Information Technology - Protocol for Providing the Connectionless-Mode Network Service: Protocol Specification Series X: Data Networks and Open System Communication _ Open System Interconnection - Connectionless-Mode Protocol Specifications
This Recommendation I International Standard specifies a protocol that is used to provide the connectionless-mode
Network service described in ITU-T Rec. X.213 I ISOAEC 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 ISODEC 8648. This Recommendation I International Standard specifies the operation of the protocol with
respect to a uniform, abstract “underlying subnetwork service”. Other Recommendations I International Standards
specifj the way in which this “underlying subnetwork service” is obtained from real subnetworks, such as those which
conform to ISOAEC 8802 or ISOíiEC 8208. The “underlying subnetwork service” may be obtained from real
subnetworks other than those that are specifically covered by the other Recommendations I Intemational Standards.
This Recommendation I International Standard specifies:
a)procedures for the connectionless transmission of data and control information from one Network entity
to one or more peer Network entities;
b)the encoding of the Protocol Data Units (PDUs) used for the transmission of data and control information,comprising a variable-length protocol header format;
c)procedures for the correct interpretation of protocol control information; and
d)the functional requirements for implementations claiming conformance to this Recommendation 1
international Standard.
The procedures are defined in terms of:
a)the interactions among peer Network entities through the exchange of protocol data units;
b)the interactions between a Network entity and a Network service user through the exchange of Network
service primitives; and
c)the interactions between a Network entity and an abstract underlying service provider through the
exchange of service primitives.
This Recommendation I 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 I ISOAEC 9646-1.