The CDFP 400 Gig module
- The CDFP will be a 400 Gig short reach module
- Module will enable 4 Terabit line cards
- Specification will be completed in the next year
A CDFP pluggable multi-source agreement (MSA) has been created to develop a 400 Gigabit module for use in the data centre. "It is a pluggable interface, very similar to the QSFP and CXP [modules]," says Scott Sommers, group product manager at Molex, one of the CDFP MSA members.
Scott Sommers, MolexThe CDFP name stands for 400 (CD in Roman numerals) Form factor Pluggable. The MSA will define the module's mechanical properties and its medium dependent interface (MDI) linking the module to the physical medium. The CDFP will support passive and active copper cable, active optical cable and multi-mode fibre.
"The [MSA member] companies realised the need for a low cost, high density 400 Gig solution and they wanted to get that solution out near term," says Sommers. Avago Technologies, Brocade Communications Systems, IBM, JDSU, Juniper Networks, TE Connectivity along with Molex are the founding members of the MSA.
Specification
Samples of the 400 Gig MSA form factor have already been shown at the ECOC 2013 exhibition held in September 2013, as were some mock active optical cable plugs.
"The width of the receptacle - the width of the active optical cable that plugs into it - is slightly larger than a QSFP, and about the same width as the CFP4," says Sommers. This places the width of the CDFP at around 22mm. The CDFP however will use 16, 25 Gigabit electrical lanes instead of the CFP4's four.
"We anticipate a pitch-to-pitch such that we could get 11 [pluggables] on one side of a printed circuit board, and there is nothing to prohibit someone doing belly-to-belly," says Sommers. Belly-to-belly refers to a double-mount PCB design; modules mounted double sidedly. Here, 22 CDFPs would achieve a capacity of 8.8 Terabits.
The MSA group has yet to detail the full dimensions of the form factor nor has it specified the power consumption the form factor will accommodate. "The target applications are switch-to-switch connections so we are not targeting the long reach market that require bigger, hotter modules," says Sommers. This suggests a form factor for distances up to 100m and maybe several hundred meters.
The MSA members are working on a single module design and there is no suggestion of future additional CDFP form factors as this stage.
"The aim is to get this [MSA draft specification] out soon, so that people can take this work and expand upon it, maybe at the IEEE or Infiniband," says Sommers. "Within a year, this specification will be out and in the public domain."
Meanwhile, companies are already active on designs using these building blocks. "In a complex MSA like this, there are pieces such as silicon and connectors that all have to work together," says Sommers.
ECOC 2013 review - Part 2
- Oclaro's Raman and hybrid amplifier platform for new networks
- MxN wavelength-selective switch from JDSU
- 200 Gigabit multi-vendor coherent demonstration
- Tunable SFP+ designs proliferate
- Finisar extends 40 Gigabit QSFP+ to 40km
- Oclaro’s tackles wireless backhaul with 2km SFP+ module
Finisar's 40km 40 Gig QSFP+ demo. Source: Finisar
Amplifier market heats up
Oclaro detailed its high performance Raman and hybrid Raman/ Erbium-doped fibre amplifier platform. "The need for this platform is the high-capacity, high channel rates being installed [by operators] and the desire to be scalable - to support 400 Gig and Terabit super-channels in future," says Per Hansen, vice president of product marketing, optical networks solutions at Oclaro.
"Amplifiers are 'hot' again," says Daryl Inniss, vice president and practice leader components at market research firm, Ovum. For the last decade, amplifier vendors have been tasked with reducing the cost of their amplifier designs. "Now there is a need for new solutions that are more expensive," says Inniss. "It is no longer just cost-cutting."
Amplifiers are used in the network backbone to boost the optical signal-to-noise ratio (OSNR). Raman amplification provides significant noise improvement but it is not power efficient so a Raman amplifier is nearly always matched with an Erbium one. "You can think of the Raman as often working as a pre-amp, and the Erbium-doped fibre as the booster stage of the hybrid amplifier," says Hansen. System houses have different amplifier approaches and how they connect them in the field, while others build them on one card, but Raman/ Erbium-doped fibre are almost always used in tandem, says Hansen.
