The PATTERNS scheduling tool was created to test the multi-plane concept of a Time Triggered Ethernet (TTE) network. The TTE network interface cards used in the Orion vehicle contain three physical network ports, referred to as planes. Each plane exists to serve as a redundant communication channel for each link in the network. The scheduler used prior to PATTERNS was the vendorprovided demonstration tool, TTE-demo-scheduler, which was unable to schedule Ethernet traffic in a manner that would allow the plane-specific and plane-independent tests required to be performed.

PATTERNS creates schedules for a TTE network, which is a network type requiring all devices on the network to have a configuration file created before communications can take place. PATTERNS uses a network configuration file created by the user to generate a number of XML files. This is done using a combination of helper scripts to generate output appropriate for the hardware and network PATTERNS: Panoptic Aspect Time Triggered Ethernet Robust Network Scheduler, Version 1.0 Lyndon B. Johnson Space Center, Houston, Texas specified. The XML files are used in conjunction with the hardware vendor’s Time Triggered Ethernet toolchain in order to generate low-level files to be loaded onto the physical hardware.

PATTERNS requires the user to create an input file that describes the network. Within that input file, the user specifies the switches and end systems (network interface cards) to be used in the network, as well as how all of the devices are physically connected together, including device physical port numbers. Once the hardware is specified, all of the Time Triggered messages are defined. Those definitions include the source device, destinations, and path through the network for each message. While PATTERNS can schedule any number of messages, the current hardware implementation has an upper limit of 4,096 messages.

This work was done by Jeremy Moreau of Johnson Space Center. MSC-25285-1


NASA Tech Briefs Magazine

This article first appeared in the January, 2015 issue of NASA Tech Briefs Magazine.

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