Teraxion embraces silicon photonics for its products
Teraxion has become a silicon photonics player with the launch of its compact 40 and 100 Gigabit coherent receivers.
The Canadian optical component company has long been known for its fibre Bragg gratings and tunable dispersion compensation products. But for the last three years it has been developing expertise in silicon photonics and at the recent European Conference on Optical Communications (ECOC) exhibition it announced its first products based on the technology.
"You don't have this [fabless] model for indium phosphide or silica, while an ecosystem is developing around silicon photonics"
Martin Guy, Teraxion
"We are playing mainly in the telecom business, which accounts for 80% of our revenues," says Martin Guy, vice president, product management & technology at Teraxion. "It is clear that our customers are going to more integration and smaller form-factors so we need to follow our customers' requirements."
Teraxion assessed several technologies but chose silicon photonics and the fabless model it supports. "We are using all our optical expertise that we can apply to this material but use a process already developed for the CMOS industry, with the [silicon] wafer made externally," says Guy. "You don't have this [fabless] model for indium phosphide or silica, while an ecosystem is developing around silicon photonics."
The company uses hybrid integration for its coherent receiver products, with silicon implementing the passive optical functions to which the active components are coupled. Teraxion is using externally-supplied photo-detectors which are flip-chipped onto the silicon for its coherent receiver.
"We need to use the best material for the function for this high-end product," says Guy. "Our initial goal is not to have everything integrated in silicon."
Coherent receiver
A coherent receiver comprises two inputs - the received optical signal and the local oscillator - and four balanced receiver outputs. Also included in the design are two polarisation beam splitters and two 90-degree hybrid mixers.
Several companies have launched coherent receiver products. These include CyOpyics, Enablence, NEL, NeoPhotonics, Oclaro and u2t Photonics. Silicon photonics player Kotura has also developed the optical functions for a coherent receiver but has not launched a product.
One benefit of using silicon photonics, says Teraxion, is the compact optical designs it enables.
The Optical Internetworking Forum (OIF) has specified a form factor for the 100 Gigabit-per-second (Gbps) coherent receiver. Teraxion has developed a silicon photonics-based product that matches the OIF's form factor sized 40mmx32mm. This is for technology evaluation purposes rather than a commercial product. "If customers want to evaluate our technology, they need to have a compatible footprint with their design," explains Guy. This is available in prototype form and Teraxion has customers ready to evaluate the product.
Teraxion will come to market with a second 100 Gigabit coherent receiver design that is a third of the size of the OIF's form factor, measuring 23mmx18mm (0.32x the area of the OIF specification). The compact coherent receivers for 40 and 100Gbps will be available in sample form in the first quarter of 2013.
Teraxion's OIF-specification 100 Gig coherent receiver (left) for test purposes and its compact coherent receiver product. Source: Teraxion
"We match the OIF's performance with this design but there are also other key requirements from customers that are not necessarily in the OIF specification," says Guy.
The compact 100Gbps design is of interest to optical module and system vendors but there is no one view in terms of requirements or the desired line-side form-factor that follows the 5x7-inch MSA. Indeed there are some that are interested in developing a 100 Gigabit CFP module for metro applications, says Guy.
Roadmap
Teraxion's roadmap includes further integration of the coherent receiver's design. "We are using hybrid integration but eventually we will look at having the photo-detectors integrated within the material,” says Guy.
The small size of the coherent design means there is scope for additional functionality to be included. Teraxion says that customers are interested in integrating variable optical attenuators (VOAs). The local oscillator is another optical function that can be integrated within the coherent receiver.
In 2005 Teraxion acquired Dicos Technologies, a narrow line-width laser specialist. Teraxion's tunable narrow line-width laser product - a few kiloHertz wide - is available in the lab. "The purpose of this product is not to be deployed on the line card - right now," says Guy. "We believe this type of performance will be required for next-generation 100 Gig, 400 Gig, 1 Terabit coherent communication systems where you will need a very 'clean' local oscillator."
Teraxion is also working on developing a silicon-photonics-based modulator. The company has been exploring integrating Bragg gratings within silicon waveguides for which it has applied for patents. This is several years out, says Guy, but has the potential to enable high-speed modulators suited for short-reach datacom applications.
AppliedMicro samples 100Gbps CMOS multiplexer
AppliedMicro has announced the first CMOS merchant multiplexer chip for 100Gbps coherent optical transmission. The S28032 device supports dual polarisation, quadrature phase-shift keying (DP-QPSK) and has a power consumption of 4W, half that of current multiplexer chip designs implemented in BiCMOS.
The S28032 100 Gig multiplexer IC. Source: AppliedMicro
"CMOS has a very low gain-bandwidth product, typically 100GHz," says Tim Warland, product marketing manager, connectivity solutions at AppliedMicro. “Running at 32GHz, we have been able to achieve a very high bandwidth with CMOS."
Significance
The availability of a CMOS merchant device will be welcome news for optical transport suppliers and 100Gbps coherent module makers. CMOS has better economics than BiCMOS due to the larger silicon wafers used and the chip yields achieved. The reduced power consumption also promotes the move to smaller-sized optical modules than the current 5x7-inch multi-source agreement (MSA).
"By reducing the power and the size, we can get to a 4x6-inch next-generation module,” says Warland. “And perhaps if we go for a shorter [optical transmission] reach - 400-600km - we could get into a CFP; then you can get four modules on a card.”
