ECOC reflections: final part
Gazettabyte asked several attendees at the recent ECOC show, held in Cannes, to comment on key developments and trends they noted, as well as the issues they will track in the coming year.
Dr. Ioannis Tomkos, Fellow of OSA & Fellow of IET, Athens Information Technology Center (AIT)
With ECOC 2014 celebrating its 40th anniversary, the technical programme committee did its best to mark the occasion. For example, at the anniversary symposium, notable speakers presented the history of optical communications. Actual breakthroughs discussed during the conference sessions were limited, however.
Ioannis Tomkos
It appears that after 2008 to 2012, a period of significant advancements, the industry is now more mainstream, and significant shifts in technologies are limited. It is clear that the original focus four decades ago on novel photonics technologies is long gone. Instead, there is more and more of a focus on high-speed electronics, signal processing algorithms, and networking. These have little to do with photonics even if they greatly improve the overall efficient operation of optical communication systems and networks.
Coherent detection technology is making its way in metro with commercial offerings becoming available, while in academia it is also discussed as a possible solution for future access network applications where long-reach, very-high power budgets and high-bit rates per customer are required. However, this will only happen if someone can come up with cost-effective implementations.
Advanced modulation formats and the associated digital signal processing are now well established for ultra-high capacity spectral-efficient transmission. The focus in now on forward-error-correction codes and their efficient implementations to deliver the required differentiation and competitive advantage of one offering versus another. This explains why so many of the relevant sessions and talks were so well attended.
There were several dedicated sessions covering flexible/ elastic optical networking. It was also mentioned in the plenary session by operator Orange. It looks like a field that started only fives years ago is maturing and people are now convinced about the significant short-term commercial potential of related solutions. Regarding latest research efforts in this field, people have realised that flexible networking using spectral super-channels will offer the most benefit if it becomes possible to access the contents of the super-channels at intermediate network locations/ nodes. To achieve that, besides traditional traffic grooming approaches such as those based on OTN, there were also several ground-breaking presentations proposing all-optical techniques to add/ drop sub-channels out of the super-channel.
Progress made so far on long-haul high-capacity space-division-multiplexed systems, as reported in a tutorial, invited talks and some contributed presentations, is amazing, yet the potential for wide-scale deployment of such technology was discussed by many as being at least a decade away. Certainly, this research generates a lot of interesting know-how but the impact in the industry might come with a long delay, after flexible networking and terabit transmission becomes mainstream.
Much attention was also given at ECOC to the application of optical communications in data centre networks, from data-centre interconnection to chip-to-chip links. There were many dedicated sessions and all were well attended.
Besides short-term work on high-bit-rate transceivers, there is also much effort towards novel silicon photonic integration approaches for realising optical interconnects, space-division-multiplexing approaches that for sure will first find their way in data centres, and even efforts related with the application of optical switching in data centres.
At the networking sessions, the buzz was around software-defined networking (SDN) and network functions virtualisation (NFV) now at the top of the “hype-cycle”. Both technologies have great potential to disrupt the industry structure, but scientific breakthroughs are obviously limited.
As for my interests going forward, I intend to look for more developments in the field of mobile traffic front-haul/ back-haul for the emerging 5G networks, as well as optical networking solutions for data centres since I feel that both markets present significant growth opportunities for the optical communications/ networking industry and the ECOC scientific community.
Dr. Jörg-Peter Elbers, vice president advanced technology, CTO Office, ADVA Optical Networking
The top topics at ECOC 2014 for me were elastic networks covering flexible grid, super-channels and selectable higher-order modulation; transport SDN; 100-Gigabit-plus data centre interconnects; mobile back- and front-hauling; and next-generation access networks.
For elastic networks, an optical layer with a flexible wavelength grid has become the de-facto standard. Investigations on the transceiver side are not just focussed on increasing the spectral efficiency, but also at increasing the symbol rate as a prospect for lowering the number of carriers for 400-Gigabit-plus super-channels and cost while maintaining the reach.
Jörg-Peter Elbers
As we approach the Shannon limit, spectral efficiency gains are becoming limited. More papers were focussed on multi-core and/or few-mode fibres as a way to increase fibre capacity.
Transport SDN work is focussing on multi-tenancy network operation and multi-layer/ multi-domain network optimisation as the main use cases. Due to a lack of a standard for north-bound interfaces and a commonly agreed information model, many published papers are relying on vendor-specific implementations and proprietary protocol extensions.
