JOHN WILLIAMSON VIRTUAL NETWORKS
sits unused for most of the time. “But with an OCS intraDC interconnect, these PODs can be more heavily loaded and, when the peak time comes, the interconnect can be used to access overflow resources from another POD. SDN can watch and manage this whole process,” he said. Nor are PODs exactly a niche opportunity. Mordor Intelligence estimates that modular data centre market was worth $8.78 billion in 2015 and forecasts it to grow to $33.24 billion by 2020, with a CAGR of 30.51% over the forecast period. Optical switching additionally chimes well with the ever increasing overall need for higher network speeds and bandwidths. Bennett observes that optical switches work best, and o er the best economics, when data rates of the services being supported approach the “sweet spot” of the wavelength data rate. If service data rates are lower than wavelength data rates then electronics are required to multiplex up the signals. “This implies that optical switches sit at the top of the data centre switching hierarchy, operating at the highest rates and delivering switching capability at the lowest cost per bit,” concludes Bennett. ECONOMY WITH VERSATILITY OCS technology is becoming more versatile and more a ordable. Its versatility can encompass the virtualisation of fibre layer connectivity to provide scalability reaching tens of thousands of endpoints, use in inter-DC networking for physical line protection and also for low cost fixed-grid CDC ROADM deployments, and DC service protection and legal intercept operation. “OCS is becoming increasingly more economical to deploy compared with conventional Layer 2/3 OEO switches as line rates continue to rise beyond 100G,” said Parsons. According to a 2017 report from Occams Business Research / Research and Markets, the total global optical switch market, which was valued at $4.52 billion in the year 2016, could climb to $13.42 billion by 2023. As virtualisation and optical switching increase their network footprints, a new level of intensified automation is being developed and commercialised for optical networks in systems such as Ciena’s Liquid Spectrum and Infinera’s Instant Network. As described by Bennett, Cognitive Networking has three basic ingredients. Network elements that are aware of tra c levels and congestion is one. A planning system that can take data from the network elements, and plan around the problem the network elements are experiencing, is the second. The third is an underlying network infrastructure that is capable of being programmed and changed by the planning system. “This is a feedback loop, and the network becomes self-aware in terms of capacity planning,” concluded Bennett.
Production of fibre optic systems at Huber+Suhner Polatis’s facility in Herisau, Switzerland.
These and other types of deployments are promoted by a number of synergies between optical switching and virtualisation. For example, in the data centre case, the former can enable the latter to better realise its potential. According to Altstaetter, virtualisation is inherently limited when constrained by the physical layer, because there are still fibre-optic cables that bind network elements together. But when all of the network elements are connected to a low-latency Optical Circuit Switch (OCS), they can be switched to any other device attached to the OCS. “This provides the ability, via SDN, to compose network resources on demand by interconnecting any connected device together,” he said. “This gives the network manager the ability to build a single, uniform DC/DCI infrastructure that can meet the demand for all services and customer classes.” FURTHER POTENTIAL Related to this is the potential to further optimise and improve the utilisation of compute resources. This is perhaps seen most graphically in the case of prefabricated, modular, containerised Performance Optimised Datacenters (PODs), also known as modular data centres. Because these systems are self-contained, they must be configured for peak utilisation, even when they will be operating at a much lower average utilisation during most of the time. Altstaetter says that some data centre managers have told Calient Technologies that up to 60% of the capacity of a POD
over-year growth. Looking forward, ACG projects optical DCI revenue to grow at a 20.6% CAGR 2016 to 2021. Data centres are also pioneers of virtualisation, with NFV already well established in many of these facilities. NFV enables established Communications Service Providers to o er virtualised network services such as firewalls, deep packet inspection, VPN servers, routers, LANs and load balancers that are implemented in commodity compute rather than bespoke discrete hardware elements. “The principles of disaggregation within the datacentre are now gaining acceptance,” said Enrico. “This leads to significantly more e cient consumption of traditional DC resources: compute, memory and acceleration hardware.” SWITCHING ON In both wide area and data centre networks, optical switching has become an important part of the virtualisation story. “All-optical switching has evolved over the past decade from an exotic technology used in niche applications to one that has now gained widespread acceptance as a robust and reliable tool to automate fibre layer management and increase service velocity,” added Enrico. For Polatis examples of key optical switch deployments in production networks are: wavelength service protection in inter-DC enterprise networks; client-side provisioning in long- haul systems; remote reconfiguration of broadcast video networks; and QoS monitoring of mobile backhaul tra c.
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ISSUE 9 | Q2 2017
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