IGP is a protocol used in a company, organization, or school environment, that is, in an autonomous system (AS).
UDP (User Datagram Protocol) allows datagrams to be sent over the network without establishing a connection, as it contains sufficient address information in the header of the datagram. Also, there is no confirmation or flow control, so the packages may be in front of each other and it is not known whether it is correct because there is no delivery or purchase confirmation.
The OSI model is a reference framework for defining interconnection architectures for communication systems. It is a functional guide for communication tasks and therefore does not specify a communication standard for such tasks. However, many standards and protocols comply with the guidelines of the Open Systems Interconnection Model.