"Coherent ultimately is the solution people want to go to [in the metro] but optical duo-binary will do just fine for now"
Tim Warland, AppliedMicro
Chip details
The S28032 has a CAUI interface: 10x12Gbps input lanes that are multiplexed into four lanes at 28Gbps to 32Gbps. The particular data rate depends on the forward error correction (FEC) scheme used. The four lanes are DQPSK-precoded before being fed to the polarisation multiplexer to create the DP-QPSK waveforms.
The device also supports the SFI-S interface - 21 input channels, each at 6Gbps. This is significant as it enables the S28032 to be interfaced to NTT Electronics' (NEL) DSP-ASIC coherent receiver chip that has been adopted by 100Gbps module makers Oclaro and Opnext (now merged) as well as system vendors including Fujitsu Optical Systems and NEC.
The mux IC within a 100Gbps coherent 5x7-inch optical module. Source: AppliedMicro
The AppliedMicro multiplexer IC, which is on the transmit path, interfaces with NEL's DSP-ASIC that is on the receiver path, because the FEC needs to be a closed loop to achieve the best efficiency, says Warland. "If you know what you are transmitting and receiving, you can improve the gain and modify the coherent receiver sampling points if you know what the transmit path looks like," he says.
The DSP-ASIC creates the transmission payloads and uses the S28032 to multiplex those into 28Gbps or greater speed signals.
The SFI-S interface is also suited to interface to FPGAs, for those system vendors that have their own custom FPGA-based FEC designs.
"Packet optical transport systems is more a potential growth engine as the OTN network evolves to become a real network like SONET used to be"
Francesco Caggioni. AppliedMicro
The multiplexer chip's particular lane rate is set by the strength of the FEC code used and its associated overhead. Using OTU4 frames with its 7% overhead FEC, the resulting data rate is 27.95Gbps. With a stronger 15% hard-decision FEC, each of the 4 channel's data rate is 30Gbps while it is 31.79Gbps with soft-decision FEC.
"It [the chip] has got sufficient headroom to accommodate everything that is available today and that we are considering in the OIF [Optical Internetworking Forum],” says Warland. The multiplexer is expected to be suitable for coherent designs that achieve a reach of up to 2,000-2,500km but the sweet spot is likely to be for metro networks with a reach of up to 1,000km, he says.
But while the CMOS device can achieve 32Gbps, it has its limitations. "For ultra long haul, we can't support a FEC rate higher than 20%," says Warland. "For that, a 25% to 30% FEC is needed."
AppliedMicro is sampling the device to lead customers and will start production in 1Q 2013.
What next
The S28032 joins AppliedMicro's existing S28010 IC suited for the 10km 100 Gigabit Ethernet 100GBASE-LR4 standard, and for optical duo-binary 100Gbps direct detection that has a reach of 200-1,000km.
"Our next step is to try and get a receiver to match this chip," says Warland. But it will be different to NEL's coherent receiver: "NEL's is long haul." Instead, AppliedMicro is eyeing the metro market where a smaller, less power-hungry chip is needed.
"Coherent ultimately is the solution people want to go to [in the metro] but optical duo-binary will do just fine for now," says Warland.
Two million 10Gbps OTN ports
AppliedMicro has also announced that it has shipped 2M 10Gbps OTN silicon ports. This comes 18 months after it announced that it had shipped its first million.
"OTN is showing similar growth to the 10 Gigabit Ethernet market but with a four-year lag," says Francesco Caggioni, strategic marketing director, connectivity solutions at AppliedMicro.
The company sees OTN growth in the IP edge router market and for transponder and muxponder designs, while packet optical transport systems (P-OTS) is an emerging market.
"Packet optical transport systems is more a potential growth engine as the OTN network evolves to become a real network like SONET used to be," says Caggioni. "We are seeing development but not a lot of deployment."
Further reading:
100 Gigabit 'unstoppable'
A Q&A with Andrew Schmitt (@aschmitt), directing analyst for optical at Infonetics Research.
"40Gbps has even less value in the metro than in the core"
Andrew Schmitt, Infonetics Research
A study from market research firm, Infonetics Research, has found that operators have a strong preference for deploying 100 Gigabit-per-second (Gbps) technology as they upgrade their networks.
Infonetics interviewed 21 incumbent service providers, competitive operators and mobile operators that have either 40Gbps, 100Gbps or both wavelength types installed in their networks, or that plan to install by next year (2013).
The operators surveyed, from all the major regions, account for over a quarter (28%) of worldwide telecom carrier revenue and capital expenditure.
The study's findings include:
- A strong preference by the carriers for 100Gbps transport in both Brownfield and Greenfield installations. Carriers will use 40 and 100Gbps to the same degree in existing Brownfield networks while favouring 100Gbps for new, Greenfield builds.
- The reasons to deploy 40Gbps and 100Gbps optical transport equipment include lowering the cost per bit, taking advantage of the superior dispersion performance of coherent optics, and lowering incremental common equipment costs due to the increased spectral efficiency.
- Most respondents indicate 40Gbps is only a short-term solution and will move the majority of installations to 100Gbps once those products become widely available.
- Non-coherent 100Gbps is not yet viewed as an important technology.
- Colourless and directionless ROADMs and Optical Transport Network (OTN) switching are important components of Greenfield builds; gridless and contentionless ROADMs are much less so.
