Infinera adds software to its PIC for instant bandwidth

Infinera has enabled its DTN-X platform to deliver rapidly 100 Gigabit services. The ability to fulfill capacity demand quickly is seen as a competitive advantage by operators. Gazettabyte spoke with Infinera and TeliaSonera International Carrier, a DTN-X customer, about the merits of its 'instant bandwidth' and asked several industry analysts for their views.


Infinera has added a WDM line card hosting its 500 Gigabit super-channel photonic integrated circuit to its DTN-X platform

Pravin Mahajan, Infinera.

 

Infinera is claiming an industry first with the software-enablement of 100 Gigabit capacity increments. The company's DTN-X platform's 'instant bandwidth' feature shortens the time to add new capacity in the network, from weeks as is common today to less than a day.

The ability to add bandwidth as required is increasingly valued by operators. TeliaSonera International Carrier points out that its traffic demands are increasingly variable, making capacity requirements harder to forecast and manage. 

"It [the DTN-X's instant bandwidth] enables us to activate 100 Gig services between network spans to manage our own IP traffic which is growing rapidly," says Ivo Pascucci, head of sales, Americas at TeliaSonera International Carrier. "We will also be able to sell in the market 100 Gig services and activate the capacity much more rapidly."

 

What has been done

Infinera has added three elements to enable its DTN-X platform to enable 100 Gigabit services.

One is a new wavelength division multiplexing (WDM) line card that features its 500 Gigabit-per-second (Gbps) super-channel photonic integrated circuit (PIC). Infinera says the line card has 500Gbps of capacity enabled, of which only 100Gbps is activated. "The remaining 400Gbps is latent, waiting to be activated," says Pravin Mahajan, director of corporate marketing and messaging at Infinera.

Infinera uses the DTN-X's Optical Transport Network (OTN) switch fabric to pack the client side signals onto any of the 100Gbps channels activated on the line side. This capacity pool of up to 500 Gbps, says Infinera, results in better usage of backbone capacity compared to traditional optical networking equipment based on individual 100Gbps 'siloed' channels.

A software application has also been added to Infinera's network management system, the digital network administrator (DNA), to activate the 100Gbps capacity increments.

Lastly, Infinera has in place a just-in-time system that enables client-side 10 Gigabit Ethernet optical transceivers to be delivered to customers within 10 days, if they out of stock. Infinera says it is achieving a 6-day delivery time in 95% of the cases.

 

 

Advantages

TeliaSonera International Carrier confirms the advantages to having 100 Gigabit capacities pre-provisioned and ready for use.

 

"Having the ability to turn up large bandwidth is critical to our business, especially as the [traffic] numbers continue to grow"  

Ivo Pascucci, TeliaSonera International Carrier

 

 

"If it is individual line cards across the network when you have as many PoPs as we do, it does get tricky," says Pascucci. "If we have 500 Gig channels pre-provisioned with the ability to activate 100 Gig segments as needed, that gives us an advantage versus having to figure out how many line cards to have deployed in which nodes, and forecasting which nodes should have the line cards in the first place." 

The operator is already seeing demand for 100 Gigabit services, from the carrier market and large content providers. The operator already provides 10x10Gbps and 20x10Gbps services to customers. "With that there are all the challenges of provisioning ten or 20 10 Gig circuits and 10 or 20 cross-connects for each site," says Pascucci.  The operator also manages one and two Terabits of network capacity for certain customers. 

"Having the ability to turn up large bandwidth is critical to our business, especially as the [traffic] numbers continue to grow," says Pascucci.

 

Analysts' comments

Gazettabye asked several industry analysts about the significance of Infinera's announcement. In particular the uniqueness of the offering, the claim to reduce rapidly bandwidth enablement times and its importance for operators.

 

Infonetics Research

Andrew Schmitt, directing analyst for optical

Schmitt believes Infinera's announcement is significant as it is the first announced North American win. It also shows the company has a solution for carriers that only want to roll out a single 100 Gbps but don't want to buy 500Gbps.

More importantly, it should allow some carriers to deploy extra capacity for future use at no cost to them and that opens up interesting possibilities for automatically switched optical network (ASON) management or even software-defined networking (SDN).

"As to the claim that it reduces capacity enablement from weeks to potential minutes, to some degree, yes," says Schmitt.

Certainly Ciena, Alcatel-Lucent or Cisco could ship extra line cards into customers and not charge the customer until they are used and that would effectively achieve the same result. "But if the PIC truly has better economics than the discrete solutions from these vendors then Infinera can ship hardware up front and then recognise the profits on the back end," he says.

 

"You simply can't predict where the best places to put bandwidth will be" 

 

In turn, if customers get free inventory management out of the deal and Infinera equipment can support that arrangement more economically, that is a significant advantage for Infinera.

