Rick Gentile
Ethernet Packet Handling Gets Prioritized
August 2008
One of the advantages you have with Blackfin is that you can choose from multiple products that come with an Ethernet peripheral integrated with the processor, such as the BF536, BF537, and some of our BF52x products. In past columns I’ve talked about various software stack options that currently run on Blackfin. In addition to a port of the LwIP (lightweight TCP/IP) stack provided with VisualDSP++ and the stack provided with uClinux, an extensive range of products is available from our third parties.
Blackfin and Ethernet already are used in such a wide variety of application spaces that it is exciting to see new areas still emerging. One area I want to tell you about is networked industrial control. The challenge in this space is getting the best of both of worlds out of Ethernet. That is, supporting real-time traffic -- without having to alter the underlying protocols -- at the same time as supporting non-real-time packets for routine TCP/IP activity.
Responding to this need for more responsive industrial networking systems, Quadros Systems, Inc., a Blackfin ecosystem partner, has developed a Prioritized Ethernet Framework. This framework allows the RTXC™ Quadnet TCP/IP Software to give prioritized treatment to preferred networking content. It further augments the benefits (discussed in a past column) of using the Quadros RTOS to help you develop and manage control and signal processing on the same processor.
Bill Dittmann, chief engineer with Quadros, summarizes the problem they are addressing this way: “The challenge for many networked embedded systems is there is no way to distinguish critical packets from the large volume of non-real-time Ethernet traffic. Ethernet packets are processed on a first-come, first-served basis. Important packets are left to wait while the packets that arrived ahead of them are processed. For embedded systems this leads to systems that are not responsive, or worse, fail to meet essential deadlines.”
The Prioritized Ethernet Framework is available as an add-on component to the RTXC Quadnet TCP/IP package. It provides packet sorting in the data link layer using the VLAN tag on the packet header to determine the priority level. The framework uses individual sockets tied to specific priority levels, and each priority level processes packets within a different RTXC Quadros RTOS task. This ensures the packets have preference in processing all the way through the TCP/IP stack.
To make your job easier, Quadros Systems also offers engineering services to adapt the framework to specific applications.
Get more information about RTXC Quadnet TCP/IP software or other Quadros products.
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Quadros and RTXC are trademarks of Quadros Systems, Inc.