What is the relationship between the transport layer and the network layer?

Answer 1

In computing and telecommunications, the transport layer is the second highest layer in the four and five layer TCP/IP reference models, where it responds to service requests from the application layer and issues service requests to the Internet layer. It is also the name of layer four of the seven layer OSI model, where it responds to service requests from the session layer and issues service requests to the network layer. The definitions of the transport layer are slightly different in these two models. This article primarily refers to the TCP/IP model. See also the OSI model definition of the transport layer