Alcatel-Lucent has enhanced the optical performance of its 100 Gigabit technology with the launch of its extended reach (100G XR) line card. Extending the reach of 100 Gigabit systems helps makes the technology more attractive when compared to existing 40 Gigabit optical transport.
"We have built some rather large [data centre to data centre] networks with spans larger that 1,000km in totality"
Sam Bucci, Alcatel-Lucent
Used with the Alcatel-Lucent 1830 Photonic Service Switch, the line card improves optical transmission performance by 30% by fine-tuning the algorithm that runs on its coherent receiver ASIC. The system vendor says the typical optical reach extends to 2,000km.
When Alcatel-Lucent first announced its 100 Gigabit technology in June 2010, it claimed a reach of 1,500-2,000km. Now this upper reach limit is met for most networking scenarios with the extended reach performance.
"By announcing the extended reach, Alcatel-Lucent is able to highlight the 2,000km reach as well as draw attention to the fact that it has many deployments already, and that some of those customers are using 100 Gig in 1,000km+ applications," says Sterling Perrin, senior analyst at Heavy Reading.
Market research firm Ovum views the 100G XR announcement as a specific evolutionary improvement.
"But it is significant in that it makes the case for 100 Gig versus 40 Gig more attractive for terrestrial longer-reach applications," says Dana Cooperson, network infrastructure practice leader at Ovum. “The higher the performance vendors can make 100 Gig for more demanding applications - bad fiber, ultra long-haul and ultimately submarine - the quicker it will eclipse 40 Gig.” That said, Ovum does not expect 40 Gig to be eclipsed anytime soon.
100G XR
The line card's improved optical performance equates to transmission across longer fibre spans before optical regeneration is required. This, says the vendor, saves on equipment cost, power and space.
More complex network topologies can also be implemented such as mesh networks where the signal can encounter varying-length paths based on differing fibre types as well as multiple ROADM stages. Alcatel-Lucent says it has implemented a 1,700km link with 20 amplifiers and seven ROADM stages without the need for signal regeneration.
The improved optical performance of the 100G XR has been achieved without changing the line card's hardware. The card uses the same analogue-to-digital converter, digital signal processor (DSP) ASIC and the same forward error correction scheme used for its existing 100 Gigabit line card.
What has changed is the dispersion compensation algorithm that runs on the DSP, making use of the experience Alcatel-Lucent has gained from existing 100 Gigabit deployments.
"We can tune various parameters, such as power and the way it [the algorithm] deals with impairments," says Sam Bucci, vice president, terrestrial portfolio management at Alcatel-Lucent. In particular the 100G XR has increased tolerance to polarisation mode dispersion and non-linear impairments.
Cooperson says Alcatel-Lucent has adjusted the receiver ASIC performance after 'mining' data from coherent deployments, something the company is used to doing with its wireless networks. She says Alcatel-Lucent has also worked closely with component vendors to achieve the improved performance.
Perrin points out that Alcatel-Lucent's 100 Gig design uses a single laser while Ciena's system is dual laser. "Alcatel-Lucent is saying that over an identical plant the two-laser approach has no distance advantages over the one laser approach," he says. However, other system vendors have announced distances at and beyond 2,000km. "So Alcatel-Lucent's enhanced system is not record-setting," says Perrin.
100 Gigabit Market
Alcatel-Lucent says it has more than 45 deployments comprising over 1,200 100 Gig lines since the launch of its 100 Gigabit system in 2010.
"It appears that Alcatel-Lucent has shipped more 100G line cards than anyone," says Cooperson. "Alcatel-Lucent has a good opportunity to make some serious 100 Gig inroads here, along with Ciena, while everyone else gears up to get their solutions to market in 2012."
Cooperson also says the 100G XR announcement dovetails nicely with Alcatel-Lucent’s recent CloudBand announcement. Indeed Bucci says that its deployments of 100 Gig include connecting data centres: "We have built some rather large [data centre to data centre] networks with spans larger that 1,000km in totality."
The 100G XR card is being tested by customers and will be generally available starting December 2011.