Xilinx delivers 58G serdes and showcases a 112G test chip

In the first of two articles, electrical input-output developments are discussed, focussing on Xilinx’s serialiser-deserialiser (serdes) work for its programmable logic chips. In Part 2, the IMEC nanoelectronics R&D centre’s latest silicon photonics work to enable optical I/O for chips is detailed.

Part 1: Electrical I/O

Processor and memory chips continue to scale exponentially. The electrical input-output (I/O) used to move data on and off such chips scales less well. Electrical interfaces are now transitioning from 28 gigabit-per-second (Gbps) to 56Gbps and work is already advanced to double the rate again to 112Gbps. But the question as to when electrical interfaces will reach their practical limit continues to be debated. 

Gilles Garcia“Some two years ago, talking to the serdes community, they were seeing 100 gigabits as the first potential wall,” says Gilles Garcia, communications business lead at Xilinx. “In two years, a lot of work has happened and we can now demonstrate 112 gigabits [electrical interfaces].”

The challenge of moving to higher-speed serdes is that the reach shortens with each doubling of speed. The need to move greater amounts of data on- and off-chip also has power-consumption implications, especially with the extra circuitry needed when moving from non-return-to-zero signalling to the more complex 4-level pulse-amplitude modulation (PAM-4) scheme.  

PAM-4 is already used for 56-gigabit electrical I/O for such applications as 400 Gigabit Ethernet optical modules and by the leading edge 12.8-terabit capacity switch chips. Having 112-gigabit serdes at least ensures one further generation of switch chips and optical modules but what comes after that is still to be determined. Even if more can be squeezed out of copper, the trace lengths will shorten and optics will continue to get closer to the chip. 

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ONF advances its vision for the network edge

The Open Networking Foundation’s (ONF) goal to create software-driven architectures for the network edge has advanced with the announcement of its first reference designs.

In March, eight leading service providers within the ONF - AT&T, Comcast, China Unicom, Deutsche Telekom, Google, NTT Group, Telefonica and Turk Telekom - published their strategic plan whereby they would take a hands-on approach to the design of their networks after becoming frustrated with what they perceived as foot-dragging by the systems vendors.  

Timon SloaneThree months on, the service providers have initial drafts of the the first four reference designs: a broadband access architecture, a spine-leaf switch for network functions virtualisation (NFV), a more general networking fabric that uses the P4 packet forwarding programming language, and the open disaggregated transport network (ODTN).  

The ONF also announced four system vendors - Adtran, Dell EMC, Edgecore Networks, and Juniper Networks - have joined to work with the operators on the reference design programmes.

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Optical module trends: A conversation with Finisar

Finisar demonstrated recently a raft of new products that address emerging optical module developments. These include: 

• A compact coherent integrated tunable transmitter and receiver assembly 
• 400GBASE-FR8 and -LR8 QSFP-DD pluggable modules and a QSFP-DD active optical cable 
• A QSFP28 100-gigabit serial FR interface 
• 50-gigabit SFP56 SR and LR modules

Rafik Ward, Finisar’s general manager of optical interconnects, explains the technologies and their uses.

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Juniper bolsters its MX routers with packet processing ASIC

Juniper Networks has developed its next-generation packet processor, a single-chip package that includes 3D-stacked high-bandwidth memory. The device’s first use will be to enhance three of Juniper’s flagship MX series edge routers. 

The company has also announced software for the 5G cellular standard that separates the control and user planes, known as CUPS, and two new MX-series platforms that will use the company’s universal chassis.

The company’s MX series edge routers were first introduced in 2007. “The MX is a platform that is at the heart of our service provider customers globally, as well as a number of our cloud provider and enterprise customers,” says Sally Bament, Juniper’s vice president of service provider marketing (pictured).       

The latest enhancements will provide the MX edge router customers with another decade of support to meet their evolving service requirements, says Bament.

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The key elements of NFV usage: A guide

Orchestration, service assurance, service fulfilment, automation and closed-loop automation. These are important concepts associated with network functions virtualisation (NFV) technology being adopted by telecom operators as they transition their networks to become software-driven and cloud-based. 

Prayson Pate (pictured), CTO of the Ensemble division at ADVA Optical Networking, explains the technologies and their role and gives each a status update. 

Orchestration

Network functions virtualisation (NFV) is based on the idea of replacing physical appliances - telecom boxes - with software running on servers performing the same networking role.

Using NFV speeds up service development and deployment while reducing equipment and operational costs.

It also allows operators to work with multiple vendors rather than be dependent on a single vendor providing the platform and associated custom software.

Operators want to adopt software-based virtual network functions (VNFs) running on standard servers, storage and networking, referred to as NFV infrastructure (NFVI). 

In such an NFV world, the term orchestration refers to the control and management of virtualised services, composed of virtual network functions and executed on the NFV infrastructure.

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400ZR will signal coherent’s entry into the datacom world

• 400ZR will have a reach of 80km and a target power consumption of 15W 
• The coherent interface will be available as a pluggable module that will link data-centre switches across sites    
• Huawei expects first modules to be available in the first half of 2020
• At OFC, Huawei announced its own 250km 400-gigabit single-wavelength coherent solution that is already being shipped to customers

Coherent optics will finally cross over into datacom with the advent of the 400ZR interface.  So claims Maxim Kuschnerov, senior R&D manager at Huawei.

Maxim Kuschnerov400ZR is an interoperable 400-gigabit single-wavelength coherent interface being developed by the Optical Internetworking Forum (OIF) {add link}.

The 400ZR will be available as a pluggable module and as on-board optics using the COBO specification {add link}. The IEEE is also considering a proposal to adopt the 400ZR specification, initially for the data-centre interconnect market. “Once coherent moves from the OIF to the IEEE, its impact in the marketplace will be multiplied,” says Kuschnerov. 

But developing a 400ZR pluggable represents a significant challenge for the industry. “Such interoperable coherent 16-QAM modules won’t happen easily,” says Kuschnerov. “Just look at the efforts of the industry to have PAM-4 interoperability, it is a tremendous step up from on-off keying.” 

Despite the challenges, 400ZR products are expected by the first half of 2020.

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Oclaro uses Acacia’s Meru DSP for its CFP2-DCO

Oclaro will use Acacia Communications’ coherent DSP for its pluggable CFP2 Digital Coherent Optics (CFP2-DCO) module. The module will be compatible with Acacia’s own CFP2-DCO, effectively offering customers a second source. 

Tom Williams This is the first time Acacia is making its coherent DSP technology available to a fellow module maker, says Tom Williams, Acacia’s senior director, marketing.

Acacia benefits from the deal by expanding the market for its technology, while Oclaro gains access to a leading low-power coherent DSP, the Meru, and can bring to market its own CFP2-DCO product. 

Williams says the move was encouraged by customers and that having a second source and achieving interoperability will drive CFP2-DCO market adoption. That said, Acacia is not looking for further module partners. “With two strong suppliers, we don’t see a need to add additional ones,” says Williams.  

“This agreement is a sign that the market is reaching maturity, with suppliers transitioning from grabbing market share at all costs to more rational strategies,” says Vladimir Kozlov, CEO and founder of LightCounting Market Research.

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