Is DCB Ready for the Big Time?

Until now, Data Center Bridging (DCB) implementations have been fraught with interoperability issues, mainly due to varying Data Center Bridging Exchange Protocol (DCBX) implementations. Now that vendors are expected to converge on the latest IEEE DCB standard, we expect great strides toward real interoperability.

Data Center Bridging was recently defined by the IEEE as a series of standards to enhance Ethernet in order to prevent frame loss during congestion periods and provide additional control over traffic streams. DCB consists of four technologies: Priority-based Flow Control (PFC), Enhanced Transmission Selection (ETS), Congestion Notification (CN) and DCBX. All four technologies can work together or independently. As a result of implementation issues and the hardware limitations of many DCB devices, interoperability has been a challenge. Specifically, DCBX has limited interoperability success due to vendor implementation of older versions of the IEEE standard.

DCBX is a mechanism used to negotiate the ETS, CN and PFC configurations. Since there are numerous older versions of the standard, many vendors have not adopted the same versions for implementation. There are at least four major different implementations in the wild right now including: Pre-CEE, baseline, early draft IEEE and final IEEE. None of these major versions can interoperate with one another, which causes DCB to be disabled. The IEEE DCB standards have been technically stable since November 2010.  For the upcoming Ethernet Alliance DCB plugfest, which will be hosted at the UNH-IOL, we anticipate that many vendors will come with the latest implementation of the IEEE standard, therefore allowing for full interoperability.  If you’re interested in learning more about the plugfest, please visit the lab’s upcoming test event webpage http://www.iol.unh.edu/pressroom/events/ or the plugfest information page on the Ethernet Alliance’s website: http://www.ethernetalliance.org/events/ieee_8021_data_center_bridging_dcb_interoperability_test_event.

Have you experienced interoperability issues with your company’s DCB devices?  If so, were implementation issues or different versions supported the root of the problem?

Mikkel Hagen, Senior Engineer

Ryan Zarick, R & D