocol TD Test Description TISPAN Telecommunications and Internet converged Services and Protocols for Advanced Networking TN Telephone Number TP Test Purpose TPLan Test Purpose Notation TSS Test Suite Structure TTL Time to live UC Use Case UC_2_I Not applicable UDP User Datagram Protocol UE User Equipment URI Uniform Record Identifier VoIP Voice over Internet Protocol XML eXtensible Markup Language
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186 011-2
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4 IMS NNI Interoperability Test Specification
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1b570a6648bd6e802a749e39655a3b23
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186 011-2
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4.1 Introduction
|
The IMS NNI Interoperability Test Descriptions (TDs) defined in the following clauses are derived from the Test Purposes (TPs) specified in TS 186 011-1 [2]. The TDs cover both basic call procedures such as call establishment and call release and a selection of the most common supplementary services. ETSI ETSI TS 186 011-2 V4.1.3 (2012-05) 12
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1b570a6648bd6e802a749e39655a3b23
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186 011-2
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4.2 Test Prerequisites
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1b570a6648bd6e802a749e39655a3b23
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186 011-2
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4.2.1 IP Version
|
These test specifications are based on the use of IPv4 for SIP message transport throughout all IMS nodes as specified in TR 123 981 [i.2] but do not exclude the use of IPv6 in the case that all involved IMS nodes support this version of the IP protocol.
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1b570a6648bd6e802a749e39655a3b23
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186 011-2
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4.2.2 Authentication and Security
|
The current test specification supports as default full IMS TS 133 203 [7] 3GPP security. Non-compliance with full IMS security features defined in TS 133 203 [7] is expected to be a problem mainly at the UE side, because of the potential lack of support of the USIM/ISIM interface (especially in 2G-only devices) and of the potential inability to support IPsec on some UE platforms. For those reasons, fallback to early IMS TR 133 978 [i.1] and SIP Digest authentication without key agreement and null authentication may be used to achieve satisfactory test results. Tests should however be executed with full IMS security if all required IMS nodes support it.
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1b570a6648bd6e802a749e39655a3b23
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186 011-2
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4.2.3 Registration and Subscription
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1b570a6648bd6e802a749e39655a3b23
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186 011-2
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4.2.3.1 SIP Call Flow
|
This clause describes the registration call flow under the authentication and security scope described in clause 4.2.2.
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1b570a6648bd6e802a749e39655a3b23
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186 011-2
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4.2.3.1.1 Early IMS Registration and Subscription Call Flow
|
Early IMS security does not allow SIP requests to be protected using an IPsec Security Association (SA) because it does not perform a key agreement procedure. IPsec security associations are not set up between UE and P-CSCF, as they are in the full IMS security solution. For early IMS security, the expected registration and subscription sequence is: Step Direction Message Comment UE IMS 1 The UE establishes an IP bearer as required by its specific access network (optional). 2 P-CSCF address discovery using DHCP procedures for IPv4 (optional). 3 REGISTER The UE sends initial registration for IMS services. Unprotected 4 200 OK The IMS responds with 200 OK. 5 SUBSCRIBE The UE subscribes to its registration event package. 6 200 OK or 202 Accepted The IMS responds with 200 OK or 202 Accepted. 7 NOTIFY The IMS sends initial NOTIFY for registration event package, containing full registration state information for the registered public user identity in the XML body. 8 200 OK The UE responds with 200 OK. ETSI ETSI TS 186 011-2 V4.1.3 (2012-05) 13
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1b570a6648bd6e802a749e39655a3b23
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186 011-2
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4.2.3.1.2 Full IMS Registration and Subscription Call Flow
|
