Lineo has announced RTnet, an open source modification to the existing Linux networking subsystem that enables hard real-time networking over standard IP networks. Although real-time networking capability is currently provided by a number of proprietary operating systems, hard real-time networking has not previously been available for Linux.

According to David Schleef, RTnet principal developer, “RTnet is a modification of the existing Linux networking subsystem to provide real-time performance for sending and receiving packets over standard IP networks. The IP, ICMP, and UDP protocols are supported. TCP is not supported, because it is not possible to make it real-time. The programming interface is identical to the standard sockets interface, making it (almost) source code compatible with user-space applications that use Linux networking. Since it is based on Linux networking, RTnet should be able to communicate with existing network stacks. RTnet can be used with either RTLinux-2.3 and RTAI-1.3, and may be distributed and modified under the Gnu GPL. The code is still beta, but it is stable enough to be used in applications.”

RTnet Features Summary

• Supports the IP, ICMP and UDP protocols. (Note: The nature of the TCP protocol prevents it from being applicable to real-time networking.)
  
• Provides a sockets implementation for use by real-time tasks.
  
• Uses a programming interface that is nearly identical to the standard sockets interface. Developers who are familiar with normal UDP-socket networking should find porting easy.
  
• Based on Linux networking and, therefore, should communicate with existing network stacks.
  
• Works with Linux-2.2.x kernels in connection with either of the predominant Linux real-time extensions, RTAI v1.3 or RTLinux v2.3.

The current status of RTnet is “stable and ready to be used in applications, however this code should be considered beta until a formal release.” Further information regarding RTnet installation, hardware support and associated issues can be found in the RTnet package readme files. The beta version of RTnet is currently available for public download via ftp, here.

RTnet is an open source project that is freely distributable under the GNU General Public License. The principal developer and maintainer of RTnet is David Schleef ([email protected]). Continued RTnet development is being supported by Lineo. Open source projects funded or otherwise supported by Lineo and its employees are collected at a special website, located here.

 
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