5 BC context

32.1543GPPBackward and Forward Compatibility (BFC)Concept and definitionsRelease 17Telecommunication managementTS

5.1 General

This clause defines the context under which the requirements specified in the present document are applicable.

The word ‘old’ qualifies the related entity (i.e. the AlarmIRP of an IRPAgent instance or Alarm IRPManager) that is using an older 3GPP IRPVersion (called old version). The word ‘new’ qualifies the related entity that is using a newer (upgraded) 3GPP IRPVersion.

EXAMPLE: A hypothetical 3GPP TS 32.123 V6.0.0 is considered the old version with reference to 3GPP TS 32.123 V6.1.0. The two versions in question can belong to the same or different major releases (e.g. Rel-5 or Rel-6).

The box labelled EM in figure 5.1 conveys the same idea as the box of the same label in the System Context-A of other IRP specifications such as Alarm IRP IS 3GPP TS 32.111-2 [3].

One or all EM-labelled boxes of figure 5.1 can be interchanged with the NE‑labelled box (see System Context‑B of other IRP specifications such as Alarm IRP IS 3GPP TS 32.111-2 [3]). The NE entities are not shown in order to make the figure easier to read.

Figure 5.1: Overall BC System Context

In general, an IRPAgent instance may contain several Interface YyyIRP instances and associated supporting Yyy NRM IRPs (where one IRP can be for example Alarm IRP, Test Management IRP, or "Notification IRP", etc and where the other IRP can be for example Generic IRP). The Interface and NRM YyyIRP specifications of particular IRPVersion(s) together specify the behaviour of an Interface IRP and the supporting NRM IRP (s).

NOTE: The IRPVersion concept is related to the IRP.
The IRPVersion concept is not related to the IRPAgent as this may contain multiple IRPs.

Given this background, the BC issues are addressed at two separate but related levels as described in clauses 5.2 and 5.3.

5.2 IRP level

The two diagrams here illustrate conceptually the two possible contexts when we address BC at this IRP level.

Figure 5.2: Specification BC System Context

An YyyIRP instance supports a particular Interface IRPVersion and a particular set of NRM IRPVersions. An IRPManager uses a particular Interface IRPVersion and a particular set of NRM IRPVersions.

If an YyyIRP instance supports Interface IRPVersion-X and NRM IRPVersions-Y, then it can interact successfully with an IRPManager that uses the same IRPVersions. This is illustrated by the case of the "Old IRPManager" and the "Old IRPAgent" of the bottom diagram (and note that the diagram does not show the NRM IRP version support).

If this same YyyIRP instance upgrades its Interface IRPVersion-X to X2 that is BC to X, then it can interact successfully with an IRPManager that uses the Interface IRPVersion-X or IRPVersion-X2. The top diagram of figure 5.2 illustrates this case (and note that the diagram does not show the NRM IRP version support).

If this same YyyIRP instance upgrades its NRM IRPVersion-Y to Y2 that is BC to Y, then it can interact successfully with an IRPManager that uses the NRM IRPVersion-Y or NRM IRPVersion-Y2. The top diagram of figure 5.2 illustrated this case (and note that the diagram does not show the NRM IRP version support).

Given the above, the BC issues addressed at the present document level are:

– How to determine if an IRP IS or SS specification (Interface IRP or NRM IRP) is BC to an earlier version ?
This can be addressed in another way.
What are the BC-rules that the author of a 3GPP IRP specification should use to extend an old-version to produce a new version that can claim BC (to that old-version) ?

At this level, the specification author shall define BC-rules for each of the following:

– Interface IRP- Requirements.

– Interface IRP IS.

– Interface IRP SS(s).

– NRM IRP requirements.

– NRM IRP IS.

– NRM IRP SS(s).

– Data Definition IRP IS.

– Data Definition IRP SS(s).

One reason why the specification author addresses BC at this IRP level is that, for certain technologies, such as CORBA, it is possible that one entity using (compiles with) one IRP SS specification (i.e. the CORBA SS) while the other communicating entity using a new but BC version can interact successfully (such as the case of the IRPManager and IRPAgent-A of [REC-1]).

5.3 IRPAgent level

Figure 5.3 illustrates the two possible contexts when addressing BC at this IRPAgent level.

Figure 5.3: System/Implementation BC System Context

NOTE 1: An IRPAgent instance contains multiple YyyIRP instances such as AlarmIRP, NotificationIRP, TestManagementIRP, etc. Each YyyIRP instance implements/supports the corresponding YyyIRP specification of a particular IRPVersion.

Suppose IRPAgent-A contains YyyIRP of Interface IRPVersion-4, YyyIRP of Interface IRPVersion-5 and YyyIRP of Interface IRPVersion-6 and all IRPs support NRM IRPVersion-7 (see Note 2), this IRPAgent-A is BC if it can inter-operate successfully with the following:

– IRPManager 1 using Interface IRPVersion-4 or 3 using NRM IRPVersion-7 or 6.

– IRPManager 2 using Interface IRPVersion-5 or 4 using NRM IRPVersion-7 or 6.

– IRPManager 3 using Interface IRPVersion-6 or 5 using NRM IRPVersion-7 or 6.

NOTE 2: All IRPs contained by the same IRPAgent instance should support the same set of NRM IRPVersions.

It is anticipated that the IRPAgent level BC solution includes:

– An IRPAgent service allowing IRPManager to discover all the IRPAgent supported Interface IRPVersion(s).

– An IRPAgent service allowing IRPManager to discover the IRPAgent supported NRM IRPVersion(s).

– An IRPAgent service allowing IRPManager to discover the reference/address of the IRP instance (of the IRPAgent) supporting a particular Interface IRPVersion.

The two diagrams in figure 5.3 illustrate the two possible ways to support BC at this so-called IRPAgent level.

The IRPVersion-new needs not to be BC to IRPVersion-old. In the case that IRPVersion-new is BC to IRPVersion‑old, it is EM supplier’s choice if "IRP level" or "IRPAgent level" solution will be used to support BC. In the case that the IRPVersion-new is not BC to IRPVersion‑old, then the EM supplier will have no choice but to use "IRPAgent level" solution if it wants its EM to support BC.

NOTE 3: IRPAgent service supporting "discovery" (as stated by the above three bullets) is not illustrated in the two diagrams