For full IMS security, the expected registration and subscription sequence is: Step Direction Message Comment UE IMS 1 The UE establishes an IP bearer as required by its specific access network (optional). 2 P-CSCF address discovery using DHCP procedures for IPv4 (optional). 3 REGISTER The UE sends initial registration for IMS services. Unprotected 4 401 Unauthorized The IMS responds with a valid Digest AKA authentication challenge and a list of integrity and encryption algorithms supported by the network as defined in the IMS_AKA procedure of TS 133 203 [7]. 5 Upon receipt of 401 Unauthorized, the UE selects the first integrity and encryption algorithm combination on the list received from the P-CSCF in 401 Unauthorized which is also supported by the UE. If the P-CSCF did not include any confidentiality algorithm in 401 Unauthorized then the UE shall select the NULL encryption algorithm. The UE then proceeds to establish two new pairs of IPSEC Security Associations (SA1 and SA2). 6 REGISTER The UE sends another REGISTER with authentication credentials over IPSEC security association SA1. Protected by SA1 7 200 OK The IMS responds with 200 OK over the same IPSEC security association SA1. 8 SUBSCRIBE The UE subscribes to its registration event package over the IPSEC security association SA2. Protected by SA2 9 200 OK or 202 Accepted The IMS responds with 200 OK or 202 Accepted over the IPSEC security association SA2. 10 NOTIFY The IMS sends initial NOTIFY for registration event package, containing full registration state information for the registered public user identity in the XML body, over the IPSEC security association SA2. 11 200 OK The UE responds with 200 OK over the IPSEC security association SA2. ETSI ETSI TS 186 011-2 V4.1.3 (2012-05) 14
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1b570a6648bd6e802a749e39655a3b23
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186 011-2
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4.2.3.1.3 SIP Digest Registration and Subscription Call Flow
|
For SIP Digest authentication without key agreement and null authentication, the expected registration and subscription sequence is: Step Direction Message Comment UE IMS 1 The UE establishes an IP bearer as required by its specific access network (optional). 2 P-CSCF address discovery using DHCP procedures for IPv4 (optional). 3 REGISTER The UE sends initial registration for IMS services. Unprotected 4 401 Unauthorized The IMS responds with a valid HTTP Digest authentication challenge as defined in RFC 2617 [8]. 5 REGISTER The UE sends another REGISTER with authentication credentials. 6 200 OK The IMS responds with 200 OK. 7 SUBSCRIBE The UE subscribes to its registration event package. 8 200 OK or 202 Accepted The IMS responds with 200 OK or 202 Accepted. 9 NOTIFY The IMS sends initial NOTIFY for registration event package, containing full registration state information for the registered public user identity in the XML body. 10 200 OK The UE responds with 200 OK.
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1b570a6648bd6e802a749e39655a3b23
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186 011-2
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4.2.4 Supported Options
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1b570a6648bd6e802a749e39655a3b23
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186 011-2
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4.2.4.1 Security
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Support for security agreement is optional in case of Full IMS Reg. It shall only be used in case all IMS nodes support it.
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1b570a6648bd6e802a749e39655a3b23
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186 011-2
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4.2.4.2 Signalling Compression
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"No SigComp" is the default signalling configuration in all test descriptions. Tests may be executed with signalling compression if the required nodes support it.
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1b570a6648bd6e802a749e39655a3b23
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186 011-2
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4.2.5 Number Resolution
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"ENUM (RFC 3761 [i.4]) is a capability that transforms E.164 numbers into domain names and then uses the DNS (Domain Name System) to discover NAPTR records that specify the services available for a specific domain name." (TR 184 008 [i.3]). The test infrastructure focuses on the use of Infrastructure ENUM to map a telephone number into a SIP URI that could identify a specific point of interconnection (PoI) to that communication provider's network that could enable the originating party to establish communication with the associated terminating party either directly or through an IPX. The Infrastructure ENUM platform has a tiered structure and provides authoritative, service specific information to the quering party. A combination of Tier 0, Tier 1 and Tier 2 registries enables global discovery of ENUM data. When returning the SIP URI of an PoI the ENUM solution acts a hosted T2 ENUM registry for the number range holder. When returning a NS record the ENUM solution acts as either a Tier 0 or Tier 1 registry.