Direct detect technologies for 400 Gigabit data centre interconnects are a hot topic in the IEEE and the industry. Consequently, there were a multitude of presentations, discussions and demonstrations on this topic with non-return-to-zero (NRZ), pulse amplitude modulation (PAM) and discrete multi-tone (DMT) being considered as the main modulation options. 100 Gigabit per wavelength is a desirable target for 400 Gig interconnects, to limit the overall number of parallel wavelengths. The obtainable optical performance on long links, specifically between geographically-dispersed data centres, though, may require staying at 50 Gig wavelengths.
In mobile back- and front-hauling, people increasingly recognise the timing challenges associated with LTE-Advanced networks and are looking for WDM-based networks as solutions. In the next-generation access space, components and solutions around NG-PON2 and its evolution gained most interest. Low-cost tunable lasers are a prerequisite and several companies are working on such solutions with some of them presenting results at the conference.
Questions around the use of SDN and NFV in optical networks beyond transport SDN point to the access and aggregation networks as a primary application area. The capability to programme the forwarding behaviour of the networks, and place and chain software network functions where they best fit, is seen as a way of lowering operational costs, increasing network efficiency and providing service agility and elasticity.
What did I learn at the show/ conference? There is a lot of development in optical components, leading to innovation cycles not always compatible with those of routers and switches. In turn, the cost, density and power consumption of short-reach interconnects is continually improving and these performance metrics are all lower than what can be achieved with line interfaces. This raises the question whether separating the photonic layer equipment from the electronic switching and routing equipment is not a better approach than building integrated multi-layer god-boxes.
There were no notable new trends or surprises at ECOC this year. Most of the presented work continued and elaborated on topics already identified.
As for what we will track closely in the coming year, all of the above developments are of interesting. Inter-data centre connectivity, WDM-PON and open programmable optical core networks are three to mention in particular.
For the first ECOC reflections, click here
Ericsson and Ciena collaborate on IP-over-WDM and SDN
Jan Häglund
Ericsson and Ciena have signed a global strategic agreement that provides Ericsson with Ciena's optical networking technology, while Ciena benefits from Ericsson's broader service provider relationships.
In particular, Ciena's WaveLogic coherent optical processor will be integrated into a module and added to Ericsson's Smart Service IP routers, while Ericsson will resell Ciena's 6500 Packet-Optical Platform and 5400 Reconfigurable Switching Systems.
Both companies will also collaborate in developing SDN in the WAN, also known as service provider SDN or Transport SDN.
IP-over-WDM will grow rapidly, accounting for over 30 percent of the total market by 2020.
Ericsson says the IP market will reach US $15 billion and optical networking $10 billion in 2014. Jan Häglund, vice president, head of IP and broadband at Ericsson, says the two markets are not independent and that IP-over-WDM will grow rapidly, accounting for over 30 percent of the total market by 2020.
Ciena's motivation for the deal is somewhat different.
"We are focussed on packet optical convergence - Layer 2 down to Layer 0 - creating a scalable, cost effective WAN infrastructure for service providers," said James Frodsham, Ciena’s senior vice president and chief strategy officer. "We have been looking around our core value proposition, we have been looking to expand our distribution into geographies and customers where we lack presense." The deal with Ericsson clearly addresses that, he says.
There is now more to think about. It is a very interesting time.
James Frodsham, Ciena
The company also has a different view regarding IP-over-WDM. IP routers are a vital part of the network but for cost reasons they are better used in centralised locations, interconnected using packet optical networking, said Tom Mock, senior vice president, corporate communications at Ciena.
Working with Ericsson widens the network applications Ciena can address. "But our view of the prevalence of IP-over-WDM hasn't really changed," said Mock.
Tom MockEricsson and Ciena both highlight the changes taking place in the network, namely Network Functions Virtualisation (NFV) and SDN, as another reason for the tie-up.
NFV is turning telecom functions that previously required dedicated platforms into software that is virtualised and executed on servers. NFV promises to bring to telecom the benefits of IT and cloud computing, enabling operators to introduce services more quickly and scale them according to demand.
SDN, meanwhile, not only oversees such virtualised services, but also the network layers over which they run. This is where IP-over-WDM plays a role and why the two companies are working to develop Transport SDN.