Oclaro provides Raman units and hybrid units that combine Raman with Erbium-doped fibre. "We can deliver both as a super-module that vendors integrate on their line cards or we can build the whole line card for them" says Hansen.
The Raman amplifier market is way bigger than people have forecast
Since Raman launches a lot of pump power into the fibre, it is vital to have low-loss connections that avoid attenuating the gain. "Raman is a little more sensitive to the quality of the connections and the fibre," says Hansen. Oclaro offers scan diagnostic features that characterise the fibre and determine whether it is safe to turn up the amplification.
"It can analyse the fibre and depending on how much customers want us to do, we can take this to the point that it [the design] can tell you what fibre it is and optimise the pump situation for the fibre," says Hansen. In other cases, the system vendors adopt their own amplifier control.
Oclaro says it is in discussion with customers about implementations. "We are shipping the first products based on this platform," says Hansen.
"[The] Raman [amplifier market] is way bigger than people have forecast," says Inniss. This is due to operators building long distance networks that are scalable to higher data rates. "Coherent transmission is the focal point here, as coherent provides the mechanism to go long distance at high data rates," says Ovum analyst, Inniss.
Wavelength-selective switches
JDSU discussed its wavelength-selective switch (WSS) products at ECOC. The company has previously detailed its twin 1x20 port WSS, which has moved from development to volume production.
At ECOC, JDSU detailed its work on a twin MxN WSS design. "It is a WSS that instead of being a 1xN - 1x20 or a 1x9 - it is an MxN," says Brandon Collings, chief technology officer, communications and commercial optical products at JDSU. "So it has multiple input and output ports on both sides." Such a design is used for the add and drop multiplexer for colourless and directionless reconfigurable optical add/ drop multiplexers (ROADMs).
"People have been able to build colourless and directionless architectures using conventional 1xN WSSes," says Collings. The MxN serves the same functionality but in a single integrated unit, halving the volume and cost for colourless and directionless compared to the current approach.
JDSU says it is also completing the development of a twin multicast switch, the add and drop multiplexer suited to colourless, directionless and contentionless ROADM designs.
200 Gigabit coherent demonstration
ClariPhy Communications, working with NeoPhotonics, Fujitsu Optical Components, u2t Photonics and Inphi, showcased a reference-design demonstration of 200 Gig coherent optical transmission using 16 quadrature amplitude modulation (16-QAM).
For the demonstration, ClariPhy provided the coherent silicon: the digital-to-analogue converter for transmission and the receiver analogue-to digital and digital signal processing (DSP) used to counter channel transmission impairments. NeoPhotonics provided the lasers, for transmission and at the receiver, u2t Photonics supplied the integrated coherent receiver, Fujistu Optical Components the lithium niobate nested modulator while Inphi provided the quad-modulator driver IC.
ClariPhy is developing a 28nm CMOS Lightspeed chip suited for metro and long-haul coherent transmission. The chip will support 100 and 200 Gigabit-per-second (Gbps) data rates and have an adjustable power consumption tailored to the application. The chip will also be suited for use within a coherent CFP module.
"All the components that we are talking about for 100 Gig are either ready or will soon be ready for 200 and 400 Gig," says Ferris Lipscomb, vice president of marketing at NeoPhotonics. To achieve 400Gbps, two 16-QAM channels can be used.
The DWDM market for 10 Gig is now starting to plateau
Tunable SFPs
JDSU first released a 10Gbps SFP+ optical module tunable across the C-band in 2012, a design that dissipates up to 2W. The SFP+ MSA agreement, however, calls for no greater than a 1.5W power consumption. "Our customers had to deal with that higher power dissipation which, in a lot of cases, was doable," says JDSU Collings.