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1b570a6648bd6e802a749e39655a3b23
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186 011-2
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4.3 Test Infrastructure
|
In these clauses we define the involvement of the various IMS nodes specifically as they pertain to NNI testing. The configuration of the nodes is described. Points of control and observation are identified and static test configurations are described. The Mw interface or the Ic interface if topology hiding is required is the interface under observation for NNI interoperability testing. ETSI ETSI TS 186 011-2 V4.1.3 (2012-05) 15
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1b570a6648bd6e802a749e39655a3b23
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186 011-2
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4.3.1 Core IMS Nodes
|
The current testing scope includes IMS roaming and border control functionality. For IMS roaming, Mw reference point between IMS core in visited network (P-CSCF) and IMS core in home network will be monitored for testing purposes. For border control functionality, Mx reference point between IMS Core and IBCF, Ici reference point between an IBCF and another IBCF or I-CSCF belonging to a different IM CN subsystem network and Izi reference point between a TrGW and another TrGW or media handling node belonging to a different IM CN subsystem network will be monitored for testing purposes. For all test cases not requiring IMS roaming or border control functionality, P-CSCF, S-CSCF, I-CSCF, IBCF, and HSS are considered to be within a "black box" for testing purposes, i.e. the System Under Test (SUT). Interfaces within the IMS (excluding Mx reference point between IMS Core and IBCF when border control functionality is required) are considered internal and not observable for testing purposes.
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1b570a6648bd6e802a749e39655a3b23
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186 011-2
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4.3.1.1 P-CSCF
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1b570a6648bd6e802a749e39655a3b23
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186 011-2
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4.3.1.1.1 Relevant Interfaces
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The P-CSCF constitutes the point of entry for UE signalling into the IMS core. The Gm interface between the P-CSCF and the UE is used as a point of control and observation (PCO) for NNI interoperability testing purposes. In the case of IMS roaming configurations the Mw reference point of the P-CSCF is exposed at the NNI and used there as a point of observation (PO).
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1b570a6648bd6e802a749e39655a3b23
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186 011-2
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4.3.1.1.2 Node Configuration
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The P-CSCF should be configured to support the pre-requisites outlined in clause 4.2.
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1b570a6648bd6e802a749e39655a3b23
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186 011-2
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4.3.1.2 S-CSCF
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1b570a6648bd6e802a749e39655a3b23
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186 011-2
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4.3.1.2.1 Relevant Interfaces
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The S-CSCF is the core IMS node delivering IMS services to subscribers. When no border control functionalities are applied, the Mw reference point between the S-CSCF and either I- or S-CSCF in another network domain is used as a PO against which NNI interoperability tests are validated. The Mw interfaces between I- and S-CSCFs within the same network are considered to be internal IMS interfaces. Although considered as internal and not explicitly involved in all NNI test configurations, it is recommended that these interface are exposed for troubleshooting purposes. When border control functionalities are applied, the Mx reference point between S-CSCF and IBCF within the same network domain, is used as a PO for NNI interoperability checks.
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1b570a6648bd6e802a749e39655a3b23
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186 011-2
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4.3.1.2.2 Node Configuration
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The S-CSCF should be configured to support the pre-requisites outlined in clause 4.2. When applicable based on the specific configuration, the S-CSCF must be provisioned to support required Application Servers (AS) as trusted nodes.
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1b570a6648bd6e802a749e39655a3b23
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186 011-2
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4.3.1.3 I-CSCF
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1b570a6648bd6e802a749e39655a3b23
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186 011-2
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4.3.1.3.1 Relevant Interfaces
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The I-CSCF is the contact point within an operator's network for all connections destined to a user of that network operator, or a roaming user currently located within that network operator's service area. When no border control functionalities are applied, the Mw reference point between the I-CSCF and an S-CSCF in another network domain is used as a PO against which NNI interoperability tests are validated. The Mw interfaces between I- and S-CSCFs within the same network are considered to be internal IMS interfaces. Although considered as internal and not explicitly involved in all NNI test configurations, it is recommended that these interface are exposed for troubleshooting purposes. When border control functionalities are applied, the Mx reference point between I-CSCF and IBCF within the same network domain, is used as a PO for NNI interoperability checks.
