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PAULINE RIGBY
100G makes waves in the metro
Commercial 100G deployments started in 2010 following several years of posturing, prototypes and eventually customer trials. During 2012, deployment of 100G wavelengths in core networks suddenly accelerated and that momentum has continued into 2013, according to analysts. The inexorable growth in bandwidth has created the urgency for carriers to upgrade their networks with more spectrally efficient technologies. The metro market segment typically develops a few years after the long-haul market – and becomes two to three times larger in size – as the economics of increased volumes start to tip purchasing decisions in favour of the newer technology. This adoption point seems to have been reached right on schedule with the 100G metro market becoming a reality over the last year. Some of the early adopters of metro 100G include major carriers like Verizon and Cable & Wireless Worldwide, with Verizon deciding to take its metro 100G network expansion global in 2013. In the long-haul market, 100G has been standardized around the polarization multiplexed quadrature phase-shift keying (PM-QPSK) coherent modulation format. With their superior optical performance, it’s not surprising that coherent transceivers are also attractive for the emerging 100G metro market. However, one challenge for wider adoption of 100G in the metro is that service providers are less willing to pay a premium for the performance benefits provided by coherent technology. In metro networks, price, space and power dissipation metrics carry more weight when a carrier is making a purchasing decision. And optical performance is clearly much less of an issue over the shorter distances in metro networks, which are typically up to 500 km. Daryl Inniss, leader for optical components research at Ovum, points out that 100G line card pricing has actually declined
faster than 10G did at the same stage in its life cycle. And as the market matures, the development of merchant supplier modules for 100G coherent transmission and techniques like photonic integration inside the optical modules should help to drive prices down further in the future, he says. Will this be enough to satisfy carriers? Last November Infonetics Research decided to ask 25 large service providers about their deployment plans for high- speed optical connections in both core and metro networks, asking what carriers’ expectations were for 2015. Survey respondents anticipated a surge of coherent installations: by 2015 coherent wavelengths will account for 68% of deployments in the core and 29% in the metro. When Infonetics asked about their preferred implementation of metro 100G, more carriers (40%) responded that they preferred to use the same module in the metro as in the core. Other options included a 100G coherent pluggable module optimized for metro/regional distances, non- coherent approaches such as a 4x28G direct-detect scheme or even 200G 16-QAM for the higher spectral efficiency that such a scheme would bring. Schmitt says he followed up with the carriers to try and understand their reasons for picking the options they did, and it became clear that there was still much uncertainty around their choices. One factor may be that so far only one vendor, ADVA Optical Networking, has commercially released an alternative to 100G coherent based on a direct- detection scheme, although ECI Telecom has said that it also has designs on this sector of the market (but had no commercial release at the time of writing). This approach reuses parts originally developed for 10G, and adopts the IEEE 802.3ba concept of parallel lanes, which provides a comfortable fit for some customer applications. While interest appears to be
emerging in using 200G for the metro, there are no commercial products yet and carriers may not find it easy to get their hands on parts for evaluation. This approach – currently the highest capacity on a single wavelength – could be adapted to suit the most congested metro routes. A number of vendors, such as Alcatel-Lucent, Ciena and Huawei, have demonstrated 200G 16-QAM signals, as part of a dual-carrier approach to creating 400G wavelengths. Carrier choices will also be affected by the more distributed and inhomogeneous nature of metro networks, serving many more locations and types of customer. Unlike core networks which can make a more predictable transition to all 100G wavelengths, it will be important for metro network equipment to retain flexibility, and to continue support for 10G and 40G wavelengths in addition to 100G, 200G, and whatever comes next. Whatever carriers decide, a clearer picture will emerge soon. Metro networks are seeing greater impact from traffic growth driven by end-user video; partly because bandwidth- saving technologies like caching and content delivery networks cannot be exploited closer to the consumer. According to Cisco’s Visual Network Index, metro network traffic is forecast to grow nearly twice as fast as long-haul traffic between 2012 and 2017. Daryl Inniss, leader of optical components research at Ovum, will be kicking off the “high speed optical transmission” session on Monday 23rd September at 12:10PM in the Market Focus theatre with a talk entitled “The 100G price challenge”. Other speakers in that session expressly looking at the topic of high-speed transmission in metro networks include Tellabs, Fujitsu Network Communications, ClariPhy and Acacia Communications. Pauline is a freelance technology writer and contributing editor to www.opticalconnectionsnews.com
By Pauline Rigby C an coherent 100G become economical for wide- spread deployment in metro networks, or do carriers need a lower cost option? This question has been hotly debated in the optical industry for several years now, and judging from the number of presentations on the subject at the Market Focus Forum at the ECOC Exhibition, there’s still plenty to discuss.
Metro network traffic is forecast to grow nearly twice as fast as long-haul traffic between 2012 and 2017
26 | Optical Connections 2013 | www.opticalconnectionsnews.com |
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