Q&A with Andrew Schmitt
Q. A key finding is that 40Gbps and 100Gbps are equally favoured for Brownfield routes. And is it correct that Brownfield refers to existing routes carrying 10Gbps and maybe 40Gbps wavelengths while Greenfield involves new 100Gbps wavelengths? What is it about Brownfield that 40Gbps and 100Gbps have equal footing? Equally, for Greenfield, is the thinking: "If we are deploying a new lit fibre, we might as well start with the newest and fastest"?
A: The assumptions on Brownfield versus Greenfield are correct, the definitions in the survey and the report are more detailed but that is right.
It is more an issue that they [carriers] are building with 40Gbps now but will transition to 100Gbps where it can be used. Where it can't be used they stick with 40Gbps. There are many reasons why 100Gbps may not work in existing networks.
Q: Another finding is that 40Gbps is seen as a short-term solution. What is short term? And will that also be true for the metro or does metro have its own dynamic?
A: We didn't test timing explicitly for Greenfield versus Brownfield networks. It [40Gbps] doesn't necessarily peak, it is just not growing at the same rate as 100Gbps. And 40Gbps has even less value in the metro than in the core, particularly in Greenfield builds. With Greenfield 100Gbps combined with soft-decision forward error correction (SD-FEC), it is almost as good as 40Gbps.
Q: The study found that non-coherent 100Gbps isn't yet viewed as an important technology. Why do you think that is so? And what is your take on the non-coherent 100Gbps opportunity?
A: The jury is still out.
The large customers I spoke with haven't looked at it and therefore can't form an opinion. A lot of promises and marketing at this point but that doesn't mean it won't work. Module vendors are pretty excited about it and they aren't stupid.
Q: You say colourless and directionless is seen as important ROADM attributes, gridless and contentionless much less so. If operators are building 100Gbps Greenfield overlays, is not gridless a must to future-proof the network investment?
A: The gridless requirement is completely overblown and folks positioning it as a requirement today haven't done the work to understand the issues trying to use it today. This survey was even more negative than I expected.
The CFP4 optical module to enable Terabit blades
Source: Gazettabyte, Xilinx
The CFP2 is about half the size of the CFP while the CFP4 is half the size of the CFP2. The CFP4 is slightly wider and longer than the QSFP.
The two CFP modules will use a 4x25Gbps electrical interface, doing away with the need for a 10x10Gbps to 4x25Gbps gearbox IC used for current CFP 100GBASE-LR4 and -ER4 interfaces. The CFP2 and CFP4 are also defined for 40 Gigabit Ethernet use.
The CFP's maximum power rating is 32W, the CFP2 12W and the CFP4 5W. But vendors that put eight CFP2 or 16 CFP4s on a blade still want to meet the 60W total power budget.
Getting close: Four CFP modules deliver slightly less bandwidth than 48 SFP+ modules: 4x100Gbps versus 480Gbps. The four also consume more power - 60w versus 48W. Moving to the CFP2 module will double the blade's bandwidth without consuming more power while the CFP4 will do the same again. a blade with 16 CFP4 modules promises 1.6Tbps while requiring 60W. Source: Xilinx
The first CFP2 modules are expected this year - there could be vendor announcements as early as the upcoming OFC/NFOEC 2012 show to be held in LA in the first week in March. The first CFP4 products are expected in 2013.
Further reading
The CFP MSA presentation: CFP MSA 100G roadmap and applications
2012: The year of 100 Gigabit transponders
“The world is moving to coherent, there is no question about that”
Per Hansen, Oclaro
The 100Gbps module expands the company's coherent offerings. Oclaro is already shipping a 40Gbps coherent module. “The world is moving to coherent, there is no question about that,” says Per Hansen, vice president of product marketing, optical networks solutions at Oclaro.
Why is this significant?
Having a selection of 100Gbps long-haul optical modules will aid the uptake of high-capacity links in the network core. Opnext announced in September its OTM-100 100Gbps coherent optical module, in production from April 2012. And at least one other module maker has worked with ADVA Optical Networking to make its 100Gbps module, a non-coherent design.
The 100Gbps coherent optical modules will enable system vendors without their own technology to enter the marketplace. It also presents those system vendors with their own 100Gbps technology - the likes of Alcatel-Lucent, Ciena, Cisco and Huawei - with a dilemma: do they continue to evolve their products or embrace optical modules?
“These system vendors have developed [100Gbps] in-house to have a strategic differentiator," says Hansen. "But with lower volumes you have a higher cost.” The advent of 100Gbps modules diminishes the strategic advantage of in-house technology while enabling system vendors to benefit from cheaper, more broadly available modules, he says.
What has been done
Oclaro is still developing the MI 8000XM module and has yet to reveal the reach performance of the module: “We want to do many more tests before we share,” says Hansen. The module will meet the Optical Internetworking Forum's (OIF) 100Gbps module maximum power consumption limit of 80W, he says.
The OIF 100 Gigabit module architecture
The NEL DSP chip is the same device that Opnext is using for its 100Gbps module. “A partnership agreement and sourcing arrangement with NEL allows us to come to market with what we think is a very good product at the right time,” says Hansen.
The DSP uses soft-decision forward error correction. Opnext has said this adds 2-3dB to the optical performance to achieve a reach of 1500-1600km before regeneration.
