FEATURE 100G NETWORKS
more difficult to compensate. ‘We’ve cracked linear impairments like chromatic dispersion and PMD, but we need vastly different algorithms for nonlinear impairments,’ pointed out Geoff Bennett, director of technology and solutions marketing at Infinera. Until that problem is solved, it’s going to be tough to make higher-order modulation schemes practical, he says.
Further developments Using more distributed amplification schemes would help to reduce the optical peak power and nonlinear distortion. Another avenue for exploration is new optical fibres with reduced attenuation, reduced nonlinear coefficient and large effective core areas, which would enable higher launch powers to be used, and thus increase reach. Corning has argued for new transmission fibre for 400G, suggesting that cable overlay with new transmission fibre would be
RECORD BREAKERS
Optical equipment vendors declare world firsts on a fairly frequent basis, but it’s not often that one claims a Guinness World Record. In August, systems vendor Infinera and DANTE (Delivery of Advanced Network Technology to Europe), an operator of advanced networks for research and education, set a Guinness World Record for the fastest provisioning of multi-Terabit optical capacity. The record was set using
Infinera’s DTN-X optical transport platform, deployed on the pan-European
research network GÉANT across a long-distance link from Vancis in Amsterdam, The Netherlands, to GlobalConnect in Hamburg, Germany. The total time from the insertion of the first 500G superchannel line card to the activation of the 100 Gigabit Ethernet service was 19 minutes and one second. Geoff Bennett, director of
technology and solutions marketing at Infinera and leader of the record- breaking team, explains how it came about. ‘We’d just completed the 2Tbps in less than 12 minutes on the
GÉANT network with DANTE, and the idea was raised that we could maybe get this rubber-stamped by the Guinness World Records (GWR) organisation. Unfortunately GWR doesn’t just rubber stamp record attempts. They actually take their role pretty seriously.’ First, Bennett had to
persuade the officials that this was a valid record, and that it would be possible for other companies to try to break it. He put together a test specification that was approved by GWR, and spoke to several customers about hosting the record attempt. Once again, DANTE
stepped up – although a different route had to be found as the one used for the original demonstration was now in service and carrying live traffic. Having already shown
This is what 8Tbps looks like: 80 channels of 100G PM-QPSK displayed on an Optical Spectrum Analyser (OSA) that shows the C-Band, which is split into two sections (red and blue). The super-channels are so densely packed that the fine detail is hardly visible, except at the peaks
that 2Tbps was possible, Infinera decided to load up the equipment to its maximum, bringing up 8Tbps of optical capacity using 16 line cards. Any Guinness World Record has to be described by a single variable, which in this case
The adjudicators of the Guinness World Record for the
fastest provisioning of multi-Terabit optical capacity: Sam Mason from Guinness World Records and Wolf Pueschner, formerly VP of Network Engineering for DTAG’s pan-European network, discuss the insertion sequence
was a provisioning rate of 26.02 Tbps per hour. That’s the figure that another organisation would need to beat in order to wrestle the record away from Infinera. ‘This is not just an
intellectual exercise that we
did,’ claimed Bennett. ‘The impact of cloud is making [bandwidth] demands bigger and lead times shorter. ‘This is genuine proof that
we can bring up large amounts of capacity in short amounts of time.’
more cost-effective than reengineering the amplifiers and amplifiers spans in the network. But if history is any guide, this is not likely to be the first choice for carriers. Infinera has side-stepped the need for
higher-order modulation schemes by sticking with 100G wavelengths, which it can build up into 500G superchannels (although Bennett points out that Infinera’s transmitter is also programmable and offers 16-QAM as an option to increase capacity on short reaches). Unlike other vendors, who build complex line cards out of multiple optical components, Infinera has based its DTN-X optical transmission system around photonic integrated circuits (PICs), with each pair (one transmit PIC, one receive PIC) containing all the optical functions for five 100-Gbps carriers. Tis removes the economic imperative to reduce the number of subcarriers, while also making it easier to scale capacity, the company claims.
@fibresystemsmag |
www.fibre-systems.com
Te days of a single modulation scheme may be
coming to an end. With high-speed transmitters supporting multiple modulation formats – and therefore multiple speeds and reaches – carriers will instead need to optimise their systems around their network requirements. While flexibility in modulation schemes is being billed as an advantage, the reality is that it is being forced upon the industry by some unyielding laws of physics. Present-day transmission speeds are also limited by the speed of the electronics, which has not kept pace with the demand for more capacity. Te migration to data rates beyond 100G will present some significant challenges, especially over long distances.l
Further reading Ciena Insights Blog: Coherent optical turns 5: Here’s how it was made
http://www.ciena.com/ connect/blog/Coherent-optical-turns-5-Heres-
how-it-was-made.html
16 FIBRE SYSTEMS Issue 1 • Autumn 2013
Infinera
Infinera
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36