Connectionless Network Protocol (CLNP) is a connectionless network protocol of the Open System Interconnectsion( OSI) and thus equivalent to the IP protocol. The CLNP protocol is therefore sometimes also referred to as ISO-IP.
The header of the CLNP protocol contains similar data fields as the IP header. These include data fields for the source and destination addresses, fragmentation, checksum, and a Time-To-Live( TTL) field that ensures that data packets are destroyed after a specified time on the network. The CLNP address fields have a length of 20 bytes.
The CLNP protocol dates from 1986 and is described in RFC 994.