In 2010 Oclaro announced it had invested US $7.5 million in Clariphy Communications as part of the chip company's development of its 100Gbps coherent receiver chip, the CL10010. As part of the agreement, Oclaro will get a degree of exclusivity as a module supplier (at least one other module maker will also benefit).
ClariPhy has said that while it will not be first to market with a 100Gbps ASIC, the CL10010 will be a 28nm CMOS second-generation chip design. To be able to enter the market with a 100Gbps module next year, Oclaro adopted NEL's design which exists now.
Next
Hansen says that the MI 8000XM, which uses a lithium niobate modulator, is designed to achieve maximum reach and optical performance. But future 100Gbps modules will be developed that may use other modulator technologies and be optimised in terms of power or size.
Hansen is also in no doubt that the next speed hike after 100Gbps will be 400Gbps. Like 100Gbps, there will be some early-adopter operators that embrace the technology one or two years before the consensus.
Such a development is still several years away, however, since an industry standard for 400Gbps must be developed which is only expected in 2014 only.
100 Gigabit: An operator view
Gazettabyte spoke with BT, Level 3 Communications and Verizon about their 100 Gigabit optical transmission plans and the challenges they see regarding the technology.
Briefing: 100 Gigabit
Part 1: Operators
Operators will use 100 Gigabit-per-second (Gbps) coherent technology for their next-generation core networks. For metro, operators favour coherent and have differing views regarding the alternative, 100Gbps direct-detection schemes. All the operators agree that the 100Gbps interfaces - line-side and client-side - must become cheaper before 100Gbps technology is more widely deployed.
"It is clear that you absolutely need 100 Gig in large parts of the network"
Steve Gringeri, Verizon
100 Gigabit status
Verizon is already deploying 100Gbps wavelengths in its European and US networks, and will complete its US nationwide 100Gbps backbone in the next two years.
"We are at the stage of building a new-generation network because our current network is quite full," says Steve Gringeri, a principal member of the technical staff at Verizon Business.
The operator first deployed 100Gbps coherent technology in late 2009, linking Paris and Frankfurt. Verizon's focus is on 100Gbps, having deployed a limited amount of 40Gbps technology. "We can also support 40 Gig coherent where it makes sense, based on traffic demands," says Gringeri.
Level 3 Communications and BT, meanwhile, have yet to deploy 100Gbps technology.
"We have not [made any public statements regarding 100 Gig]," says Monisha Merchant, Level 3’s senior director of product management. "We have had trials but nothing formal for our own development." Level 3 started deploying 40Gbps technology in March 2009.
BT expects to deploy new high-speed line rates before the year end. "The first place we are actively pursuing the deployment of initially 40G, but rapidly moving on to 100G, is in the core,” says Steve Hornung, director, transport, timing and synch at BT.
Operators are looking to deploy 100Gbps to meet growing traffic demands.
"If I look at cloud applications, video distribution applications and what we are doing for wireless (Long Term Evolution) - the sum of all the traffic - that is what is putting the strain on the network," says Gringeri.
Verizon is also transitioning its legacy networks onto its core IP-MPLS backbone, requiring the operator to grow its base infrastructure significantly. "When we look at demands there, it is clear that you absolutely need 100 Gig in large parts of the network," says Gringeri.
Level 3 points out its network between any two cities has been running at much greater capacity than 100 Gbps so that demand has been there for years, the issue is the economics of the technology. "Right now, going to 100Gbps is significantly a higher cost than just deploying 10x 10Gbps," says Level 3's Merchant.
BT's core network comprises 106 nodes: 20 in a fully-meshed inner core, surrounded by an outer 86-node core. The core carries the bulk of BT's IP, business and voice traffic.
"We are taking specific steps and have business cases developed to deploy 40G and 100G technology: alternative line cards into the same rack," says Hornung.
Coherent and direct detection
Coherent has become the default optical transmission technology for operators' next-generation core networks.
BT says it is a 'no-brainer' that 400Gbps and 1 Terabit-per-second light paths will eventually be deployed in the network to accommodate growing traffic. "Rather than keep all your options open, we need to make the assumption that technology will essentially be coherent going forward because it will be the bandwidth that drives it," says Hornung.
Beyond BT's 106-node core is a backhaul network that links 1,000 points-of-presence (PoPs). It is this part of the network that BT will consider 40Gbps and perhaps 100Gbps direct-detection technology. "If it [such technology] became commercially available, we would look at the price, the demand and use it, or not, as makes sense," says Hornung. "I would not exclude at this stage looking at any technology that becomes available." Such direct-detection 100Gbps solutions are already being promoted by ADVA Optical Networking and MultiPhy.
However, Verizon believes coherent will also be needed for the metro. "If I look at my metro systems, you have even lower quality amplifiers, and generally worse signal-to-noise," says Gringeri. “Based on the performance required, I have no idea how you are going to implement a solution that isn't coherent."
Even for shorter reach metro systems - 200 or 300km- Verizon believes coherent will be the implementation, including expanding existing deployments that carry 10Gbps light paths and that use dispersion-compensated fibre.
Level 3 says it is not wedded to a technology but rather a cost point. As a result it will assess a technology if it believes it will address the operator's needs and has a cost performance advantage.
100 Gig deployment stages
The cost of 100Gbps technology remains a key challenge impeding wider deployment. This is not surprising since 100Gbps technology is still immature and systems shipping are first-generation designs.