"This instant bandwidth is unique to Infinera. As I said, anyone could do this deal. But you need a hardware cost structure that can support it or it gets expensive quickly," says Schmitt. "Everyone is working on super-channels but it is clear from the legacy of the way the 10 Gig DTN hardware and software worked that Infinera gets it."

Schmitt believes the term super-channel is abused. He prefers the term virtualised bandwidth - optical capacity that can be allocated the same way server or storage resources are assigned through virtualization.

"The SDN hype is hitting strong in this business but Infinera is really one of the only companies that have a history of a hardware and software architecture that lends itself well to this concept," he says. This is validated with its customer list which is loaded heavily with service providers that are not just talking about SDN but actively doing something, he says.

"It [turning capacity up quickly] is important for SDN as well as more advanced protection arrangements. You simply can't predict where the best places to put bandwidth will be," says Schmitt. "If you can have spare capacity in the network that is lit on demand but not paid for if you don't need it, it is the cheapest approach for avoiding overbuilding a network for corner-case requirements.

"I think the accounting for this product will be interesting, it is likely that we will know in a year how successful this concept was just by a careful examination of the company's financials," he concludes.

 

ACG Research

Eve Griliches, vice president of optical networking

Infinera delivered this year the DTN-X with 500 Gig super-channels based on PIC technology. Now, a new 500 Gig line card has been added that can operate at 100 Gig and the remaining 400 Gig can be lit in 100 Gig increments using software. This allows customers to purchase 100 Gig at a time, and turn up subsequent bandwidth via software when they require it.

“No other vendor has a software-based solution, and no one else is delivering 500 Gig yet either,” says Griliches.

With this solution, ACG Research says in its research note, operators can start to develop a flexible infrastructure where bandwidth can grow and move around the network instantly. This is useful to address varying demands in bandwidth, triggered by incidents such as natural disasters or sporting events.

Rapid bandwidth enablement has always been important and takes way too long, so this development is key, says Griliches: “Also, it enables Infinera to enter markets which only need one 100 Gig wavelength for now, which they could not do before.”

 

“No other vendor has a software-based solution, and no one else is delivering 500 Gig yet either”

 

Looking forward, ACG Research expects this software and hardware-based instant bandwidth utility model will enable Infinera to widen its potential market base and increase its global market share in 2013 and 2014.

 

Ovum

Ron Kline, principal analyst, and Dana Cooperson, vice president, of the network infrastructure practice

Ovum also thinks Infinera's announcement is significant. It brings essentially the same value proposition Infinera had with 10 Gigabit to the 100 Gigabit market - low operational expenditure (opex) and quick time-to-market. ”Remember 10 Gig in 10 days?” says Kline.

It further fixes an issue for customers in that with the 10x10Gbps, they had to essentially pay for the full 100Gbps up front, and then they could be very efficient with turn-up and opex. Customers made an efficient opex for more capital expenditure (capex) up-front trade. "With instant bandwidth, they don't have to make the upfront capex-versus-opex tradeoff; they can be most efficient with both,” says Cooperson.

 

Any vendor can shorten capacity enablement times if they can convince the operator to pre-position bandwidth in the network that is ready to be turned on at a moment's notice.

Ron Kline

 

Kline says operators has different processes for turning up services and in many cases it is these processes and not the equipment directly that is the cause of the additional time for provisioning. “For example the operator may not use the DNA system or may have a very complex OSS/BSS used in the process,” says Kline.

Nevertheless, the capability to have really short provisioning is there, if an operator wants to take advantage. In the TeliaSonera case, Infinera is managing the network so the quick time to market will be there, says Kline.

Cooperson adds that there can be many factors that impede the capacity enablement process, based on Ovum's own research. “But it is clear from talking to Infinera's customers that its system design and approach is a big benefit to those carriers, often the competitive carriers, in competing in the market,” she says. “Multiple carriers told us that with the Infinera system, they were able to win business from competitors.”

Any vendor can shorten capacity enablement times if they can convince the operator to pre-position bandwidth in the network that is ready to be turned on at a moment's notice. However what is unique to Infinera is its system is deployed 500Gbps at a time and all the switching is done electrically by the OTN switch at each node. Others are working on super-channels but none are close to deploying, says Ovum.

 

“Multiple carriers told us that with the Infinera system, they were able to win business from competitors.”

Dana Cooperson

 

The ability to turn on bandwidth rapidly is becoming increasingly important. From a wholesale operator perspective it is very important and a key differentiator.

"It's particularly relevant to wholesale applications where large bandwidth chunks are required and the customer is another carrier," says Cooperson. "Whether you view a Google or a Facebook as a carrier or a very large enterprise, it would apply to them as well as a more traditional carrier."


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". 


