OIF adds a short-reach design to its 1600ZR/ ZR+ portfolio

The OIF (Optical Internetworking Forum) has broadened its 1600-gigabit coherent optics specification work to include a third project, complementing the 1600ZR and 1600ZR+ initiatives.

Karl Gass

The latest project will add a short-reach 'coherent-lite' digital design to deliver a reach of 2km to 20km and possibly 40km with a low latency below 300ns.

The low latency will suit workloads and computing resources distributed across data centres.

"The coherent-lite is more than just the LR (long reach) work that we have done [at 400 gigabits and 800 gigabits]," says Karl Gass, optical vice chair of the OIF's physical link layer (PLL) working group, adding that the 1600-gigabit coherent-lite will be a distinct digital design.

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The compound complexity of co-packaged optics

Part 1: The OIF’s co-packaging initiative

Large-scale data centres consume huge amounts of power; one building on a data centre campus can consume 100MW. But there is a limit as to the overall power that can be supplied.

Jeff Hutchins

The challenge facing data centre operators is that networking, used to link the equipment inside the data centre, continues to consume more and more power.

That means less power remains for the servers; the compute that does the revenue-generating work.

This is forcing a rethink regarding networking and explains the growing interest in co-packaged optics, a technique that effectively adds optical input-output (I/O) to a chip.

Two industry organisations - the OIF and The Consortium for On-Board Optics (COBO) - have each started work to identify the requirements needed for co-packaged optics adoption.

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Telecoms embraces 400ZR optics for IP-over-DWDM

Verizon Media has trialled 400-gigabit coherent pluggable optics to improve the delivery of video content to subscribers.

Tomas Maj

Verizon Media added a 400ZR QSFP-DD module from Inphi to a switch already using 100-gigabit optics to upgrade its content delivery network.

Adding dense wavelength-division multiplexing (DWDM) optics to a switch enables it to send IP traffic (IP-over-DWDM) directly without needing a separate DWDM data centre interconnect box and additional client-side optics to link the two platforms (see diagram).

“Verizon Media, showing leadership outside the hyperscalers, is moving to IP-over-DWDM,” says Tomas Maj, senior director, marketing, optical interconnect at Inphi. “It shows the maturity of the ecosystem and the confidence of more and more operators in IP-over-DWDM and 400ZR.”

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Acacia targets access networks with coherent QSFP-DD

• Acacia Communications has announced a 100-gigabit coherent QSFP-DD pluggable module.
• The module is the first of several for aggregation in the access network.

The second article addressing what next for coherent

Part 2: 100-gigabit coherent QSFP-DD

Acacia Communications has revisited 100-gigabit coherent but this time for access rather than metro networks.

Acacia’s metro 100-gigabit coherent pluggable product, a CFP, was launched in 2014. The pluggable has a reach from 80km to 1,200km and consumes 24-26W.

Tom Williams

The latest coherent module is the first QSFP-DD to support a speed lower than the 400-gigabit 400ZR and ZR+ applications that have spurred the coherent pluggable market. 

The launching of a 100-gigabit coherent QSFP-DD reflects a growing need to aggregate 10 Gigabit Ethernet (GbE) links at the network edge as 5G and fibre are deployed.

“The 10GbE links in all the different types of access networks highlight a need for a cost-effective way to do this aggregation,” says Tom Williams, vice president of marketing at Acacia.

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Open Eye MSA gets webscale attention

Microsoft has trialled optical modules that use signalling technology developed by the Open Eye Consortium.

The webscale player says optical modules using the Open Eye’s analogue 4-level pulse-amplitude modulation (PAM-4) technology consume less power than modules with a PAM-4 digital signal processor (DSP).

“Open Eye has shown us at least an ability that we can do better on power,” says Brad Booth, director, next cloud system architecture, Azure hardware systems and infrastructure at Microsoft, during an Open Eye webinar.

Brad BoothOptical module power consumption is a key element of the total power budget of data centres that can have as many as 100,000 servers and 50,000 switches.

“You want to avoid running past your limit because then you have to build another data centre,” says Booth.

But challenges remain before Open Eye becomes a mainstream technology, says Dale Murray, principal analyst at market research firm, LightCounting.

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The era of 400G coherent pluggables finally emerges

Part 1: 7nm coherent DSPs, ZR and ZR+

The era of 400-gigabit coherent pluggable modules has moved a step closer with Inphi’s announcement of its Canopus coherent digital signal processor (DSP) and its QSFP-DD ColorZ II optical module. 

NeoPhotonics has also entered the fray, delivering first samples of its 400-gigabit ClearLight CFP2-DCO module that uses the Canopus DSP.

Pranay AiyaThe ColorZ II and ClearLight modules support the 400ZR OIF standard used to link data centres up to 120km apart. They also support extended modes, known as ZR+, that is not standardised.

ZR+’s modes include 400 Gigabit-per-second (Gbps) over distances greater than 400ZR's 120km and lower data rates over metro-regional and long-haul distances.    

The announcements of the Canopus DSP and 400-gigabit pluggable coherent modules highlight the approaches being taken for ZR+. Optical module vendors are aligning around particular merchant DSPs such that interoperability exists but only within each camp.  

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Companies gear up to make 800 Gig modules a reality

Nine companies have established a multi-source agreement (MSA) to develop optical specifications for 800-gigabit pluggable modules.

Maxim Kuschnerov

The MSA has been created to address the continual demand for more networking capacity in the data centre, a need that is doubling roughly every two years. The largest switch chips deployed have a 12.8 terabit-per-second (Tbps) switching capacity while 25.6-terabit and 51-terabit devices are in development. 

“The MSA members believe that for 25.6Tbps and 51.2Tbps switching silicon, 800-gigabit interconnects are required to deliver the required footprint and density,” says Maxim Kuschnerov, a spokesperson for the 800G Pluggable MSA.

A 1-rack-unit (1RU) 25.6-terabit switch platform will use 32 such 800-gigabit modules while a 51.2-terabit 2RU platform will require 64.

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