A Network Layer datagram protocol from the International Organization for Standardization (ISO) for use over OSI (Open Systems Integration) networks and specified in ISO 8473. CLNP is very similar to Internet Protocol (IP).The datagram size is the same as IP, and there are similar mechanisms for fragmentation, error control, and lifetime control. CLNP, however, has an address space of 20 octets compared the IPv4 address space of only 4 octets. OSI networks have not been well accepted, however, and the OSI protocol stack has been relegated to the status of OSI Reference Model. See also datagram, error control, fragmentation, IP, ISO, lifetime control, Network Layer, OSI, OSI Reference Model, protocol, and protocol stack.