OTN Innovation Boosts Metro 100G
Innovation in OTN switching is rapidly becoming the key enabling technology -- the glue, if you will -- that will sufficiently bring down costs to spur 100G deployment in the metro.
Put simply, it allows hybrid WDM line cards to deliver both efficiency and future-proof features (and lower the cost sufficiently to spur implementation), enables the use of existing fiber, and provides impetus for the mass, and profitable, deployment of 100G.
The need for such capabilities is evident, as the pressure on transport networks is relentless, requiring more efficient and feature-rich transport capabilities. According to its annual Visual Networking Index (VNI), Cisco Systems Inc. (Nasdaq: CSCO) expects the volume of IP traffic to triple between 2012 and 2017 to 121 exabytes per month, while Bell Labs predicts massive growth in both metro and backbone traffic. (See Bell Labs Sees 560% Boost in Metro Data Traffic and Cisco's VNI: Stone Tablet or Debating Tool?)
While 100G optical transport technologies are helping to alleviate runaway bandwidth demands, maximizing network operator service flexibility is critical, especially as demand grows for data transport networks that can support cloud services provisioned from data centers.
As a result, the signs are positive for those in the OTN food chain. Infonetics Research Inc. reports that the OTN switching sector grew 37% in 2013 to be worth $8 billion (66% of the optical networking hardware market), and predicts a 20% compound annual growth (CAGR) from 2013 to 2018.
The research firm also noted last year that 86% of respondents to a survey of network operator executives said they planned to deploy OTN switching technology, and placed an emphasis on integrating OTN switching with WDM interfaces in the same hardware platform: By 2016, 94% of respondents who plan to use OTN switching in the core want WDM interfaces integrated in the OTN switching equipment.
According to Sterling Perrin, senior analyst at Heavy Reading , "OTN–based mesh networks, coupled with optical control plane software, enable faster bandwidth provisioning when compared to static point-to-point links and ring based networks… flexible provisioning is a key requirement for transport in the cloud. In addition, switched OTN is being tightly coupled with 100G transport as the grooming technology of choice."
Carriers are struggling with the need to increase network capacity, but not by laying new costly fiber. Recent advances in optical transmission technologies are beginning to ease the challenges, with the main advances being coherent detection, 100G Forward-Error Correction (FEC) technology, and OTN switching.
Coherent detection, proven at 40G and 100G, enables 10G wavelengths, which typically comprise current DWDM transport networks, to be upgraded to 100G wavelengths without the need to trade optical reach, invest in costly fiber upgrades, or add dispersion compensation equipment. It uses the existing fiber plant that now runs 10G to carry 100G while meeting distance requirements of up to 1000km in metro and 3000km in long-haul networks.
100G FEC corrects errors introduced during signal transmission at longer distances. Two classes of FEC technology exist:
- Hard-decision FEC: PMC's Swizzle FEC Technology, for example, delivers 9.45dB gain for 7% Overhead FEC (metro class) integrated inside its DIGI-120G OTN Processor.
- Soft-decision FEC: Coherent DSP/optics ecosystems suppliers developed SD-FEC and integrated it with their DSP to achieve much longer transmission by system vendors with in-house DSP, and third-party vendors such as Acacia and ClariPHY.
OTN switching provides a cost disruption for 100G transmissions and makes 100G viable for the metro with a higher volume/shorter optical reach.
Next page: OTN in the metro