COBO close specification work

Created September 17, 2017
Applications and Research

The module specification work of the Consortium for On-board Optics (COBO) is nearly complete. A draft specification defining the mechanical aspects of the embedded optics design – the dimensions, connector and electrical interface – is already being reviewed by the consortium’s members.

“The draft specification encompasses what we will do inside the data centre and what will work for the coherent market,” said Brad Booth, chair of COBO and principal network architect for Microsoft’s Azure Infrastructure.

COBO was established in 2015 to create an embedded optics multi-source agreement (MSA). On-board optics have long been available but until now these have been proprietary solutions.

The COBO design supports 400-gigabit multi-mode and single-mode optical interfaces. The electrical interface chosen is the IEEE-defined CDAUI-8, eight lanes each at 50 gigabits implemented using a 25-gigabit symbol rate and 4-level pulse-amplitude modulation (PAM-4). COBO also supports an 800-gigabit interface using two tightly-coupled COBO modules.

The consortium has also defined three module categories that vary in length. The module classes reflect the power envelope requirements; the shortest module supports multi-mode and the lower-power module designs while the longest format supports coherent designs. “The beauty of COBO is that the connectors and the connector spacings are the same no matter what length [of module] you use,” said Booth.

The main coherent application envisaged for COBO is the Optical Internetworking Forum’s 400ZR specification that is under development.

Booth says the COBO specification will likely need a couple more members’ reviews before its completion. “Our target is still to have this done by the end of the year,” he said.

By Roy Rubenstein

See also:

COBO MSA website:

Gazettabyte: Cobo targets year-end to complete specification


This article was written
by Roy Rubenstein

is the editor of and has been researching and writing about the telecom and semiconductor industries for over 20 years.