Infinera details Terabit PICs, 5x100G devices set for 2012

What has been announced?

Infinera has given first detail of its terabit coherent detection photonic integrated circuits (PICs). The pair - a transmitter and a receiver PIC – implement a ten-channel 100 Gigabit-per-second (Gbps) link using polarisation multiplexing quadrature phase-shift keying (PM-QPSK). The Infinera development work was detailed at OFC/NFOEC held in Los Angeles between March 6-10.

Infinera has recently demonstrated its 5x100Gbps PIC carrying traffic between Amsterdam and London within Interoute Communications’ pan-European network. The 5x100Gbps PIC-based system will be available commercially in 2012.

 

“We think we can drive the system from where it is today – 8 Terabits-per-fibre - to around 25 Terabits-per-fibre”

Dave Welch, Infinera 

 

Why is this significant?

The widespread adoption of 100Gbps optical transport technology will be driven by how quickly its cost can be reduced to compete with existing 40Gbps and 10Gbps technologies.

Whereas the industry is developing 100Gbps line cards and optical modules, Infinera has demonstrated a 5x100Gbps coherent PIC based on 50GHz channel spacing while its terabit PICs are in the lab. 

If Infinera meets its manufacturing plans, it will have a compelling 100Gbps offering as it takes on established 100Gbps players such as Ciena. Infinera has been late in the 40Gbps market, competing with its 10x10Gbps PIC technology instead.

 

40 and 100 Gigabit 

Infinera views 40Gbps and 100Gbps optical transport in terms of the dynamics of the high-capacity fibre market. In particular what is the right technology to get most capacity out of a fibre and what is the best dollar-per-Gigabit technology at a given moment.

For the long-haul market, Dave Welch, chief strategy officer at Infinera, says 100Gbps provides 8 Terabits (Tb) of capacity using 80 channels versus 3.2Tb using 40Gbps (80x40Gbps). The 40Gbps total capacity can be doubled  to 6.4Tb (160x40Gbps) if 25GHz-spaced channels are used, which is Infinera’s approach.

“The economics of 100 Gigabit appear to be able to drive the dollar-per-gigabit down faster than 40 Gigabit technology,” says Welch. If operators need additional capacity now, they will adopt 40Gbps, he says, but if they have spare capacity and can wait till 2012 they can use 100Gbps. “The belief is that they [operators] will get more capacity out of their fibre and at least the same if not better economics per gigabit [using 100Gbps],” says Welch. Indeed Welch argues that by 2012, 100Gbps economics will be superior to 40Gbps coherent leading to its “rapid adoption”.

For metro applications, achieving terabits of capacity in fibre is less of a concern. What matters is matching speeds with services while achieving the lowest dollar-per-gigabit. And it is here – for sub-1000km networks – where 40Gbps technology is being mostly deployed. “Not for the benefit of maximum fibre capacity but to protect against service interfaces,” says Welch, who adds that 40 Gigabit Ethernet (GbE) rather than 100GbE is the preferred interface within data centres.

 

Shorter-reach 100Gbps

Companies such as ADVA Optical Networking and chip company MultiPhy highlight the merits of an additional 100Gbps technology to coherent based on direct detection modulation for metro applications (for a MultiPhy webinar on 100Gbps direct detection, click here). Direct detection is suited to distances from 80km up to 1000km, to connect data centres for example.

Is this market of interest to Infinera?  “This is a great opportunity for us,” says Welch.

The company’s existing 10x10Gbps PIC can address this segment in that it is least 4x cheaper than emerging 100Gbps coherent solutions over the next 18 months, says Welch, who claims that the company’s 10x10Gbps PIC is making ‘great headway’ in the metro.

“If the market is not trying to get the maximum capacity but best dollar-per-gigabit, it is not clear that full coherent, at least in discrete form, is the right answer,” says Welch. But the cost reduction delivered by coherent PIC technology does makes it more competitive for cost-sensitive markets like metro.

A 100Gbps coherent discrete design is relatively costly since it requires two lasers (one as a local oscillator (LO - see fig 1 - at the receiver), sophisticated optics and a high power-consuming digital signal processor (DSP). “Once you go to photonic integration the extra lasers and extra optics, while a significant engineering task, are not inhibitors in terms of the optics’ cost.”

Coherent PICs can be used ‘deeper in the network’ (closer to the edge) while shifting the trade-offs between coherent and on-off keying. However even if the advent of a PIC makes coherent more economical, the DSP’s power dissipation remains a factor regarding the tradeoff at 100Gbps line rates between on-off keying and coherent.

Welch does not dismiss the idea of Infinera developing a metro-centric PIC to reduce costs further. He points out that while such a solution may be of particular interest to internet content companies, their networks are relatively simple point-to-point ones. As such their needs differ greatly from cable operators and telcos, in terms of the services carried and traffic routing.

