General

ISO/IEC ISP 12067 is applicable to interworking units concerned with operating in the Open Systems Interconnection (OSI) environment. It specifies a combination of OSI base standards that collectively provide a relay function for the connection-mode Network Service.

This part of ISO/IEC ISP 12067 defines the RB51.1121 profile, which is applicable to an interworking unit operating between CSMAKD LAN subnetworks and PSDNs using virtual calls over a digital data circuit / CSDN leased lint pcrmanent access.

Position within the taxonomy

The taxonomy of profiles is defined in ISO/IEC TR 10000-2. This part of ISO/IEC ISP 12067 defines the profile:

• RB51.1121 Relaying the connection-mode Network Service between CSMA/CD LAN subnetworks and PSDNs using virtual calls over a digital data circuit / CSDN leased line permanent access.

Scenario

Figure 1 illustrates the contiguration of systems to which the RB51.1121 profile is applicable. The figure shows two reference points, but an implementation of this profile may include more attachments to CSMA/CD LANs and PSDNs, with a reference point at each.

As this profile is a member of the RB group, it is intended that a conforming implementation is capable of interworking with other profiles of the RB group and with end systems implementing profiles from the TB, TC, TD and TE groups or the UB group, provided that suitable relays are in place in the case of those members of these groups which relate to different elements of the subnetwork taxonomy.

This profile specifies the required functions from the supporting protocol stack shown below.