This Recommendation | International Standard specifies a protocol that is used to provide the connectionless-mode Network service described in ITU‑T Rec. X.213 ISO/IEC 8348 and to perform certain Network layer management functions. The protocol relies upon the provision of an underlying connectionless-mode service by real subnetworks and/or data links. The underlying connectionless-mode service assumed by the protocol may be obtained either directly, from a connectionless-mode real subnetwork, or indirectly, through the operation of an appropriate Subnetwork Dependent Convergence Function (SNDCF) or Protocol (SNDCP) over a connection-mode real subnetwork, as described in ISO/IEC 8648. This Recommendation | International Standard specifies the operation of the protocol with respect to a uniform, abstract "underlying subnetwork service". Other Recommendations | International Standards specify the way in which this "underlying subnetwork service" is obtained from real subnetworks, such as those which conform to ISO/IEC 8802 or ISO/IEC 8208. The "underlying subnetwork service" may be obtained from real subnetworks other than those that are specifically covered by the other Recommendations | International Standards.

This Recommendation | International Standard specifies:

The procedures are defined in terms of:

This Recommendation | International Standard also provides the PICS proforma for this protocol, in compliance with the relevant requirements, and in accordance with the relevant guidance, given in ITU‑T Rec. X.290 ISO/IEC 9646‑1.