 

PIC challenges

Figure 1: Infinera's terabit PM-QPSK coherent receiver PIC architecture

There are several challenges when developing multi-channel 100Gbps PICs.  “The most difficult thing going to a coherent technology is you are now dealing with optical phase,” says Welch. This requires highly accurate control of the PIC’s optical path lengths.

The laser wavelength is 1.5 micron and with the PIC's indium phosphide waveguides this is reduced by a third to 0.5 micron. Fine control of the optical path lengths is thus required to tenths of a wavelength or tens of nanometers (nm).

Achieving a high manufacturing yield of such complex PICs is another challenge. The terabit receiver PIC detailed in the OFC paper integrates 150 optical components, while the 5x100Gbps transmit and receive PIC pair integrate the equivalent of 600 optical components.

Moving from a five-channel (500Gbps) to a ten-channel (terabit) PIC is also a challenge. There are unwanted interactions in terms of the optics and the electronics. “If I turn one laser on adjacent to another laser it has a distortion, while the light going through the waveguides has potential for polarisation scattering,” says Welch. “It is very hard.” 

But what the PICs shows, he says, is that Infinera’s manufacturing process is like a silicon fab’s. “We know what is predictable and the [engineering] guys can design to that,” says Welch. “Once you have got that design capability, you can envision we are going to do 500Gbps, a terabit, two terabits, four terabits – you can keep on marching as far as the gigabits-per-unit [device] can be accomplished by this technology.”

The OFC post-deadline paper details Infinera's 10-channel transmitter PIC which operates at 10x112Gbps or 1.12Tbps.

 

Power dissipation

The optical PIC is not what dictates overall bandwidth achievable but rather the total power dissipation of the DSPs on a line card. This is determined by the CMOS process used to make the DSP ASICs, whether 65nm, 40nm or potentially 28nm.

Infinera has not said what CMOS process it is using. What Infinera has chosen is a compromise between “being aggressive in the industry and what is achievable”, says Welch. Yet Infinera also claims that its coherent solution consumes less power than existing 100Gbps coherent designs, partly because the company has implemented the DSP in a more advanced CMOS node than what is currently being deployed. This suggests that Infinera is using a 40nm process for its coherent receiver ASICs. And power consumption is a key reason why Infinera is entering the market with a 5x100Gbps PIC line card. For the terabit PIC, Infinera will need to move its ASICs to the next-generation process node, he says.

Having an integrated design saves power in terms of the speeds that Infinera runs its serdes (serialiser/ deserialiser) circuitry and the interfaces between blocks. “For someone else to accumulate 500Gbps of bandwdith and get it to a switch, this needs to go over feet of copper cable, and over a backplane when one 100Gbps line card talks to a second one,” says Welch. “That takes power - we don’t; it is all right there within inches of each other.”

Infinera can also trade analogue-to-digital (A/D) sampling speed of its ASIC with wavelength count depending on the capacity required. “Now you have a PIC with a bank of lasers, and FlexCoherent allows me to turn a knob in software so I can go up in spectral efficiency,” he says, trading optical reach with capacity. FlexCoherent is Infinera’s technology that will allow operators to choose what coherent optical modulation format to use on particular routes. The modulation formats supported are polarisation multiplexed binary phase-shift keying (PM-BPSK) and PM-QPSK.

 

Dual polarisation 25Gbaud constellation diagrams

What next?

Infinera says it is an adherent of higher quadrature amplitude modulation (QAM) rates to increase the data rate per channel beyond 100Gbps. As a result FlexCoherent in future will enable the selection of higher-speed modulation schemes such as 8-QAM and 16-QAM. “We think we can drive the system from where it is today –8 Terabits-per-fibre - to around 25 Terabits-per-fiber.”

But Welch stresses that at 16-QAM and even higher level speeds must be traded with optical reach. Fibre is different to radio, he says. Whereas radio uses higher QAM rates, it compensates by increasing the launch power. In contrast there is a limit with fibre. “The nonlinearity of the fibre inhibits higher and higher optical power,” says Welch. “The network will have to figure out how to accommodate that, although there is still significant value in getting to that [25Tbps per fibre]” he says.

The company has said that its 500 Gigabit PIC will move to volume manufacturing in 2012. Infinera is also validating the system platform that will use the PIC and has said that it has a five terabit switching capacity.

Infinera is also offering a 40Gbps coherent (non-PIC-based) design this year. “We are working with third-party support to make a module that will have unique performance for Infinera,” says Welch.

The next challenge is getting the terabit PIC onto the line card. Based on the gap between previous OFC papers to volume manufacturing, the 10x100Gbps PIC can be expected in volume by 2014 if all goes to plan.

 


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