Nokia adds 400G coherent modules across its platforms
Nokia is now shipping its 400-gigabit coherent multi-haul CFP2-DCO. The module exceeds the optical performance of 400ZR and ZR+ coherent pluggables.
Nokia’s CFP2-DCO product follows its acquisition of silicon photonics specialist, Elenion Technologies, in 2020.
Nokia has combined Elenion’s coherent optical modulator and receiver with its low-power 64-gigabaud (GBd) PSE-Vc coherent digital signal processor (DSP).
Nokia is also adding coherent pluggables across its platform portfolio.
“Not just optical transport and transponder platforms but also our IP routing portfolio as well,” says Serge Melle, director of product marketing, IP-optical networking at Nokia.
“This [amplifier and filter] allows for much better optical performance,”
“This [amplifier and filter] allows for much better optical performance,”
Melle is an optical networking industry veteran. He joined Nokia two years ago after a 15-year career at Infinera. Melle started at Pirelli in 1995 when it was developing a 4×2.5-gigabit wavelength-division multiplexing (WDM) system. In between Pirelli and Infinera, Melle was at Nortel Networks during the optical boom.
400ZR, ZR+ and the multi-haul CFP2-DCO
The CFP2-DCO’s optical performance exceeds that of the QSFP-DD and OSFP form factors implementing 400ZR and ZR+ but is inferior to line-card coherent transponders used for the most demanding optical transport applications.
The 400ZR coherent OIF standard transmits a 400-gigabit wavelength up to 120km linking equipment across data centres. Being a standard, 400ZR modules are interoperable.
The ZR+ adds additional transmission speeds – 100, 200 and 300-gigabits – and has a greater reach than ZR. ZR+ is not a standard but there is the OpenZR+ multi-source agreement (MSA).
Implementing 400ZR and ZR+ coherent modules in a QSFP-DD or OSFP module means they can be inserted in client-side optics’ ports on switches and routers.
The OIF did not specify a form factor as part of the 400ZR standard, says Melle, with the industry choosing the QSFP-DD and OSFP. But with the modules’ limited power dissipation, certain modes of the coherent DSP are turned off, curtailing the feature set and the reach compared to a CFP2-DCO module.
The modules also have physical size restrictions.
“You don’t have enough thermal budget to put an optical amplifier inside the QSFP-DD package,” says Melle. “So you are left with whatever power the DWDM laser outputs through the modulator.” This is -7dBm to -10dBm for 400ZR and ZR+ optics, he says.
The CFP2-DCO is larger such that the DSP modes of encryption, OTN client encapsulation, LLDP snooping (used to gather data about attached equipment), and remote network monitoring (RMON) can be enabled.
The CFP2-DCO can also house an optical amplifier and tunable filter. The filter reduces the out-of-band optical signal-to-noise ratio (OSNR) thereby increasing the module’s sensitivity. “This [amplifier and filter] allows for much better optical performance,” says Melle. A 400-gigabit multi-haul module has a 0dBm optical output power, typically.
The different transceiver types are shown in the table.
Nokia’s paper at the recent OFC virtual conference and exhibition detailed how its 400-gigabit multi-haul CFP2-DCO achieved a reach of 1,200km.
The paper details the transmission of 52, 400-gigabit signals, each occupying a 75GHz channel, for a total capacity of 20.8 terabits-per-second (Tbps).
Melle stresses that the demonstration was more a lab set-up than a live network where a signal goes through multiple reconfigurable optical add-drop multiplexers (ROADMs) and where amplifier stages may not be equally spaced.
That said, the CFP2-DCO’s reach in such networks is 750km, says Nokia.
IP-optical integration
Having coherent pluggables enables 400 Gigabit Ethernet (400GbE) payloads to be sent between routers over a wide area network, says Nokia.
“Given this convergence in form factor, with the QSFP-DD and ZR/ ZR+, you can now do IP-optical integration, putting coherent optics on the router without sacrificing port density or having locked-in ports,” says Melle.