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1b570a6648bd6e802a749e39655a3b23
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186 011-2
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4.3.1.3.2 Node Configuration
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The I-CSCF should be configured to support the pre-requisites outlined in clause 4.2. ETSI ETSI TS 186 011-2 V4.1.3 (2012-05) 16
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1b570a6648bd6e802a749e39655a3b23
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186 011-2
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4.3.1.4 IBCF
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1b570a6648bd6e802a749e39655a3b23
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186 011-2
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4.3.1.4.1 Relevant Interfaces
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The IBCF is the core IMS node providing border control functionalities such as topology hiding, transport plane control, screening of SIP signalling or application level gateway (for instance enabling communication between IPv6 and IPv4 SIP applications). However, the IBCF can act also as a pass-through entity between adjacent IMS networks. The IcI reference point between the IBCF and either IBCF or I- or S-CSCF in another network domain is used as a PO against which NNI interoperability tests are validated.
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1b570a6648bd6e802a749e39655a3b23
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186 011-2
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4.3.1.4.2 Node Configuration
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The IBCF should be configured to support the pre-requisites outlined in clause 4.2. The IBCF node will be present in all tests to be executed. In case the requirement to support topology hiding is not explicitly stated in the pre-conditions of a test description it shall be assumed that the IBCF does not apply this functionality. In case the requirement to support application level gateway (ALG) is not explicitly stated in the pre-conditions of a test description it shall be assumed that the IBCF does not apply this functionality.
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1b570a6648bd6e802a749e39655a3b23
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186 011-2
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4.3.1.5 HSS
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1b570a6648bd6e802a749e39655a3b23
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186 011-2
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4.3.1.5.1 Relevant Interfaces
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The HSS constitutes the repository for IMS subscriber information. The Cx interface between the HSS and the S-CSCF and/or I-CSCF is considered an internal IMS interface.
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1b570a6648bd6e802a749e39655a3b23
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186 011-2
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4.3.1.5.2 Node Configuration
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The HSS should be configured within each IMS participating in an interoperability test, i.e. IMS_A as well as IMS_B, to interact with CSCFs as required using DIAMETER Cx interfaces. Users should be provisioned to match the sample profiles listed in table 1. In addition, each IMS shall have its own unique domain. Also the phone numbers configured in the two IMSes participating in an interoperability test shall be unique, i.e. IMS_A and IMS_B shall have no phone numbers in common. All public identities belong to the same implicitly registered set. Table 1: HSS sample user profiles Private Identity Public Identity 1 (SIP URI) Public Identity 2 (Tel URI) Default Public Identity Filter criteria userGEN_priv userGEN na 1 na userSIP_priv userSIP e.g. tel:+330123402 1 na userTEL_priv userTEL e.g. tel:+330123403 2 na userNOAS_priv userNOAS na 1 contact AS on terminating INVITE SESSION_TERMINATED userHOLD_priv userHOLD na 1 contact HOLD AS userOIP_priv userOIP na 1 contact OIP AS userOIR_priv userOIR na 1 contact OIR AS userACR_priv userACR na 1 contact ACR AS userCFU_priv userCFU na 1 contact CFU AS userIPTV_priv userIPTV na 1 Contact IPTV AS Public user identity may take the form of SIP or TEL URIs (RFC 3966 [9]). EXAMPLE 1: sip: userGEN@ims_a.net. EXAMPLE 2: tel: +330123402. A private user identity may also take the form of- <imsi>@ims.<xxx>mnc.<yyy>.mcc.3gppnetwork.org. EXAMPLE 3: [email protected]. ETSI ETSI TS 186 011-2 V4.1.3 (2012-05) 17
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1b570a6648bd6e802a749e39655a3b23
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186 011-2
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4.3.1.6 MRFC
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1b570a6648bd6e802a749e39655a3b23
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186 011-2
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4.3.1.6.1 Relevant Interfaces
|
The Media Resource Function Controller (MRFC) is a signalling plane node that acts as a SIP User Agent to the S-CSCF, and which controls the MRFP across an H.248 interface. The Mr interface between the MRFC and the S-CSCF, the Cr/Sr interfaces to the AS and the Mp interface to the MRFP are considered internal IMS interfaces.
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1b570a6648bd6e802a749e39655a3b23
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186 011-2
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4.3.1.6.2 Node Configuration
|
The MRFC should be configured to support the pre-requisites outlined in clause 4.2. The need to activate the MRFC as part of an IMS core network depends highly on the test description to be executed.