Operators are willing to pay a premium to deploy 100Gbps light paths at network pinch-points as it is cheaper that lighting a new fibre.
Metro deployments of new technology such as 100Gbps occur generally occur once the long-haul network has been upgraded. The technology is by then more mature and better suited to the cost-conscious metro.
Applications that will drive metro 100Gbps include linking data centre and enterprises. But Level 3 expects it will be another five years before enterprises move from requesting 10 Gigabit services to 100 Gigabit ones to meet their telecom needs.
Verizon highlights two 100Gbps priorities: the high-end performance dense WDM systems and client-side 'grey' (non-WDM) optics used to connect equipment across distances as short as 100m with ribbon cable to over 2km or 10km over single-mode fibre.
"I would not exclude at this stage looking at any technology that becomes available"
Steve Hornung, BT
"Grey optics are very costly, especially if I’m going to stitch the network and have routers and other client devices and potential long-haul and metro networks, all of these interconnect optics come into play," says Gringeri.
Verizon is a strong proponent of a new 100Gbps serial interface over 2km or 10km. At present there are the 100 Gigabit interface and the 10x10 MSA. However Gringeri says it will be 2-3 years before such a serial interface becomes available. "Getting the price-performance on the grey optics is my number one priority after the DWDM long haul optics," says Gringeri.
Once 100Gbps client-side interfaces do come down in price, operators' PoPs will be used to link other locations in the metro to carry the higher-capacity services, he says.
The final stage of the rollout of 100Gbps will be single point-to-point connections. This is where grey 100Gbps comes in, says Gringeri, based on 40 or 80km optical interfaces.
Source: Gazettabyte
Tackling costs
Operators are confident regarding the vendors’ cost-reduction roadmaps. "We are talking to our clients about second, third, even fourth generation of coherent," says Gringeri. "There are ways of making extremely significant price reductions."
Gringeri points to further photonic integration and reducing the sampling rate of the coherent receiver ASIC's analogue-to-digital converters. "With the DSP [ASIC], you can look to lower the sampling rate," says Gringeri. "A lot of the systems do 2x sampling and you don't need 2x sampling."
The filtering used for dispersion compensation can also be simpler for shorter-reach spans. "The filter can be shorter - you don't need as many [digital filter] taps," says Gringeri. "There are a lot of optimisations and no one has made them yet."
There are also the move to pluggable CFP modules for the line-side coherent optics and the CFP2 for client-side 100Gbps interfaces. At present the only line-side 100Gbps pluggable is based on direct detection.
"The CFP is a big package," says Gringeri. "That is not the grey optics package we want in the future, we need to go to a much smaller package long term."
For the line-side there is also the issue of the digital signal processor's (DSP) power consumption. "I think you can fit the optics in but I'm very concerned about the power consumption of the DSP - these DSPs are 50 to 80W in many current designs," says Gringeri.
One obvious solution is to move the DSP out of the module and onto the line card. "Even if they can extend the power number of the CFP, it needs to be 15 to 20W," says Gringeri. "There is an awful lot of work to get where you are today to 15 to 20W."
* Monisha Merchant left Level 3 before the article was published.
Further Reading:
100 Gigabit: The coming metro opportunity - a position paper, click here
Click here for Part 2: Next-gen 100 Gig Optics
100 Gigabit: The Coming Metro Opportunity
Gazettabyte has published a Position Paper on the coming 100 Gigabit metro opportunity. (Click here to download a copy.) There has been several announcements in recent weeks from system and component vendors addressing 100 Gigabit metro networks.
The 19-page report looks at the status of the 100 Gigabit market, the drivers for 100 Gigabit deployment, the technology options and their merits. The paper then states how 100 Gigabit technologies such as direct-detection point-to-point, direct-detection WDM and coherent will fare in the metro.
Gazettabyte interviewed over 20 operators, system vendors, optical module and component makers for the Position Paper.
These include ADVA Optical Networks, Alcatel-Lucent, Brocade, BT, BTI Systems, Ciena, Cisco Systems, Cyoptics, John D'Ambrosia - chair of IEEE 100 Gig backplane study group, ECI Telecom, Ericsson, Finisar, Huawei, Infinera, Ixia, Juniper Networks, MultiPhy, Nokia Siemens Networks, Oclaro, Opnext, Level 3 Communications, Transmode, Verizon and ZTE.
Look forward to any comments you may have regarding the report, its position and conclusions.
Transmode chooses coherent for 100 Gigabit metro
Transmode has detailed its 100 Gigabit metro strategy based on a stackable rack, a concept borrowed from the datacom world.
The Swedish system vendor has adopted coherent detection technology for 100 Gigabit-per-second (Gbps) optical transmission, unlike other recent metro announcements from ADVA Optical Networking and MultiPhy based on 100Gbps direct-detection.
"Metro is a little bit diverse. You see different requirements that you have to adapt to."
Sten Nordell, Transmode
"We are getting requests for this and we think 2012 is when people are going to put in a low number of [100Gbps] links into the metro," says Sten Nordell, CTO at Transmode.
The 100Gbps requirements Transmode is seeing include connecting data centres over various distances. The data centres can be close - tens of kilometers - or hundreds of kilometers apart.
"They [data centre operators] want to get more capacity over longer distances over the fibre they have rented," says Nordell. "That is why we are going down the standards path of coherent technology that gives you that boost in power and distance."