Robert Blum, Oclaro
JDSU's latest tunable SFP+ design now meets the 1.5W power specification. "This gets into the MSA standard's power dissipation envelop and can now go into every SFP+ socket that is deployed," says Collings. To achieve the power target involved a redesign of the tunable laser. The tunable SFP+ is now sampling and will be generally available one or two quarters hence.
Oclaro and Finisar also unveiled tunable SFP+ modules at ECOC 2013. "The design is using the integrated tunable laser and Mach-Zehnder modulator, all on the same chip," says Robert Blum, director of product marketing for Oclaro's photonic components.
Neither Oclaro nor Finisar detailed their SFP+'s power consumption. "The 1.5W is the standard people are trying to achieve and we are quite close to that," says Blum.
Both Oclaro's and Finisar's tunable SFP+ designs are sampling now.
Reducing a 10Gbps tunable transceiver to a SFP+ in effect is the end destination on the module roadmap. "The DWDM market for 10 Gig is now starting to plateau," says Rafik Ward, vice president of marketing at Finisar. "From an industry perspective, you will see more and more effort on higher data rates in future."
40G QSFP+ with a 40km reach
Finisar demonstrated a 40Gbps QSFP+ with a reach of 40km. "The QSFP has embedded itself as the form-factor of choice at 40 Gig," says Ward.
Until now there has been the 850nm 40GBASE-SR4 with a 100m reach and the 1310nm 40GBASE-LR4 at 10km. To achieve a 40km QSFP+, Finisar is using four uncooled distributed feedback (DFB) lasers and an avalanche photo-detector (APD) operating using coarse WDM (CWDM) wavelengths spaced around 1310nm. The QSFP+ is being used on client side cards for enterprise and telecom equipment, says Finisar.
Module for wireless backhaul
Oclaro announced an SFP+ that supports the wireless Common Public Radio Interface (CPRI) and Open Base Station Architecture Initiative (OBSAI) standards used to link equipment in a wireless cell's tower and the base station controller.
Until now, optical modules for CPRI have been the 10km 10GBASE-LR4 modules. "You have a relatively expensive device for the last mile which is the most cost sensitive [part of the network]," says Oclaro's Hansen.
Oclaro's 1W SFP+ reduces module cost by using a simpler Fabry-Perot laser but at the expense of a 2km reach only. However, this is sufficient for a majority of requirements, says Hansen. The SFP supports 2.5G, 3Gbps, 6Gbps and 10Gbps rates. "CPRI has been used mostly at 3 Gig and 6 Gig but there is interest in 10 Gig due to growing mobile data traffic and the adoption of LTE," says Hansen.
The SFP+ module is sampling and will be in volume production by year end.
For Part 1, click here
ECOC 2013 review - Part 1
Gazettabyte surveys some of the notable product announcements made at the recent European Conference on Optical Communication (ECOC) held in London.
Part 1: Highlights
- First CFP4 module demonstration from Finisar
- Acacia Communications unveils first 100 Gig coherent CFP
- Oplink announces a 100 Gig direct detection CFP
- Second-generation coherent components take shape
100 Gigabit pluggables
Finisar used the ECOC exhibition to demonstrate the first CFP4 optical module, the smallest of the CFP MSA family of modules. The first CFP4 supports the 100GBASE-SR4 standard comprising four electrical and four optical channels, each at 25 Gigabit-per-second (Gbps).
The CFP4 is a quarter of the width of the CFP while the CFP2 is about a half the CFP's width. The CFP4 thus promises to quadruple the faceplate port density compared to using the CFP. Finisar says the CFP4 does even better, supporting line cards with 3.6 Terabits of capacity.
"It is not just the [CFP4's] width but the length and height that are shorter," says Rafik Ward, vice president of marketing at Finisar. The CFP4s can be aligned in two columns - belly-to-belly - on the card, achieving 3.6Tbps, each row comprising 18 CFP4 modules.
