Ethernet on the 40G backplane

Shortly after adoption of the IEEE 802.3ap specification for backplane Ethernet, the PICMG 3.1 Revision 2.0 subcommittee began work in early 2008 to integrate the backplane definitions into the ATCA specification family. This effort has proved challenging as the IEEE defined the characteristics of the channel based on hypothetical test points at either end, but did not address the details and complexities of applying that channel model to an open, multi-vendor, bladed platform ecosystem such as ATCA.

As RadiSys has helped sha­pe this process since the very beginning, here’s some history on how Ethernet backplane has evolved from a PICMG perspective:

  • The original ATCA PICMG specifications defining an Ethernet backplane interconnect predated the IEEE 802.3ap specification, which formally defined backplane Ethernet within IEEE.
  • PICMG 3.1 Revision 1.0 defined 1Gb (1000BASE-BX) and multi-lane 10Gb (10GBASE-BX4) Ethernet interfaces that were based on underlying 1.25Gbd and 3.125Gbd multi-lane electrical signaling rates.
  • Today’s 10Gb Ethernet ATCA systems are all built based upon the PICMG 3.1 R1.0 standard.  The IEEE 802.3ap-2007 specification defined backplane Ethernet for 10Gb serial Ethernet (10GBASE-KR) as well as formalized definitions for multi-lane 10Gb (10GBASE-KX4) and 1Gb (1000BASE-KX) Ethernet.
  • More recently, IEEE 802.3ba-2010 defined how 4 10GBASE-KR ports are combined to create a 40GBASE-KR4 interface.

So what does this history and today’s ongoing work mean for Ethernet on the 40G backplane? Check back on the RadiSys blog in the coming weeks as we continue the discussion.

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