Nokia is upgrading its IP and optical portfolio with coherent pluggables.
“In the routers, ZR/ ZR+, and in transponders not only the high-performance coherent optics – the [Nokia] PSE-Vs [DSP] – but also the CFP2-DCO multi-haul,” says Melle. “The 400-gigabit multi-haul is also going to be supported in our routers.”
Accordingly, Nokia has developed two sets of input-output (I/O) router cards: one supporting QSFP-DDs suited for metro-access applications, and the second using CFP2-DCO ports for metro and regional networks.
The choice of cards adds flexibility for network operators; they no longer need to have fixed CFP2-DCO slots on their router faceplates, whether they are used or not. But being physically larger, there are fewer CFP2-DCO ports than QSFP-DD ports on the I/O cards.
While the QSFP-DD MSA initially defined the module with a maximum power dissipation of 14.5W, a coherent QSFP-DD module consumes 18-20W. Dissipating the heat generated by the modules is a challenge.
Nokia’s airflow cooling is simplified by placing a module on both sides of the line card rather than stacking two CFP2-DCOs, one on top of the other.
Nokia is adding its CFP2-DCO to its 1830 optical transport portfolio. These include its PSI-M compact modular systems, the PSS transponder systems and also its PSS-x OTN switching systems.
The 400ZR/ZR+ module will be introduced with all its routing platforms this summer – the 7250 IXR, 7750 SR, 7750 SR-s, and the 7950 XRS, whereas the CFP2-DCO will be added to its 7750 and 7950 series later this year.
Nokia will source the 400ZR/ZR+ from third parties as well as from its optical networks division.
Its routers use QSFP-DD form-factor for all 400GbE ports and this is consistent for most router vendors in the industry. “Thus, our use and supply of 400ZR/ZR+ pluggable DCOs will focus on the QSFP-DD form-factor,” says Melle. However, the company says it can offer the OSFP form-factor depending on demand.
Network planning study
Nokia published a paper at OFC on the ideal coherent solution for different applications.
For metro aggregation rings with 4-5 nodes and several ROADM pass-throughs, using ZR+ modules is sufficient. Moreover, using the ZR+ avoids any loss in router port density.
For metro-regional core applications, the ZR+’s optical performance is mostly insufficient. Here, the full 400-gigabit rate can not be used but rather 300 gigabit-per-second (Gbps) or even 200Gbps to meet the reach requirements.
Using a 400-gigabit multi-haul pluggable on a router might not match the density of the QSFP-DD but it enables a full 400-gigabit line rate.
For long-haul, the CFP2-DCO’s performance is “reasonable”, says Nokia, and this is where high-performance transponders are used.
What the OFC paper argues is that there is no one-size-fits-all solution, says Melle.
800-Gigabit coherent pluggables
Traditionally, the IEEE has defined short-reach client-side optics while the OIF defines coherent standards.
“If we want this IP-optical convergence continuing in the next generation of optics, those two worlds are going to have to collaborate more closely,” says Melle.
That’s because when a form-factor MSA will be defined, it will need to accommodate the short-reach requirements and the coherent optics. If this doesn’t happen, says Melle, there is a risk of a new split occuring around the IP and optical worlds.
The next generation of coherent pluggables will also be challenging.
All the vendors got together in 2019 and said that 400ZR was just around the corner yet the modules are only appearing now, says Melle.
The next jump in pluggable coherent optics will use a symbol rate of 90-130GBd.
“That is very much the cutting-edge so it brings back the optics as a critical enabling technology, and not just optics but the packaging,” concludes Melle.
North American operators in an optical spending rethink
Optical transport spending by the North American operators dropped 13 percent year-on-year in the third quarter of 2014, according to market research firm Dell'Oro Group.
Operators are rethinking the optical vendors they buy equipment from as they consider their future networks. "Software-defined networking (SDN) and Network Functions Virtualisation (NFV) - all the futuristic next network developments, operators are considering what that entails," says Jimmy Yu, vice president of optical transport research at Dell’Oro. "Those decisions have pushed out spending."