Nordell says that customers typically only want one or two 100Gbps light paths to expand fibre capacity or to connect IP routers over a link already carrying multiple 10Gbps light paths. "Metro is a little bit diverse," he says. "You see different requirements that you have to adapt to."
Rack system approach
Transmode has adopted a stackable approach to its 100Gbps TM-series of chassis. The TM-2000 is a 4U-high dual 100Gbps rack that implements transponder, muxponder or regeneration functions. "We have borrowed from Ethernet switches - you add as you grow," says Nordell.
Up to four TM-2000 are used with one TM-301 or TM-3000 master rack, with the architecture supporting up to 80, 100Gbps wavelengths overall.
"If you have too many ROADMs in the way it is going to hurt you. We have seen that with 40 Gig."
The system also uses daughter boards that support various client-side interfaces while keeping the 100Gbps line-side interface - the most expensive system component - intact. "You can install a muxponder of 10x10Gig modules,” says Nordell. "When an IP router upgrades to a 100 Gig interface, you take out the daughter board and put in a 100 Gig transponder."
Transmode will offer two line-side coherent options, with a reach of 750km or 1,500km. "We want to make sure that customers' metro and long-haul requirements will be covered," says Nordell.
The reach of various 100Gbps technologies for the metro edge, core and regional networks. Source: Gazettabyte
The company chose coherent technology because it is an industry-backed standard. "We can benefit from coherent technology," he says. "If the industry aligns, the volumes of the components come down in price."
Coherent also simplifies the setting up and commissioning of agile photonic networks, especially as more ROADMs are introduced in the metro. "Coherent will help simplify this. All the others are more complex," he says. "Beforehand metro was more point-to-point, now we are seeing more flexibility."
Transmode recently announced it is supplying its systems to Virgin Mobile for mobile backhaul. "That is a metro network with all ROADMs in it," says Nordell. Such networks support multiple paths and that translates to a need for greater reach. "The power budget we need to have in the metro is going up a little bit."
Direct-detection technology was considered by Transmode but it chose coherent as it gives customers a better networking design capability.
Direct detection is also not as spectrally efficient as coherent: 200GHz or 100GHz-wide channels for a 100Gbps signal rather that coherent's 50GHz. "If you have too many ROADMs in the way it is going to hurt you, says Nordell.”We have seen that with 40 Gig."
The TM-2000 rack will begin testing in customers' networks at the start of 2012, with limited availability from mid-2012. The platform and daughter boards will be available in volume by year-end 2012.
MultiPhy boosts 100 Gig direct-detection using digital signal processing
The MP1100Q chip is being aimed at two cost-conscious metro networking requirements: 100 Gigabit point-to-point links and dense wavelength-division multiplexing (DWDM) metro networks.
The MP1100Q as part of a 100 Gig CFP module design. Source: MultiPhy
The 100 Gigabit market is still in its infancy and the technology has so far been used to carry traffic across operators’ core networks. Now 100 Gigabit metro applications are emerging.
Data centre operators want short links that go beyond the IEEE-specified 10km (100GBASE-LR4) and 40km (100GBASE-ER4) reach interfaces, while enterprises are looking to 100 Gigabit-per-second (Gbps) DWDM solutions to boost the capacity and reach of their rented fibre. Existing 100Gbps coherent technologies, designed for long-haul, are too expensive and bulky for the metro.
“There is long-haul and the [IEEE] client interfaces and a huge gap in between,” says Avishay Mor, vice president of product management at MultiPhy.
It is this metro 'gap' that MultiPhy is targeting with its MQ1100Q chip. And the fabless chip company's announcement is one of several that have been made in recent weeks.
ADVA Optical Networking has launched a 100Gbps metro line card that uses a direct-detection CFP, while Transmode has detailed a 100Gbps coherent design tailored for the metro. The 10x10 MSA announced in August a 10km interface as well as a 40km WDM design alongside its existing 10x10Gbps MSA that has a 2km reach.
MultiPhy's MP1100Q IC will enable two CFP module designs: a point-to-point module to connect data centres with a reach of up to 80km, and a DWDM design for metro core and regional networks with a reach up to 800km.
"MLSE is recognised as the best solution for mitigating inter-symbol interference."
Design details
The M1100Q uses a 4x28Gbps direct-detection design, the same approach announced by ADVA Optical Networking for its 100Gbps metro card. But MultiPhy claims that the 100Gbps DWDM CFP module will squeeze the four bands that make up the 100Gbps signal into a 100GHz-wide channel rather than 200GHz, while its IC implements the maximum likelihood sequence estimation (MLSE) algorithm to achieve the 800km reach.
The four optical channels received by a CFP are converted to electrical signals using four receiver optical subassemblies (ROSAs) and sampled using the MP1100Q’s four analogue-to-digital (a/d) converters operating at 28Gbps.
The CFP design using MultiPhy’s chip need only use 10Gbps opto-electronics for the transmit and receive paths. The result is a 100Gbps module with a cost structure based on 4x10Gbps optics.
The lower bill-of-materials impacts performance, however. “When you over-drive these 10Gbps opto-electronics - on the transmit and the receive side - you create what is called inter-symbol interference," says Neal Neslusan, vice president of sales and marketing at MultiPhy.
