The Transport Driver Interface or TDI is the protocol understood by the upper edge of the Transport layer

Transport layer

In computer networking, the transport layer or layer 4 provides end-to-end communication services for applications within a layered architecture of network components and protocols...

 of the Microsoft Windows kernel network stack.

Transport Providers are implementations of network protocols such as TCP/IP, NetBIOS

NetBIOS

NetBIOS is an acronym for Network Basic Input/Output System. It provides services related to the session layer of the OSI model allowing applications on separate computers to communicate over a local area network. As strictly an API, NetBIOS is not a networking protocol...

, and AppleTalk

AppleTalk

AppleTalk is a proprietary suite of protocols developed by Apple Inc. for networking computers. It was included in the original Macintosh released in 1984, but is now unsupported as of the release of Mac OS X v10.6 in 2009 in favor of TCP/IP networking...

.

When user-mode binaries are created by compiling and linking, an entity called a TDI client is linked into the binary. TDI clients are provided with the compiler

Compiler

A compiler is a computer program that transforms source code written in a programming language into another computer language...

. The user-mode binary uses the user-mode API of whatever network protocol is being used, which in turn causes the TDI client to emit TDI commands into the Transport Provider.

Typical TDI commands are TDI_SEND, TDI_CONNECT, TDI_RECEIVE.

The purpose of the Transport Driver Interface is to provide an abstraction layer, permitting simplification of the TDI clients.