NFV will not impact optical transport directly, says Yu, and could even benefit it with the greater signalling to central locations that it will generate. But software-defined networks will require Transport SDN. "You [as an operator] have to decide which vendors are going to commit to it [Transport SDN]," says Yu.
SDN and NFV - all the futuristic next network developments, operators are considering what that entails. Those decisions have pushed out spending
The result is that the North American tier-one operators reduced their spending in the third quarter 2014. Yu highlights AT&T which during 2013 through to mid 2014 undertook robust spending. "What we saw growing [in that period] was WDM metro equipment, and it is that spending that has dropped off in the third quarter," says Yu. For equipment vendors Ciena and Fujitsu that are part of AT&T's Domain 2.0 supplier programme, the Q3 reduced spending is unwelcome news. But Yu expects North American optical transport spending in 2015 to exceed 2014's. This, despite AT&T announcing that its capital expenditure in 2015 will dip to US $18 billion from $21 billion in 2014 now that its Project VIP network investment has peaked.
But Yu says AT&T has other developments that will require spending. "Even though AT&T may reduce spending on Project VIP, it is purchasing DirecTV and the Mexican mobile carrier, lusacell," he says. "That type of stuff needs network integration." AT&T has also committed to passing two million homes with fibre once it acquires DirecTV.
Verizon is another potential reason for 2015 optical transport growth in North America. It has a request-for-proposal for metro DWDM equipment and the only issue is when the operator will start awarding contracts. Meanwhile, each year the large internet content providers grow their optical transport spending.
Dell'Oro expects 2014 global optical transport spending to be flat, with 2015 forecast to experience three percent growth
Asia Pacific remains one of the brighter regions for optical transport in 2014. "Partly this is because China is buying a lot of DWDM long-haul equipment, with China Mobile being one of the biggest buyers of 100 Gig," says Yu. EMEA continues to under-perform and Yu expects optical transport spending to decline in 2014. "But there seems to be a lot of activity and it's just a question of when that activity turns into revenue," he says.
Dell'Oro expects 2014 global optical transport spending to be flat compared to 2013, with 2015 forecast to experience three percent growth. "That growth is dependent on Europe starting to improve," says Yu.
One area driving optical transport growth that Yu highlights is interconnected data centres. "Whether enterprises or large companies interconnecting their data centres, internet content providers distributing their networks as they add more data centres, or telecom operators wanting to jump on the bandwagon and build their own data centres to offer services; that is one of the more interesting developments," he says.
60-second interview with Michael Howard
Infonetics Research has interviewed global service providers regarding their plans for software-defined networking (SDN) and network functions virtualisation (NFV). Gazettabyte asked Michael Howard, co-founder and principal analyst, carrier networks, about Infonetics' findings.
"Data centres are simple when compared to carrier networks"
Michael Howard, Infonetics Research
What is it about SDN and NFV - technologies still in their infancy - that already convinces 86 percent of the operators to deploy the technologies in their optical transport networks?
Michael H: Operators have a universal draw to SDN and NFV for two basic reasons:
1. They want to accelerate revenue by reducing the time to new services and applications.
2. They have operational drivers, of which there are also two parts:
- Carriers expect software-defined networks to give them a single view across multiple vendor equipment, network layers and equipment types for mobile backhaul, consumer digital subscriber line (DSL), passive optical network (PON), optical transport, routers, mobile core and Ethernet access. This global view will allow them to provision, monitor and deliver service-level agreements while controlling services, virtual networks and traffic flows in an easier, more flexible and automated way.
- An additional function possible with such a global view across the multi-vendor network is that traffic can be monitored and re-distributed along pathways to make best use of the network. In this way, the network can run 'hotter' and thereby require less equipment, saving capital expenditure (CapEx).