Inter-symbol interference is an unwanted effect where the energy of a transmitted bit leaks into neighboring signals. This increases the bit-error rate and makes the detector's task harder. "The way that we get around it is using MLSE, recognised as the best solution for mitigating inter-symbol interference," says Neslusan.
Unwanted channel effects introduced by the fibre, like chromatic dispersion, also induce inter-symbol interference and are also countered by the MLSE algorithm on the MP1100Q.
MultiPhy is proposing two CFP designs for its chip. One is based on on-off-keying modulation to achieve 80km point-to-point links and which will require a 200GHz channel to accommodate the 100Gbps signal. The second uses optical duo-binary modulation to achieve the longer reach and more spectrally efficient 100GHz spacings.
The company says the resulting direct-detection CFP using its IC will cost some US $10,000 compared to an estimated $50,000 for a coherent design. In turn the 100G metro CFP’s power consumption is estimated at 24W whereas a coherent design consumes 70W.
MP1100Q samples have been with the company since June, says Mor. First samples will be with customers in the fourth quarter of this year, with general availability starting in early 2012.
If all goes to plan, first CFP module designs using the chip will appear in the second half of 2012, claims MultiPhy.
High fives: 5 Terabit OTN switching and 500 Gig super-channels.
Infinera has announced a core network platform that combines Optical Transport Network (OTN) switching with dense wavelength division multiplexing (DWDM) transport. "We are looking at a system that integrates two layers of the network," says Mike Capuano, vice president of corporate marketing at Infinera.
"This is 100Tbps of non-blocking switching, all functioning as one system. You just can't do that with merchant silicon."
Mike Capuano, Infinera
The DTN-X platform is based on Infinera's third-generation photonic integrated circuit (PIC) that supports five, 100Gbps coherent channels.
Each DTN-X platform can deliver 5 Terabits-per-second (Tbps) of non-blocking OTN switching using an Infinera-designed ASIC. Ten DTN-X platforms can be combined to scale the OTN switching and transport capacity to 50Tbps currently.
Infinera also plans to add Multiprotocol Label Switching (MPLS) to turn the DTN-X into a hybrid OTN/ MPLS switch. With the next upgrades to the PIC and the switching, the ten DTN-X platforms will scale to 100Tbps optical transport and 100Tbps OTN and MPLS switching capacity.
The platform is being promoted by Infinera as a way for operators to tackle network traffic growth and support developments such as cloud computing where applications and content increasingly reside in the network. "What that means [for cloud-based services to work] is a network with huge capacity and very low latency," says Capuano.
Platform details
The 5x100Gbps PIC supports what Infinera calls a 500Gbps 'super-channel'. Each super-channel is a multi-carrier implementation comprising five, 100Gbps wavelengths. Combined with OTN, the 500Gbps super-channel can be filled with 1, 10, 40 and 100 Gigabit streams (SONET/SDH, Ethernet, video etc). Moreover, there is no spectral efficiency penalty: the super-channel uses 250GHz of fibre spectrum, provisioning five 50GHz-wide, 100Gbps wavelengths at a time.
"We have seen 40 and 100Gbps come on the market and they are definitely helping with fibre capacity issues," says Capuano. "But they are more expensive from a cost-per-bit perspective than 10Gbps." By introducing the 500Gbps PIC, Infinera says it is reducing the cost-per-bit performance of high speed optical transport.
DTN-X: shown are 5 line and tributary cards top and bottom with switching cards in the centre of the chassis. Source: Infinera
Integrating OTN switching within the platform results in the lowest cost solution and is more efficient when compared to multiplexed transponders (muxponder) configured manually, or an external OTN switch which must be optically connected to the transport platform.
The DTN-X also employs Generalised MPLS (GMPS) software. "GMPLS makes it easy to deploy networks and services with point-and-click provisioning," says Capuano.
Each DTX-N line card supports a 500Gbps PIC but the chassis backplane is specified at 1Tbps, ready for Infinera's next-generation 10x100Gbps PIC that will upgrade the DTN-X to a 10Tbps system. "We have already presented our test results for our 1Tbps PIC back in March," says Capuano. The fourth-generation PIC, estimated around 2014 (based on a company slide although Infinera has made no public comment), will support a 1Tbps super-channel.
Adding MPLS will add the transport capability of the protocol to the DTN-X. "You will have MPLS transport, OTN switching and DWDM all in one platform," says Capuano.
OTN switching is the priority of the tier-one operators to carry and process their SONET/SDH traffic; adding MPLS will enable extra traffic processing capabilities to the system, he says.
Infinera says that by eventually integrating MPLS switching into the optical transport network, operators will be able to bypass expensive router ports and simplify their network operation.
Performance
Infinera says that the DTX-N 5Tbps performance does not dip however the system is configured: whether solely as a switch (all line card slots filled with tributary modules), mixed DWDM/ switching (half DWDM/ half tributaries, for example) or solely as a DWDM platform. Depending on the cards in the DTN-X platform, the transport/ switching configuration can be varied but the 5Tbps I/O capacity is retained. Infinera says other switches on the market do lose I/O capacity as the interface mix is varied.
Overall, Infinera claims the platform requires half the power of competing solutions and takes up a third less space.
The DTN-X will be available in the first half of 2012.
Analysis
Gazettabyte asked several market research firms about the significance of the DTN-X announcement and the importance of combining OTN, DWDM and soon MPLS within one platform.
