Demystifying 40-GbE physical layer interfaces in data centers

Different supported interfaces from the port side to the backplane within a 40 Gigabit Ethernet data center system are described.

Content Dam Cim En Articles 2014 07 Synopsys Demystifying 40gbe Datacenters Leftcolumn Article Thumbnailimage File

Figure: Evolution of Ethernet speeds (Source: Synopsys)

A recent technical article from Synopsys, a producer of Ethernet ICs [integrated circuits], describes the different supported interfaces from the port side to the backplane within a 40 Gigabit Ethernet (40 GbE) system that would enable a cost-effective migration to higher bandwidth that can be deployed in today’s data centers.

"System and IC designers must understand the differences between the two port sides and the backplane electrical interfaces to select the SerDes PHY with the right capabilities for their respective applications," explains the article. "On the port side of a chassis, XFI and SFI are the two major single lane 10 Gigabit Ethernet (GE) electrical specifications defined for the XFP and SFP+ module form factors. On aggregated 10 GE, XLAUI and XLPPI electrical specifications are defined for the 40 GE CFP and QSFP module form factors."

The article continues, "Even though a PHY capable of driving a backplane may seem to be a superset PHY capable of driving both the port side and backplane channels, if the PHY is not designed and verified to support all three interfaces, it will not fully meet the electrical specifications required to drive a port side module and a backplane channel under all conditions and its use will result in interoperability issues, as each of these specifications have subtle requirement differences that must be designed to and verified."

The document concludes, "IC designers need reliable interface IP that is capable of supporting all three different electrical interfaces in a single SerDes PHY, independent of the channel type that is verified and licensed from a single IP vendor. This combination provides the ultimate flexibility, optimal cost and ROI, and time to market." Synopsys adds that its DesignWare Enterprise PHY IP "has the necessary features and capabilities to drive all three different 40 GE interfaces necessary for ASICs applications in data centers."

Full Article:Demystifying 40 Gigabit Ethernet Physical Layer Interfaces in Data Centers (

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