Optical transport networks have a history of being engineered to effect predictable flows on transport arteries and backbones. Many operators have deployed, or have been experimenting with, GMPLS (Generalized Multi-Protocol Label-Switching) and vendor control planes. So it is natural for them to want to bring this industry standard method of deploying an SDN control plane over the usually multi-vendor transport network.
In our conversations - independent of our survey - we find that several operators believe the biggest bang for the SDN buck is to use SDN for single control plane over multi-layer data - router, Ethernet - and the optical transport network.
"The virtualisation of data centre networks has inspired operators who want to apply the same general principles to their oh-so-much-more complex networks"
Early use of SDN has been in the data centre. How will the technologies benefit networks more generally and optical transport in particular?
SDNs were developed initially to solve the operational problems of un-automated networks. That is to say, slow human labour-intensive network changes required by the automated hypervisor as it moves, adds and changes virtual machines across servers that may be in the same data centre or in multiple data centres.
The virtualisation of data centre networks has inspired operators who want to apply the same general principles to their oh-so-much-more complex networks. Data centres are simple when compared to carrier networks. Data centres are basically large numbers of servers connected by Ethernet LANs and virtual LANs with some router separations of the LANs connecting servers.
"It will be many years before SDNs-NFV will be deployed in major parts of a carrier network"
Service provider networks are a set of many different types of networks including consumer broadband, business virtual private networks, optical transport, access/ aggregation Ethernet and router networks, mobile core and mobile backhaul. Each of these comprises multiple layers and almost certainly involves multiple vendor equipment. This explains why operators are starting their SDN-NFV investigations with small network segments which we call 'contained domains'. It will be many years before SDNs-NFV will be deployed in major parts of a carrier network.
You mention small SDN and NFV deployments. What will these early applications look like?
Our survey respondents indicated that intra-datacentre, inter-datacentre, cloud services, and content delivery networks (CDNs) will be the first to be deployed by the end of 2014. Other areas targeted longer term are optical transport, mobile packet core, IP Multimedia Subsystem, and more.
Was there a finding that struck you as significant or surprising?
Yes. A lot of current industry buzz is about optical transport networks, making me think that we'd see SDNs deployed soon. But what we heard from operators is that optical transport networks are further out in their deployment plans. This makes sense in that the Open Networking Foundation working group for transport networks has just recently got their standardisation efforts going, which usually takes a couple of years.
You say that it will be years before large parts or a whole network will be SDN-controlled. What are the main challenges here regarding SDN and will they ever control a whole network?
As I said earlier, carrier networks are complex beasts, and they are carrying revenue-generating services that cannot be risked by deployment of a new set of technologies that make fundamental changes to the way networks operate.
A major problem yet to be resolved or even addressed much by the industry is how to add SDN control planes to the router-controlled network that uses the MPLS control plane. SDN and MPLS control planes must cooperate or be coordinated in some way since they both control the same network equipment-not an easy problem, and probably the thorniest of all challenges to deploy SDNs and NFV.
The study participants rated CDNs, IP multimedia subsystem (IMS), and virtual routers/ security gateways as the main NFV applications. At least two of these segments already use servers so just how impactful will NFV be for operators?
Many operators see that they can deploy NFV in a much simpler way than deploying control plane changes involved with SDNs.
Many network functions have already been virtualised, that is software-only versions are available, and many more are under development. But these are individual vendor developments, not done according to any industry standards. This means that NFV - network functions run on servers rather than on specialised network equipment like firewalls, intrusion prevention/ intrusion detection systems, Evolved Packet Core hardware - is already in motion.
The formalisation of NFV by the carrier-driven ETSI standards group is underway, developing recommendations and standards so that these virtualised network functions can be deployed in a standardised way.
Infonetics interviewed purchase-decision makers at 21 incumbent, competitive and independent wireless operators from EMEA (Europe, Middle East, Africa), Asia Pacific and North America that have evaluated SDN projects or plan to do so. The carriers represent over half (53 percent) of the world's telecom revenue and CapEx.