Ovum
Ron Kline, principal analyst, and Dana Cooperson, vice president, of the network infrastructure practice
"MPLS switching is setting up a very interesting competitive dynamic among vendors"
Dana Cooperson, Ovum
The DTN-X is a platform for the largest service providers and their largest sites, says Ovum.
It sees the DTN-X in the same light as other integrated OTN/ WDM platforms such as Huawei's OSN 8800, Nokia Siemens Networks' hiT 7100, Alcatel-Lucent's 1830 PSS and Tellabs' 7100 OTS.
"It fits the mold for Verizon's long-haul optical transport platform (LH OTP), especially once MPLS is added," says Kline. "NSN is also claiming it will add MPLS to the 7100. Once MPLS is added, then you have the big packet optical transport box that Verizon wants."
The DTN-X platform will boost the business case for 100 Gig in a similar way to how Infinera's current PIC has done at 10 Gig. "The others will be forced to lower price," says Kline.
Having GMPLS is important, especially if there is a need to do dynamic bandwidth allocation, however it is customer-dependent. "When you start digging, it's hard to find large-scale implementations of GMPLS," says Kline.
The Ovum analysts stress that the need for OTN in the core depends on the customer. Content service providers like Google couldn't care less about OTN. "It's really an issue for multi-service providers like BT and AT&T," says Cooperson,
There is a consensus about the need for MPLS in the core. "Different service providers are likely to take different approaches — some might prefer an integrated box and others might not, it depends on their business," she says. "I think MPLS switching is setting up a very interesting competitive dynamic among vendors that focus on IP/MPLS, those that focus on optical, and those that are trying to do both [optical and IP/MPLS].
Ovum highlights several aspects regarding the DTN-X's claimed performance.
"Assuming it performs as advertised, this should finally give Infinera what it needs to be of real interest to the tier-ones," says Cooperson. "The message of scalability, simplicity, efficiency, and profitability is just what service providers want to hear."
Cooperson also highlights Infinera's approach to optical-electrical-optical conversion and the benefit this could deliver at line speeds greater than 100Gbps.
At present ROADMs are being upgraded to support flexible spectrum channel configurations, also known as gridless. This is to enable future line speeds that will use more spectrum than current 50GHz DWDM channels. Operators want ROADMs that support flexible spectrum requirements but managing the network to support these variable width channels is still to resolved.
"It fits the mold for Verizon's long-haul optical transport platform (LH OTP), especially once MPLS is added"
Ron Kline, Ovum
Infinera's approach is based on conversion to the electrical domain when dropping and regenerating wavelengths such that the issue of flexible channels does not arise or is at least forestalled. This, says Cooperson, could be Infinera's biggest point of differentiation.
"What impresses me is the 500Gbps super-channel using five, 100Gbps carriers and the size of the switch fabric," adds Kline. The 5Tbps switching performance also exceeds that of everyone else: "Alcatel-Lucent is closest with 4Tbps but most range from 1-3Tbps and top out at 3Tbps."
The ease of use is also a big deal. Infinera did very well in marketing rapid turn up: 10 Gig in 10 days for example, says Kline: "It looks like they will be able to do the same here with 100 Gig."
Infonetics Research
Andrew Schmitt, directing analyst, optical
"GMPLS isn't that important, yet."
The DTN-X is a WDM platform which optionally includes a switch fabric for carriers that want it integrated with the transport equipment, says Schmitt. Once MPLS is added, it has the potential to be a full-blown packet-optical system.
"[The announcement is] pretty significant though not unexpected," says Schmitt. "I think the key question is what it costs, and whether the 500G PIC translates into compelling savings."
Having MPLS support is important for some carriers such as XO Communications and Google but not for others.
Schmitt also says GMPLS isn't that important, yet. "Infinera's implementation of regen-rich networks should make their GMPLS implementation workable," he says. "It has been building networks like that for a while."
OTN in the core is still an open debate but any carrier that doesn't have the luxury of a homogenous data network needs it, he says
Schmitt has yet to speak with carriers who have used the DTN-X: "I can't comment on claimed performance but like I said, cost is important."
ACG Research
Eve Griliches, managing partner
"Infinera has already introduced the 500G PIC, but the OTN is significant in that it can be used as a standalone OTN switch, and it has the largest capacity out there today"
The DTN-X as an OTN/ WDM platform awaiting label switch router (LSR) functionality, says Griliches: "With the LSR functionality it will be able to do statistical multiplexing for direct router connections."
Infinera has already introduced the 500 Gig PIC but the OTN is significant in that it can be used as a standalone OTN switch, and it has the largest capacity out there today. An OTN survey conducted last year by ACG Research found that the switch capacity sweet spot is between 4 and 8Tbps.
Griliches says that LSR-based products are taking time to incorporate WDM and OTN technologies, while it is unclear when the DTN-X will support MPLS to add LSR capabilities. The race is on as to whom can integrate everything first, but DWDM and OTN before MPLS is the right direction for most tier-one operators, she says.
Infinera has over eight thousand of its existing DTNs deployed at 85 customers in 50 countries. The scale of the DTN-X will likely broaden Infinera's customer base to include tier-one operators, says Griliches.
ACG Research has heard positive feedback from operators it has spoken to. One stressed that the decreased port count due to the larger OTN cross-connect significantly improves efficiencies. Another operator said it would pick Infinera and said the beta version of the 500Gbps PIC is "working beautifully".