RTnet, an open source hard real-time network protocol stack for deterministic data transmission over standard Ethernet, has reached an important milestone: version 0.5.0 has been released today, with non real-time tunneling, easier installation, support for more NICs, and more.

This version introduces the Virtual NIC feature for tunneling non real-time traffic through RTnet-enabled networks, prioritized send queues, and an advanced real-time buffer pool management. The installation process has been simplified, and the number of supported network cards has been further extended.

RTnet runs on top of RTAI, a hard real-time extension for Linux, and aims to enable the use of cheap, fast Ethernet hardware in distributed control systems. RTnet implements UDP/IP, ICMP, and ARP in a deterministic way.

RTNet is already being used successfully on x86 and PPC platforms, but has been designed without architecture dependencies. A BSD socket API is provided to access the real-time enabled UDP/IP protocol stack. In a dedicated network segment, the optional media access control layer, RTmac, can enforce a deterministic packet transmission, currently based on a Time Division Multiple Access (TDMA) protocol. RTnet also includes a mechanism to tunnel non real-time traffic like TCP/IP over RTmac, thus allowing a “single-cable” solution for connecting control systems.

Some possible applications for RTnet include fieldbus replacements, distributed real-time computing, and video/audio streaming.

The RTnet protocol has been integrated into Ethereal (0.9.15) to support the analysis of real-time networks.

 
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