We see the CFP4 as a necessity to continue to grow the 100 Gigabit Ethernet market
The CFP4 was always scheduled to follow quickly the launch of the CFP2, says Ward. But the availability of the CFP4 will be important for the MSA. Data centre switch vendor Arista Networks has said that the CFP2 was late to market, while Cisco Systems has developed the CPAK, its own CFP2 alternative. "We see it [the CFP4] as a necessity to continue to grow the 100 Gigabit Ethernet market," says Ward.
Other 100 Gigabit Ethernet (GbE) variants will follow in the CFP4 form factor such as the LR4 and SR10 and the 10x10GbE breakout variant. This raises the interesting prospect of requiring an “inverse gearbox” chip that will translate between the CFP4's four electrical channels and the SR10's 10 optical channels. "We are going to see a lot of design activity around CFP4 in 2014," says Ward.
Meanwhile, Acacia Communications unveiled the AC-100, the first 100 Gig coherent CFP module for metro and regional networks, that includes a digital signal processor (DSP) system-on-chip.
"The DSP can be programmed for different performance and power levels to achieve a range of distances," says Daryl Inniss, vice president and practice leader components at market research firm, Ovum.
Acacia Communications says a CFP-based coherent design provides carriers and content providers with a 100 Gig metro solution that is more economical than 10 Gig.
Oplink Communications announced a direct detection 100 Gig metro CFP at ECOC. The 4x28Gbps CFP uses MultiPhy's maximum likelihood sequence estimation (MLSE) algorithm implemented using its MP1100Q and MP1101Q ICs. The devices enhance the reach of the module and allows 10 Gig optical components to be used for the receive and transmit paths. "Oplink’s CFP is the first module to come to market with our devices inside," says Neal Neslusan, vice president of marketing and sales at MultiPhy.
There are now at least three vendors selling direct-detection 100Gbps modules, says Neslusan, with Oplink and Menara Networks, which has also announced a CFP product, joining Finisar.
MultiPhy is working with several additional companies and that one system vendor will come to market with a product using the company's chips in the coming months. The company is also working on a second-generation direct detection IC design. "We believe there is a compelling roadmap story for direct detection," says Neslusan.
Oclaro announced it is now shipping in volume its 10km 100GBASE-LR4 CFP2 supporting 100GbE and OTU4 (OTN) rates. Oclaro has demonstrated the CFP2 working with a Xilinx Virtex 7 FPGA. "If customers choose that combination of technology, we have already tested it for them and they can rely on those rates [100GbE and OTU4] working," says Per Hansen, vice president of product marketing, optical networks solutions at Oclaro.
JDSU also said that its CFP2 LR4 is nearing completion. "We are getting pretty close to releasing it," says Brandon Collings, chief technology officer, communications and commercial optical products at JDSU.
Ed Murphy, JDSU
The integrated transmit and receive optical sub-assembly (TOSA/ ROSA) designs for the CFP2 LR4 use hybrid integration.
"In this case it is not monolithic integration as it is in the case of the indium phosphide line side modules but hybrid integration taking advantage of our PLC (planar lightwave circuit) technology in combination with arrays of photo detectors or high speed EMLs (externally modulated lasers)," says Murphy.
JDSU has based its module roadmap on the CFP2 TOSA and ROSA designs. The designs are sufficiently integrated to also fit within the QSFP28 and CFP4 modules.
There may be tweaks to the chips to lower the power dissipation, says Murphy, but these will be minor variants on existing parts.
Coherent components
Several component makers discussed their latest compact designs for next-generation coherent transmission line cards and modules.
NeoPhotonics detailed its micro-ITLA narrow linewidth tunable laser (micro-ITLA) that occupies less than a third of the area of the existing ITLA design. The company also announced a small form factor intradyne coherent receiver (SFF-ICR), less than half the size of existing integrated coherent receivers (ICRs).
