1

Scope

1.1

General ISO/IEC ISP 10609 is applicable to end systems concerned with operating in the Open Systems Interconnection (OSI) environment. It specifies a combination of OSI standards, which collectively provide the connection-mode Transport Service using the connection-mode Network Service.

This part of ISO/IEC ISP 10609 defines the profile TD4111. The TD4111 profile is in the TD Group which supports Transport protocol class 0.

1.2

Position within the taxonomy The taxonomy of OSI profiles is defined in ISO/IEC TR 10000-2. This part of ISO/IEC ISP 10609 defines the profile:

TD4111

Connection-mode Transport Service over connection-mode Network Service - ISDN B-channel permanent service - X.25 DTE to DTE op eration.

NOTE - At time of publication of this part of ISO/IEC ISP 10609, there is no difference from a terminal point of view between ""permanent"" and ""semi-permanent"" connections. However, ITU-T may define a procedure that would allow an ISDN terminal to have a semi-permanent connection in support of a permanent B-channel. At that time, amendments to this profile may be necessary. This profile uses the term ""permanent"".

This profile may be combined with any A-profile at the A/T boundary.

1.3

Scenario Figure 1 illustrates the configuration of systems to which the TD4111 profile is applicable.

The reference end system communicates with the remote end system through an Integrated Services Digital Network (ISDN). The reference end system is directly attached to the ISDN at an S/T reference point.

This part of ISO/IEC ISP 10609 specifies the required functions from the supporting protocol stack shown in figure 2.

At layer 1, CCITT I.430 is used for ISDN basic rate access and CCITT I.431 is used for primary rate access. At layer 2, ISO 7776 provides the LAPB Data Link procedures. At layer 3, ISO/IEC 8208 packet layer protocol is used in DTE/DTE mode. The provisions of ISO/IEC 8878 apply with regard to the mappings of the CONS primitives and parameters to and from the elements of the ISO/IEC 8208 packet layer protocol.

Network Service connection establishment and release are single stage processes, involving the establishment or release of a virtual call. This assumes that the Data Link layer connection is already established.