COBO offers Release 1.0 specifications for onboard optical modules

Three years after its founding, the Consortium for On-Board Optics (COBO) used OFC 2018 in San Diego last month as a stage on which to debut its long-awaited Release 1.0 specifications. The specifications cover three classes of onboard optical modules, backed by a pair of electrical interfaces. The optical modules will support transmission rates up to 800 Gbps. COBO expects the modules to meet a range of data center network requirements, including those that would require coherent transmission.

Three years after its founding, the Consortium for On-Board Optics (COBO) used OFC 2018 in San Diego last month as a stage on which to debut its long-awaited Release 1.0 specifications. The specifications cover three classes of onboard optical modules, backed by a pair of electrical interfaces. The optical modules will support transmission rates up to 800 Gbps. COBO expects the modules to meet a range of data center network requirements, including those that would require coherent transmission.

The specification defines requirements for electrical, mechanical, optical, and thermal parameters for embedded optical modules. The specification supports optical interfaces based on the recently completed IEEE 802.3bs-2017 standard, which covers both 400 Gigabit Ethernet and single-mode 200 Gigabit Ethernet applications.

Release 1.0 defines each of the three module classes in combination with the two electrical interfaces – one eight lane, the other sixteen lane, based on 25-GBaud PAM4 per lane – to meet both 1x400G and 2x400G requirements. The latter can be in either independent or integrated format. The three classes feature a common host connector and width of 20 mm for the x8 configuration and 36 mm for the x16 form factors. The three classes vary in length, with Class A at 30 mm, Class B at 40 mm, and Class C at 60 mm. The varying lengths provide the necessary packaging room to contain the optics and electronics necessary to meet targeted reach requirements.

The resulting modules could be applied to a variety of applications. COBO has developed a reference application that details a 1RU 12.8-Tbps data center switch with either front-to-back or back-to-front airflow that was used to develop the specifications. COBO use cases could include coherent transmission. A whitepaper COBO distributed at OFC described the coherent working group within COBO as evaluating the OIF's 400ZR specification for such applications. Speaking at the show from COBO's booth, Hugues Tournier, member of scientific staff, hardware development at Ciena, said his company has interest in coherent-enabled COBO embedded modules.

Looking ahead, COBO envisions future iterations of the specifications to leverage the OIF's Common Electrical Interface for 112-Gbps PAM4 very short reach (CEI-112G-VSR-PAM4) work as well as that of the IEEE 802.3 100G Electrical Lane interface study group, with an eye toward support of 1.6-Tbps transmission. In the shorter term, COBO plans to enable the ability to test compliance and interoperability of modules based on the specifications as well as further enable market adoption of such modules.

The Release 1.0 specification can be downloaded from http://onboardoptics.org/.

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