NeoPhotonics supplies components to module and system vendors, and says customer interest in the second-generation coherent components is for higher port count line cards. "Instead of 100 Gig on a line card, you can have 200 or 400 Gigabit on a line card," says Ferris Lipscomb, vice president of marketing at NeoPhotonics. Moving to pluggable module designs will be a follow-on development, but for now, the market is not quite ready, he says.
An integrated coherent transmitter for metro, combining a tunable laser and integrated indium phosphide modulator in a compact package is also offered by NeoPhotonics.
The laser has two outputs - one output is modulated for the transmission while the second output is a local oscillator source feeding the coherent receiver. About half of all 100Gbps designs use such a split laser source, says Lipscomb, rather than two separate lasers, one each for the transmitter and the receiver. "That means that one transponder can only transmit and receive the same wavelength and is a little less flexible but for cost reduction that is what people are doing," says Lipscomb.
Oclaro is now sampling to customers its next-generation indium phosphide-based coherent components. The company, also a supplier of coherent modules, says the components will enable CFP and CFP2 pluggable coherent transceivers. The pluggable modules are suited for use in metro and metro regional networks.
Oclaro's components include an integrated transmitter comprising an indium phosphide laser and modulator, and the SFF-ICR. Oclaro's micro-ITLA is in volume production and has an output power high enough to perform both the transmit and the local oscillator functions. The micro-ITLA is used for line cards, 5x7-inch and 4x5-inch MSAs module and CFP designs.
u2t Photonics is another company that is developing a SFF-ICR. The company gave a private demonstration at ECOC to its customers of its indium phosphide modulator for use with CFP and CFP2 modules. "We demonstrated technical feasibility; it is a prototype which shows the capability of indium phosphide technology," says Jens Fiedler, executive vice president sales and marketing at u2t Photonics.
u2t Photonics and Finisar both licensed 100Gbps coherent indium phosphide modulator technology developed at the Fraunhofer Heinrich-Hertz-Institute.
There are new coherent DSP chips coming out early next year
Also showcased was u2t's gallium arsenide modulator technology implementing 16-QAM (quadrature amplitude modulation) at ECOC, but the company has yet to announce a product.
JDSU also gave an update on its line side coherent components. It is developing an integrated transmitter - a laser with nested modulators - for coherent applications. "This work is underway as a technology for line side CFP and CFP2 modules," says Ed Murphy, senior director, communications and commercial optical products at JDSU.
The difference between the CFP and CFP2 coherent modules is that the DSP system-on-chip is integrated within the CFP. Acacia's AC-100 CFP is the first example of such a product. For the smaller CFP2, the DSP will reside on the line card.
"There are new DSP [chips] coming out early next year," says Robert Blum, director of product marketing for Oclaro's photonic components. The DSPs will require a power consumption no greater than 20W if the complete design - the DSP and optics - is to comply with the CFP's maximum power rating of 32W.
Pluggable coherent modules promise greater port densities per line card. The modules can also be deployed with traffic demand and, in the case of a fault, can be individually swapped rather than having to replace the line card, says Blum.
JDSU says two factors are driving the metro coherent market. One is the need for lower cost designs to meet metro's cost-sensitive requirements. The second is that the metro distances can use essentially the same devices for 16-QAM to support 200Gbps links as well as 100Gbps. "It is the same modulator structure; maybe a few of the specs are a bit tighter but you can think of it as the same device," says Murphy.
System vendors have trialled 200Gbps links but deployments are expected to start from 2014. The deployments will likely use lithium niobate modulators, says Murphy, but will be followed quickly by indium phosphide designs.
NeoPhotonics used ECOC to declare that it has now integrated the semiconductor optical component arm of Lapis Semiconductor which it acquired for $35.2 million in March 2013.
Ferris Lipscomb
The unit, known as NeoPhotonics Semiconductor GK, makes drivers and externally modulated lasers. "These are key technologies for high-speed 100 Gig and 400 Gig transmissions, both on the line side and on the client side," says Lipscomb.