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1b570a6648bd6e802a749e39655a3b23
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186 011-2
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4.3.1.7 MRFP
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1b570a6648bd6e802a749e39655a3b23
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186 011-2
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4.3.1.7.1 Relevant Interfaces
|
The Media Resource Function Processor (MRFP) is a media plane node that implements all media-related functions. The Mp interface between the MRFP and the MRFC is considered an internal IMS interface.
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1b570a6648bd6e802a749e39655a3b23
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186 011-2
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4.3.1.7.2 Node Configuration
|
The MRFP should be configured to support the pre-requisites outlined in clause 4.2. The need to activate the MRFP as part of an IMS core network depends highly on the test description to be executed.
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1b570a6648bd6e802a749e39655a3b23
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186 011-2
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4.3.1.8 MGCF
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1b570a6648bd6e802a749e39655a3b23
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186 011-2
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4.3.1.8.1 Relevant Interfaces
|
The Media Gateway Controller Function (MGCF) does call control protocol conversion between SIP and ISUP. It also controls the resources in a Media Gateway across an H.248 interface. The Mg reference point between the MGCF and an I-CSCF in the same network domain is used as a PO against which NNI interoperability tests are validated. The E1 reference point to the CS network is used to verify the codings of the ISUP messages.
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1b570a6648bd6e802a749e39655a3b23
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186 011-2
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4.3.1.8.2 Node Configuration
|
The MGCF should be configured to support the pre-requisites outlined in clause 4.2. The need to activate the MGCF as part of an IMS core network depends highly on the test description to be executed.
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1b570a6648bd6e802a749e39655a3b23
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186 011-2
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4.3.1.9 MGF
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1b570a6648bd6e802a749e39655a3b23
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186 011-2
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4.3.1.9.1 Relevant Interfaces
|
The Media Gateway Function (MGF) interfaces with the media plane of the CS network, by converting between RTP and PCM. It can also transcode when the codecs do not match. The reference points of the MGF with other entities are out of the scope of the test descriptions in the present document.
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1b570a6648bd6e802a749e39655a3b23
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186 011-2
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4.3.1.9.2 Node Configuration
|
The MGF should be configured to support the pre-requisites outlined in clause 4.2. The need to activate the MGF as part of an IMS core network depends highly on the test description to be executed. ETSI ETSI TS 186 011-2 V4.1.3 (2012-05) 18
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1b570a6648bd6e802a749e39655a3b23
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186 011-2
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4.3.1.10 SGF
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1b570a6648bd6e802a749e39655a3b23
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186 011-2
|
4.3.1.10.1 Relevant Interfaces
|
The Signalling Gateway Function (SGF) interfaces with the signalling plane of the CS. It transforms lower layer protocols as Stream Control Transmission Protocol (SCTP) into Message Transfer Part (MTP) protocol), to pass ISDN User Part (ISUP) from the MGCF to the CS network.
|
1b570a6648bd6e802a749e39655a3b23
|
186 011-2
|
4.3.1.10.2 Node Configuration
|
The SGF should be configured to support the pre-requisites outlined in clause 4.2. The need to activate the SGF as part of an IMS core network depends highly on the test description to be executed.
|
1b570a6648bd6e802a749e39655a3b23
|
186 011-2
|
4.3.2 External IMS core Nodes
| |
1b570a6648bd6e802a749e39655a3b23
|
186 011-2
|
4.3.2.1 UE
| |
1b570a6648bd6e802a749e39655a3b23
|
186 011-2
|
4.3.2.1.1 Relevant Interfaces
|
The UE is considered to act as a stimulus node in this test specification. The Gm interface between the P-CSCF and the UE is used as a Point of Control and Observation (PCO) for NNI interoperability tests.
|
1b570a6648bd6e802a749e39655a3b23
|
186 011-2
|
4.3.2.1.2 Node Configuration
|
The UE should be configured to support the pre-requisites outlined in clause 4.2. The test descriptions in the present document assume that a UE supports basic call and messaging functionality, target refresh based on UPDATE and on re-INVITE method, message transport via UDP and TCP, and the use of at least one of the supplementary services HOLD (see TS 124 410 [10]), CDIV (see TS 124 404 [11]), ACR-CB (see TS 124 411 [12]) or OIP/OIR (see TS 124 407 [13]). In the case that a UE does not meet one or more of these features, only a selected subset of the test descriptions in the present document should be used for IMS core network interoperability testing, i.e. test descriptions which do not contain any pass criteria related to these features.
