As more and more traffic is driven into data centers, in turn pressure builds between and among data centers. This phenomenon is known as the “bandwidth amplification effect,” which essentially means that when X amount of user traffic passes into a data center, it generates many times that amount of traffic within the data center and between that data center and others. This is why there is an urgent need for more data center interconnect (DCI) bandwidth and higher line rates to support these demands.
Operators have a couple of options for meeting DCI traffic demand. One is to increase fiber count and the other is to increase the line data rate. Increasing the data rate is far more common and economical and is accomplished with new bandwidth-variable transponders. Data rate increases may seem like the obvious remedy for boosting DCI bandwidth, but this option brings consequent issues and impairments along the optical path. These issues must be corrected via ROADMs and amplifiers. Although the modulation scheme is the most important aspect to consider when increasing DCI bandwidth, several other factors come into play. Among these are dispersion compensation, error correction, link distance (reach), amplification, channel width, and spectral tilt.
My new article on Lightwave summarizes the challenges and technologies associated with growing DCI traffic through higher line rates, and discusses each of the most important factors to be considered when planning the best way forward. Moving to higher line rates for DCI is an effective and economical way to address continued DCI growth, but a variety of equipment upgrades and new techniques are needed to adequately address new optical impairments and achieve the benefits of higher line rates.