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 specifies the definition of Profile TC43212. The TC43212 profile is in the TC group which supports Transport protocol classes 0 and 2.

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

TC43212

Connection-mode Transport Service over Connection-mode Network Service over ISDN - Packet mode service - B-channel permanent access - Virtual Call (VC) without use of Q.931.

NOTE - At the date of publication, 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 set up in support of 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 end system configurations to which TC43211 p rofile is applicable.

The reference End System is directly attached to the ISDN at an S/T reference point of a Basic or a Primary Rate Access.

This part of ISO/IEC ISP 10609 specifies the required functions from th e supporting protocol stack shown in Figures 2 and 3.

At layer 1, CCITT I.430 is used for ISDN basic access and CCITT I.431 is used for primary rate access. At layer 2, CCITT Q.921 provides the LAPD Data Link procedures for the D-channel and ISO 7776 provides the LAPB Data Link procedures for the B-channel. At layer 3, CCITT Q.931 signalling procedures are used on the D- channel, and ISO/IEC 8208 packet layer protocol is used in DTE/DCE mode on the B-channel. The provisions of ISO/IEC 8878 apply with regard to the mapping of the CONS primitives and parameters to and from the elements of the ISO/IEC 8208 packet layer protocol.

In receiving a call, the reference end system implements two protocol pillars below layer 4. One pillar is used over the ISDN D-channel for channel selection. The other is used over the B- channel for establishing, maintaining and clearing virtual calls , and for information transfer itself. In making a call, it implements only latter protocol.

In making a call, Network Service connection establishment is a single stage process, involving the establishment of a virtual call. (But, the Data Link layer connection needs to be established by user or PH.)

In receiving a call, Network Service connection establishment is a multi-stage process; the first stage is the channel selection using D-channel call control procedure, the next is the establi shment of the ISO 7776 Data Link layer over the B-channel (if not already established), finally the virtual call is established.

Network Service connection release is a single stage process, involving the release of a virtual call.