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What is VPX?

Overview

VPX was originally standardised in 2007, based on serial fabrics for high bandwidth point-to-point communications.  It has become the de-facto standard for highly rugged multiprocessor-based equipment at the edge, it is widely used for defence applications but due to high reliability has also been deployed in transportation, industrial and power generation scenarios.

History

VPX was originally standardised in 2007, based on serial fabrics for high bandwidth point-to-point communications.  Owned By VITA, and as a successor of the VME standard, the original VPX (VITA 46) standard was created to deliver more robust, high-speed performance for data-intensive applications. VITA’s goal was to provide a future proofed standard that would be used to create rugged solutions for applications in the military, aerospace, transportation and industrial markets.  

Based on key customer feedback working groups were formed in 2009, with a goal to improve the interoperability of 3U and 6U VPX boards through the implementation of predefined profiles.  Key goals were to lower the risk of adoption, expand the addressable market for VPX solutions and accelerate the deployment of VPX solutions into defense related applications. OpenVPX is a development of, and complementary to, VPX. The OpenVPX (VITA 65) Specification was initially ratified by ANSI in June 2010.

Even though OpenVPX was widely adopted, it was recognized that technology transitions were difficult because vendor specific choices caused system integrator challenges.  The two main ones being the mix of +5V and +12V power supplies and the proliferation of vendor specific user I/O pin implementations.  In response to the tri-service memo signed by the secretary for the army, navy and air force, momentum has been rapidly growing and has driven changes to VITA 65.0 and VITA 65.1 standards in 2019, 2021 and again in 2023. In particular, the SOSA OpenGroup’s publication of the SOSA Technical Standard has been instrumental in driving changes back into the VITA 65 standards to significantly improve the total cost of ownership by enabling easier technology refresh cycles, improving interoperability, increasing the cadence of innovation, and enhancing competition for Plug In Cards.

VPX Advantages

The VPX standard is an ideal basis created specifically for products widely deployed in military and aerospace environments due to their robust, high performance nature.  Rugged variants are usually available based on a rigorous testing cycle to ensure reliability in  severe operating temperatures, shock, vibration, altitude and other environmental factors.

The OpenVPX framework defines the clear interoperability points necessary for integration between Module to Module and Module to Backplane and Chassis. The Specification describes the technical implementation details for 3U and 6U VPX payload and switch modules in an attempt to provide clear guidance on how to build interoperable computing and communication platforms.

Key choices to consider include: 

  • 3U or 6U Plug in card size. 3U is significantly more popular due to the ease of packaging and ruggedization

  • Backplane speed. Depending on the VPX connector chosen, it is now routine to see connections between boards in a VPX system running at 25 Gbit/s

  • Choice of high-speed serial fabrics.  Traditional VPX systems had a wide choice of  data plane including PCI Express, RapidIO, Ethernet and others.  To be aligned to the SOSA Technical specification all payload cards have 40/100G Ethernet on the dataplane, 10G Ethernet on the control plane and typically PCI Express on the expansion plane

  • Direct coaxial (VITA 67) and fibre (VITA 66) connections.  This is a key differentiator with VPX, many backplanes have cut outs for RF and fibre incoming connections directly to the payload board

  • Alignment/keying blocks.  Used to make sure that plug in cards can only go into the right slot in a system

  • Cooling methodology.  Most VPX deployments are conduction-cooled according to the VITA 48.2 standard.  Recent needs to cool significantly more powerful VPX cards have resulted in the production of Air Flow Through variants, usually to the VITA 48.8 standard.  Other cooling methodologies exist including alternative Air Flow Through and Liquid colling standards

The Future

Due to the high level of adoption and promotion, there is a constant push for newer, more progressive innovations. We have seen, in the past 10 years or so, a great deal of development towards ever higher connection speeds, leading to PCIe Gen 5 and 100GbE capable products today. There is a great deal of work going on behind the scenes which will lead to more progression.