NeoPhotonics, previously a customer of Lapis, decided to acquire the unit and benefit from vertical integration as it expands its 100 Gig and higher-speed coherent portfolio.
Owning the technology has cost and optical performance benefits, says Lipscomb. It enables the integration of a design on one chip, thereby avoiding interfacing issues.
Further reading:
Part 2, click here
OIF demonstrates its 25 Gig interfaces are ready for use
The Open Internetworking Forum (OIF) has demonstrated its specified 25 and 28 Gigabit-per-second (Gbps) electrical interfaces working across various vendors' 100 Gigabit modules and ICs.
"The infrastructure over the backplane is maturing to the point of 25 Gig; you don't need special optical backplanes" John Monson, Mosys
"The ecosystem is maturing," says John Monson, vice president of marketing at Mosys, one of the 11 firms participating in the demonstrations. "The demos are not just showing the electrical OIF interfaces but their functioning between multiple vendors, with optical standards running across them at 100 Gig."
The demonstrations - using the CFP2, QSFP and CPAK optical modules and the 28Gbps CEI-28G-VSR module-to-chip electrical interface - set the stage for higher density 400 and 800 Gigabit line cards, says Monson. The CEI-28G-VSR is specified for up to 10dB of signal loss, equating to some 4 to 6 inches of trace on a high-quality material printed circuit board.
Higher density system backplanes are also ready using the OIF's CEI-25G-LR interface. "Until I get backplanes capable of high rates, there are just too many pins at 10 Gig to support 800 Gig and Terabit [line card] solutions," says Monson.
The ECOC demonstrations include two 100Gbps modules linked over fibre. "You have two CFP2 modules, from different vendors, running at 4x28Gbps OTN [Optical Transport Network] rates over 10km," says Monson.
On the host side, the CEI-28G-VSR interface sits between a retimer inside the CFP2 module and a gearbox chip that translates between 25Gbps and the 10Gbps lanes that link a framer or a MAC IC on the line card.
The demonstrations cover different vendors' gearbox ICs talking to different optical module makers' CFP2s as well as Cisco's CPAK. "We are mixing and matching quite a bit in these demos," says Monson.
The OIF has already started work for the next-generation electrical interfaces that follow the 25 and 28 Gigabit ones
There is also a demo of a QSFP+ module driving active copper cable and one involving two 100 Gigabit SR10 modules and a gearbox IC. Three further demos involve the CEI-25G-LR backplane interface. Lastly, there is a demo involving the thermal modelling of a line card hosting eight slots of the CDFP 400Gbps optical module MSA.
The OIF's CEI-25G-LR is specificed for up to 25dB of loss. The IEEE P802.3bj 100 Gbps Backplane and Copper Cable Task Force is specifying an enhanced backplane electrical interface that supports 35dB of loss using techniques such as forward error correction.
"What the demos say is that the electrical interfaces, at 25 Gig, can be used not just for a 4-6 inch trace, but also high-density backplanes," says Monson. As a result line card density will increase using the smaller form factor 100Gbps optical modules. It also sets the stage for 400 Gig individual optics, says Monson: "The infrastructure over the backplane is maturing to the point of 25 Gig; you don't need special optical backplanes."
Meanwhile, standards work for 400 Gigabit Ethernet is still at an early stage, but proposals for 56Gbps links have been submitted for consideration. "Such a rate would double capacity and reduce the number of pins required on the ASSPs and ASICs," says Monson.
As to how the electrical interface for 400 Gigabit Ethernet will be implemented, it could be 16x25Gbps or 8x50Gbps lanes and will also be influenced by the chosen optical implementation. The OIF has already started work for the next-generation electrical interfaces that follow the 25 and 28 Gigabit ones.
The 11 companies and the two test and measurement companies taking part, as well as the demonstrations, are detailed in an OIF White Paper, click here.