|
1b570a6648bd6e802a749e39655a3b23
|
186 011-2
|
4.3.2.2 AS
| |
1b570a6648bd6e802a749e39655a3b23
|
186 011-2
|
4.3.2.2.1 Relevant Interfaces
|
Interworking between external Application Servers (AS) and the IMS core is under the scope of the present document. The ISC interface between the S-CSCF and the AS is used as a Point of Observation (PO) for NNI interoperability tests.
|
1b570a6648bd6e802a749e39655a3b23
|
186 011-2
|
4.3.2.2.2 Node Configuration
|
The AS should be configured to support the pre-requisites outlined in clause 4.2. The test descriptions in the present document assume that an AS supports the use of the supplementary services HOLD (see TS 124 410 [10]), CDIV (see TS 124 404 [11]), ACR-CB (see TS 124 411 [12]), OIP/OIR (see TS 124 407 [13]), IPTV(see TS 183 063 [14]) or Conference (see TS 124 247 [15]). In the case that an AS does not support one or more of these supplementary services, only a selected subset of the test descriptions in the present document should be used for IMS core network interoperability testing, i.e. test descriptions which do not contain any pass criteria related to these supplementary services. ETSI ETSI TS 186 011-2 V4.1.3 (2012-05) 19
|
1b570a6648bd6e802a749e39655a3b23
|
186 011-2
|
4.3.3 Supporting IMS Nodes
| |
1b570a6648bd6e802a749e39655a3b23
|
186 011-2
|
4.3.3.1 DNS
| |
1b570a6648bd6e802a749e39655a3b23
|
186 011-2
|
4.3.3.1.1 Relevant Interfaces
|
The Domain Name Service (DNS) is considered as a supporting entity in this test specification. It is assumed that each IMS has its own local DNS which is connected to the common interconnect DNS.
|
1b570a6648bd6e802a749e39655a3b23
|
186 011-2
|
4.3.3.1.2 Node Configuration
|
The common DNS should be configured for appropriate resource record handling as required to support proper resolution of all SIP URIs in Request URIs and Route headers.
|
1b570a6648bd6e802a749e39655a3b23
|
186 011-2
|
4.3.3.2 ENUM
|
When testing a combination of local and external registries can be used to simulate all functions of the Tier 0, Tier 1 and Tier 2 registries operation plus all national and international interconnect scenarios. It is assumed that each IMS core may access a local ENUM solution and an external ENUM solution with query capabilities or a combination of local and external solutions to allow retrieval of ENUM data.
|
1b570a6648bd6e802a749e39655a3b23
|
186 011-2
|
4.3.3.2.1 Local ENUM Solution
|
Each IMS may access a local ENUM solution with query capabilities which allows retrieval of authoritative stored ENUM data (usually Tier 2 data) or authoritative cached ENUM data (any Tier).
|
1b570a6648bd6e802a749e39655a3b23
|
186 011-2
|
4.3.3.2.2 Common ENUM Solution
|
An external ENUM registry is provided by the GSMA PRD IR.67 [i.5] to simulate a Tier 0 global root, national Tier 1 registries and off board Tier 2 registries. Depending on the scenario in simulation the registry allows to resolve a TN either directly with the SIP URI of the appropriate interconnection point or indirectly with a NS record of the destination operator. The NS record can then be used by the local ENUM solution to obtain a SIP URI. The test participants select the required features in order to implement particular simulation scenarios. For the test participants the registry offers: • an interface to manage user accounts; • a provisioning interface for entering relevant information (E.164 number, SIP URI or NS record etc.) into the database; and • a query interface accepting NAPTR queries and responding with NAPTR responses. As an example, the ENUM service should have an entry to map E.164 number (e.g. +33633348273) to the SIP URI of userSIP. Alternatively the response can also contain a NS record.
