Windows 2000 IrDA Infrared Support Mechanism

Microsoft Windows 2000 provides native support for infrared communications using an integrated IrDA (Infrared Data Association) protocol architecture built directly into the operating system's networking subsystem. This article examines the core mechanisms Windows 2000 uses to handle IrDA data transfers, focusing on the driver stack, the Windows Sockets interface, and higher-level communication services like Wireless Link and IrTran-P.

The IrDA Network Driver Architecture

In Windows 2000, infrared communication is treated primarily as a networking protocol rather than a standard serial port connection. The architecture operates through the Network Driver Interface Specification (NDIS) version 5.0:

  • IrDA NDIS Miniport Drivers: Hardware manufacturers provide NDIS miniport drivers that communicate directly with the infrared transceiver hardware, whether built directly onto the motherboard (Super I/O chips) or connected through external serial or USB dongles.
  • Core Protocol Stack: The operating system includes a native IrDA stack that implements key specifications established by the Infrared Data Association:
    • IrLAP (Infrared Link Access Protocol): Provides reliable data transfer, handles device discovery, and manages hardware-level handshaking and frame sequencing.
    • IrLMP (Infrared Link Management Protocol): Manages multiplexing, allowing multiple concurrent client connections over a single physical link. It also includes the Information Access Service (IAS), which functions as a service directory for peer devices.
    • Tiny TP (Tiny Transport Protocol): Handles flow control, segmentation, and reassembly of data packets across the link.

Windows Sockets (AF_IRDA)

The primary programming interface for IrDA transfers in Windows 2000 is Windows Sockets (Winsock). The operating system introduces the AF_IRDA address family, which exposes IrDA endpoints through standard socket APIs. Developers and system services use standard socket calls (socket, bind, connect, send, recv) tailored for infrared discovery and transport. This abstraction allows applications to discover remote IrDA devices and open bidirectional, reliable byte streams without low-level hardware control.

High-Level File Transfer and Device Protocols

Windows 2000 implements several application-level services directly over the IrDA protocol stack:

  • Wireless Link (IrXfer): A built-in utility that monitors the infrared port for peer devices. When another IrDA-capable computer moves within range, Windows 2000 alerts the user and displays an icon in the system tray, allowing drag-and-drop file transfers via an underlying object-exchange mechanism.
  • IrTran-P (Infrared Transfer Picture): A dedicated protocol and service inside Windows 2000 specifically designed to receive digital photographs directly from compliant digital cameras without requiring proprietary camera drivers.
  • IrCOMM: Although Windows 2000 prioritizes Winsock-based communication, it provides support for communicating with legacy devices expecting serial or parallel cable emulation over infrared.