The authority for assigning the host number part of the IP address resides with the organization which controls the network identified by the network number. The addressing scheme is described in detail in Addressing . We will describe the most important aspects of the protocol suite in this and the following chapters. This layered representation leads to the term protocol stack which is synonymous with protocol suite. Functional comparisons cannot easily be extracted from this, as there are basic differences in the layered models used by the different protocol suites.
Application is a user process cooperating with another process on the same or a different host.
These are discussed in detail in Application Protocols . It is a connectionless protocol which doesn't assume reliability from the lower layers. IP does not provide reliability, flow control or error recovery. These functions must be provided at a higher level, either at the Transport layer by using TCP as the transport protocol, or at the Application layer if UDP is used as the transport protocol. A message unit in an IP network is called an IP datagram .