|
1b570a6648bd6e802a749e39655a3b23
|
186 011-2
|
4.3.3.2.3 Node Configuration
|
The common ENUM solution should be configured to support a proper resolution of E.164 TNs into SIP URIs as defined in GSMA PRD IR.67 [i.5], clause 5.44 with reference to RFC 3761 [i.4] and RFC 3403 [i.6].
|
1b570a6648bd6e802a749e39655a3b23
|
186 011-2
|
4.3.4 Test Configurations
|
The following architectural test configurations are referenced in the IMS NNI interoperability TDs in the present document. They are intended to give a general rather than a specific view of the required IMS core network SUT(s) connectivity and associated UE(s), AS(s), and DNS(s). NOTE: Note that in the following figures observable interfaces are indicated as a solid line, non-observable interfaces indicated as dashed lines, and IBCFs are assumed to act in a "pass-through" mode if topology hiding is not required by a test description. In addition, local DNS servers are not shown. ETSI ETSI TS 186 011-2 V4.1.3 (2012-05) 20 HSS HSS UE B Mx IMS A IMS B Gm PCO PO Roaming Registration CF_ROAM_REG IBCF A P-CSCF I-CSCF S-CSCF IBCF A PO PO Mx Ic Precondition: Different network operators performing origination and termination, UE_B roaming in visited network A (ROAM). UE_B not yet registered (REG), neither UE_A nor AS involved, a common interconnect ENUM DB and local ENUM is involved, IBCF is involved but no topology hiding performed. Test configuration for: Registration requests and responses from UE_B Example: REGISTER prior to IMS VoIP voice call from UE_B ENUM DB Figure 1: CF_ROAM_REG HSS HSS UE A UE B Mx IMS A IMS B Gm PCO Gm PCO PO Interworking Call CF_INT_CALL IBCF A P-CSCF I-CSCF S-CSCF P-CSCF IBCF A S-CSCF I-CSCF PO PO Mx Ic Precondition: Different network operators performing origination and termination, both Ues or only UE_A in home networks (INT), both Ues registered, no AS, a common interconnect ENUM DB and local ENUM is involved, IBCF is involved, topology hiding may apply. Test configuration for: Requests and responses between UE_A and UE_B in call (CALL) and messaging scenarios. Unsuccessful initiall requests and responses from UE_A (when UE_B is nor registered) Example: Initial INVITE in IMS VoIP voice call from UE_A to UE_B ENUM DB PO PO ENUM PO ENUM PO Figure 2: CF_INT_CALL ETSI ETSI TS 186 011-2 V4.1.3 (2012-05) 21 HSS HSS UE A UE B Mx IMS A IMS B Gm PCO PO Roaming Call CF_ROAM_CALL IBCF A P-CSCF I-CSCF S-CSCF P-CSCF IBCF A S-CSCF I-CSCF PCO PO PO Mx Ic Precondition: Different network operators performing origination and termination, UE_B roaming (ROAM) via IMS_A, UE_A in home network, both Ues are registered, no AS, a common interconnect ENUM DB and local ENUM is involved, IBCF is involved, topology hiding may apply. Test configuration for: Requests and responses between UE_B and UE_A in call (CALL) and messaging scenarios Example: Initial INVITE in IMS VoIP voice call from UE_B to UE_A ENUM DB Gm Figure 3: CF_ROAM_CALL HSS HSS UE A UE B Mx IMS A IMS B Gm PCO Gm PCO PO Interworking Application Server CF_INT_AS IBCF A AS A P-CSCF I-CSCF S-CSCF P-CSCF IBCF A S-CSCF I-CSCF PCO ISC PCO AS B ISC PO PO Mx Ic Precondition: Different network operators performing origination and termination, UE_A and UE_B in home networks INT), both UEs registered, AS for UE_A and UE_B (AS), a common interconnect ENUM DB and local ENUM is involved, IBCF is involved, topology hiding may apply. Test configuration for: Requests and responses between ASes and UEs Example: Initial INVITE in IMS VoIP voice call unconditionally forwarded to UE_B by AS_A (CFU), AS_A acts as routing AS ENUM DB Figure 4: CF_INT_AS ETSI ETSI TS 186 011-2 V4.1.3 (2012-05) 22 HSS HSS UE A UE B Mx IMS A IMS B Gm PCO Gm PCO PO Roaming Application Server CF_ROAM_AS IBCF A AS A I-CSCF S-CSCF P-CSCF IBCF A S-CSCF I-CSCF PCO ISC PCO AS B ISC PO PO Mx Ic Precondition: Different network operators performing origination and termination, UE_B roaming (ROAM) via IMS_A, UE_A in home network, both Ues are registered, AS for UE_A and UE_B may be involved (AS), a common interconnect ENUM DB and local ENUM is involved, IBCF is involved, topology hiding may apply. Test configuration for: Requests and responses between AS_B and UEs Example: Initial INVITE in IMS VoIP voice call unconditionally forwarded to UE_B by AS_B (CFU), AS_B acts as routing AS ENUM DB UE B P-CSCF Gm PCO Figure 5: CF_ROAM_AS HSS HSS UE A UE B IMS A IMS B Gm PCO Gm PCO Interworking Conference Server CF_INT_CONF_AS P-CSCF MRFC S-CSCF P-CSCF I-CSCF PCO ISC PO Mw Precondition: Different network operators performing origination and termination, both Ues or only UE_A in home networks (INT), both UEs registered, CONF AS is involved in IMS_A, a common interconnect ENUM DB and local ENUM is involved, IMS_A and IMS_B both include MRFC and MRFP Test configuration for: Requests and responses between UE_A and UE_B in an Ad-hoc Conference call (CONF_CALL) Example: Initial INVITE from UE_A to initiate an ad-hoc Conference call in IMS_A, and subsequent invitation to UE_B to join (via REFER method from UE_A) ENUM DB MRFC Conf AS A Mb S-CSCF MRFP I-CSCF MRFP Figure 6: CF_INT_CONF_CALL ETSI ETSI TS 186 011-2 V4.1.3 (2012-05) 23 HSS UE A IMS A Gm PCO IPTV CF_IPTV P-CSCF I-CSCF PCO ISC Precondition: UE_A registered in home network, IPTV_AS involved Test configuration for: Requests and responses between UE_A and IPTV AS Example: Initial INVITE from UE_A to initiate an IPTV Broadcast session S-CSCF IBCF IPTV AS Figure 7: CF_IPTV HSS UE A Mx IMS A Legacy Network Gm PCO PO PSTN Interworking CF_PSTN MGCF AS A P-CSCF S-CSCF I-CSCF PCO ISC PCO ISC PO E1 Precondition: Different network operators performing origination and termination, UE_A and UE_B in home networks INT), both UEs registered, AS for UE_A and UE_B (AS), a common interconnect ENUM DB and local ENUM is involved, IBCF is involved, topology hiding may apply. Test configuration for: Requests and responses between ASes and UEs Example: Initial INVITE in IMS VoIP voice call unconditionally forwarded to UE_B by AS_A (CFU), AS_A acts as routing AS ENUM DB ISDN PSTN Figure 8: CF_PSTN ETSI ETSI TS 186 011-2 V4.1.3 (2012-05) 24
|
1b570a6648bd6e802a749e39655a3b23
|
186 011-2
|
4.4 Use Cases
|
Use cases are the basis for interoperability test descriptions. Each use case defines both a generic test sequence, i.e. a set of user stimuli and observations for any number of involved IMS external entities (IMS UE, DNS Server, and AS), and a monitor view of all the resulting messages exchanged at the outer IMS core network interfaces, i.e. a call flow for user, Gm, Mw, Ic, DNS, and ISC interfaces. The test sequence and call flow are correlated using grey shading. For call and messaging related use cases presented in this clause that involve UE interaction it is assumed to follow the registration and subscription procedure described in clause 4.2.4 for each UE involved in the test. These procedures are not shown here to reduce the size of the call flows. Test descriptions defined in clause 4.5 then reference and specialize one of the use cases presented in this clause, i.e. generic test sequence and call flow, according to the needs of the one or more test purposes which are associated with a test description.
|
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