It also gives us exposure to the Evolved Packet Core that is going into new wireless installations
Ciena's optical infrastructure and Ericsson's service-provider SDN and IP portfolio will result in a competitive solution, said Ericsson. "Combining the two network layers, and jointly making sure that the control protocol optimises the traffic network, will lead to CapEx and OpEx savings," said Ericsson's Häglund, in a company webcast announcing the deal.
Other benefits of the agreement include growing Ciena's relationships with services providers, especially in wireless. "It also gives us exposure to the Evolved Packet Core that is going into new wireless installations," said Mock.
Ciena also highlights Ericsson's strengths in operations and business support systems (OSS/ BSS). Ciena says the transition to SDN will be gradual. "That evolution is going to have to take into account OSS/ BSS technologies and having a partner that is strong in that area will help us both," said Mock.
Ciena believes more such industry collaboration should be expected. "We see that with programs like AT&T's Domain 2.0 Program, such thinking is also happening in the marketplace," said Mock. For the Supplier Domain 2.0 Program, AT&T is selecting vendors to provide a modern, cloud-based architecture that includes NFV and SDN technologies.
The collaboration between Ciena and Ericsson should boost their position as possible Domain 2.0 suppliers. "Both of us are suppliers under AT&T's current domain program, and as with any relationship, incumbency has advantages" said Mock. "The fact that we are beginning to collaborate on SDN-oriented applications ought to help."
Industry collaboration between telecom vendors and IT equipment providers will also likely increase.
"The data centre is a very important piece of real-estate in the future infrastructure," said Frodsham. The data centre hosts the storage and servers that manage the bulk of applications that pass across the network. Greater collaboration will be needed between telco and IT vendors to optimise how the data centre interacts with the WAN.
"There is now more to think about," said Frodsham. "It is a very interesting time."
ClariPhy samples a 200 Gigabit coherent DSP-ASIC
The CL20010 is the first of ClariPhy's LightSpeed-II family of coherent digital signal processing ASICs (DSP-ASICs), manufactured using a 28nm CMOS process. "We believe it is the first 28nm standard product, and leaps ahead of the current generation [DSP-ASIC] devices," says Paul Voois, co-founder and chief strategy officer at ClariPhy.
Paul Voois
ClariPhy has been shipping its 40 Gigabit coherent CL4010 LightSpeed chip since September 2011. Customers using the device include optical module makers Oclaro, NEC and JDSU. "We continue to go into new deployments but it is true that the 40 Gig market is not growing like the 100 Gig market," says Voois.
With the CL20010, Clariphy now joins NTT Electronics (NEL) as a merchant supplier of high-speed coherent silicon. Clariphy has said that the LightSpeed-II devices will address metro, long-haul and submarine.
No longer do the integrators need to buy a separate transmit multiplexer chip
Using an advanced 28nm CMOS process enables greater on-chip integration. The CL20010 includes the transmit and receive DSPs, soft-decision forward error correction, and mixed signal analogue-to-digital and digital-to-analogue converters. "No longer do the integrators need to buy a separate transmit multiplexer chip," says Voois.
The LightSpeed-II silicon also features an on-chip Optical Transport Network (OTN) framer/ mapper and a general-purpose processor. The general purpose processor enables the chip to be more network aware - for example, the state of a link - and support software-defined networking (SDN) in the WAN.
The LightSpeed-II ICs support three modulation schemes - polarisation-multiplexed, bipolar phase-shift keying (PM-BPSK), quadrature phase-shift keying (PM-QPSK) and 16-quadrature amplitude modulation (PM-16-QAM). Using PM-16-QAM, the CL20010 can support 200 Gigabit traffic. "I believe that is also a first for merchant silicon," says Voois.
Having an on-chip framer enables the transmission of two 100 Gigabit clients signals as a 200 Gigabit OTN signal. In turn, combining two CL20010 devices enables a 400 Gig flexible-grid super-channel to be transmitted. The on-chip transmit DSP enables the CL20010 to support flexible grid, with the dual carrier 400 Gigabit super-channel occupying 75GHz rather than 100GHz. The CL20010 can achieve a reach of 3,500km at 100 Gig, and over 600km at 200 and 400 Gig.
ClariPhy has not announced the power consumption of its chips but says that it is also targeting the metro pluggable market. Given that a CFP coherent module consumes up to 32W and that the optics alone consume 12W, a LightSpeed-II metro DSP-ASIC will likely consume 18-20W.
Merchant market
Many of the leading optical transport equipment makers, such as Alcatel-Lucent, Ciena, Cisco Systems, Huawei and Infinera, use their own coherent DSP-ASICs. More recently, Acacia Communications announced a CFP 100 Gig coherent pluggable module that uses its internally developed DSP-ASIC.
Some of the OEMs will continue to develop internal technology but even they can't cover all possible applications
ClariPhy says that despite the bulk of the 100 Gigabit coherent ports shipped use internally developed designs, there are signs that the market is moving towards adopting merchant silicon. "It doesn't happen all at once," says Voois. "Some of the OEMs will continue to develop internal technology but even they can't cover all possible applications."
He cites coherent silicon for metro networks as an example. Equipment makers are focussed on DSP-ASIC designs that satisfy the most demanding, ultra-long-haul network applications. But such high-performance, high-power chips are not suited for the more cost-conscious, low-power and compact metro requirements.
"Our committed customer base includes a nice spectrum of applications and integration types: OEMs and module vendors; metro, long haul and submarine," says Voois.
General availability of the CL20010 is expected later this year. The company will also be demonstrating the device at OFC 2014.
Coriant adds optical control to SDN framework
Coriant's CTO, Uwe Fischer, explains its Intelligent Optical Control and how the system will complement Transport SDN.
"You either master all that complexity at once, or you find the right entry point and provide value for each concrete challenge, and extend step-by-step from there"
Uwe Fischer, CTO of Coriant
Coriant has deployed a networking framework that it says will comply with Transport SDN, the software-defined networking (SDN) implementation for the wide area network (WAN).
The company's Intelligent Optical Control system is already deployed with one large North American operator while Coriant is working to install the system with other Tier 1 customers.
Work to extend SDN technology beyond the data centre to work across operators' transport networks has just begun. The Open Networking Foundation (ONF), for example, has established an Optical Transport Working Group to define the extensions needed to enable SDN control of the transport layer and not just packet.
"SDN and optical networking go together nicely; they are not decoupled but make up an end-to-end overall framework," says Uwe Fischer, CTO at Coriant.
The Intelligent Optical Control is designed to tackle immediate networking issues as Transport SDN is developed. Coriant says its system complies with the ONF's three networking layer SDN model. The top, application layer interfaces with the middle, control layer. And it is at the control layer where the SDN controller oversees the network elements found in the third, infrastructure layer.
Intelligent Optical Control adds two other components to the model. An extra intelligence component in the control layer that sits between the SDN controller and the infrastructure layer. This intelligence is designed to exploit the intricacies of the optical layer.
Coriant has also added an application at the topmost layer to automate operational procedures. "SDN at the application layer is centered around service creation," says Fischer. "We see a complete set of other applications which automate operational workflows."
Optical intelligence
One key benefit of SDN is the central view it has of the network and its resources. Such centralised control works well in the data centre and packet networking. Operators' networks are more complex, however, housing multiple vendors' equipment and multiple networking layers and protocols.
The ONF's Optical Transport Working Group is investigating two approaches - direct and abstract models - to enable the OpenFlow standard to extend its control across all the transport layers.
With the direct model, an SDN controller will talk to each network element, controlling its forwarding behaviour and port characteristics. The abstract model, in contrast, will enable the controller to talk to a network element or an intermediate controller or 'mediation'. This mediation performs a translator role, enacting requests from the SDN controller.
The direct model interests certain ONF members due to its potential of reduce the cost of networking equipment by moving much of the software from each element to the SDN controller. The abstract model, in contrast, has the benefit of limiting how much the controller needs to be exposed to the underlying network's details.
Coriant says it has yet to form a view as to the benefits of the direct and abstract ONF models. That said, Fischer does not see any mechanisms being discussed in the ONF that will fully exploit the potential of the photonic network. Accordingly, Coriant has added its own intelligence that sits between the SDN controller and the photonic layer.
“We fully comply with the approach of an SDN controller, however, we put another layer in between the control layer and the infrastructure layer,” says Fischer. “We consider it a part of the control layer, but adding the planning and routing intelligence to leverage the full performance of the infrastructure layer underneath."
Fischer says there is a role for abstraction at the photonic layer but perhaps only for metro networks. "We currently don't think this will really extend to the wide area photonic layer," he says.
"The added intelligence can leverage the full performance of the WDM network because it knows all the planning rules in detail," says Fischer. It does multi-layer optimisation across the transport layers. Coriant has added the intelligence because it does not think the transport-network-specific aspects can be centralised in a generic way.
Automated operations
Coriant's Intelligent Optical Controller also adds an application to automate operational procedures. Fischer cites how the application layer component benefits the workflow when a service is activated in the network.
With each service request, the Intelligent Optical Control details whether the new service can be squeezed onto existing infrastructure and details the service performance parameters to be expected, such as latency and the guaranteed bandwidth. "The operator can immediately judge the service level they would get," says Fischer.
Another planning mode supports the adding of equipment at the infrastructure layer. This enables a comparison to be made as to how the service level would improve with extra equipment in place.
If the operator can justify that business case for new hardware, the workflow is then automated. The tool creates the bill of materials, the electronic order, and the configuration and planning data needed to implement the hardware in the network.
Coriant says equipment and services can be time-tagged. If an engineer is known to be visiting a site once the hardware becomes available, the card can be pre-assigned and automatically used once it is plugged in. "There is a full consistency as to how the hardware is managed and optimised towards service creation," says Fischer.
Coriant is working with its major customers to create a testbed to demonstrate an SDN implementation of IP-over-DWDM. "It will involve interworking with third-party routers, and using SDN controllers to control the packet part of the network with Openflow and other mechanisms, and then connected to the Intelligent Optical Controller."
The goal is to demonstrate that Coriant's approach complies with this use case while better exploiting the optical network's capabilities.
Fischer says optical networking is moving to a new phase as transmission speeds move beyond 100 Gigabit.
"We are entering an interesting phase as capacity and reach hit the limits of practical networks," he says. "This means we are talking about flexible modulation formats and variously composed super-channels for 400 Gigabit and 1 Terabit."
In effect, a virtualisation of bandwidth is taking place at the photonic layer. "This fits nicely into the SDN principle as on the one hand it virtualises capacity, which very much fits in the model of virtualising infrastructure."
But it also brings challenges.
"There is currently not a good practical means to manage such flexible capacity at the photonic layer," says Fischer. This, says Coriant, it what its customers are saying. It also explains Coriant's decision to add the optical controller. "You either master all that complexity at once, or you find the right entry point and provide value for each concrete challenge, and extend step-by-step from there," says Fischer.
OIF defines carrier requirements for SDN
The Optical Internetworking Forum (OIF) has achieved its first milestone in defining the carrier requirements for software-defined networking (SDN).
The orchestration layer will coordinate the data centre and transport network activities and give easy access to new applications
Hans-Martin Foisel, OIF
The OIF's Carrier Working Group has begun the next stage, a framework document, to identify missing functionalities required to fulfill the carriers' SDN requirements. "The framework document should define the gaps we have to bridge with new specifications," says Hans-Martin Foisel of Deutsche Telekom, and chair of the OIF working group.
There are three main reasons why operators are interested in SDN, says Foisel. SDN offers a way for carriers to optimise their networks more comprehensively than before; not just the network but also processing and storage within the data centre.
"IP-based services and networks are making intensive use of applications and functionalities residing in the data centre - they are determining our traffic matrix," says Foisel. The data centre and transport network need to be coordinated and SDN can determine how best to distribute processing, storage and networking functionality, he says.
SDN also promises to simplify operators' operational support systems (OSS) software, and separate the network's management, control and data planes to achieve new efficiencies.
SDN architecture
The OIF's focus is on Transport SDN, involving the management, control and data plane layers of the network. Also included is an orchestration layer that will sit above the data centre and transport network, overseeing the two domains. Applications then reside on top of the orchestration layer, communicating with it and the underlying infrastructure via a programmable interface.
"Aligning the thinking among different people is quite an educational exercise, and we will have to get to a new understanding"
"The orchestration layer will coordinate the data centre and transport network activities and give, northbound, easy access to new applications," says Foisel.
A key SDN concept is programmability and application awareness, he says. The orchestration layer will require specified interfaces to ease the adding of applications independent of whether they impact the data centre, transport network or both.
Foisel says the OIF work has already highlighted the breadth of vision within the industry regarding how SDN should look. "Aligning the thinking among different people is quite an educational exercise, and we will have to get to a new understanding," he says.
Having equipment prototypes is also helping in understanding SDN. "Implementations that show part of this big picture - it is doable, it is working and how it is working - is quite helpful," says Foisel.
The OIF Carrier Working Group is working closely with the Open Networking Foundation's (ONF) Optical Transport Working Group to ensure that the two group are aligned. The ONF's Optical Transport Group is developing optical extensions to the OpenFlow standard.