At the SC06 International Conference, held in Tampa, FL, last November, Infinera teamed with Finisar, Level3 Communications, Internet2, and the University of California at Santa Cruz (UCSC) to demonstrate what it claims was the first successful 100-Gigabit Ethernet (100GbE) transmission through a live production network.
The 100GbE traffic was transmitted over Level3’s existing DWDM network from the show site in Tampa, FL, to Houston, TX, and back-a total of 4,000 miles.
According to Level3 principal architect Joe Lawrence, Level3 today transports eight lanes of 10 Gbit/s across its network using existing link aggregation techniques, and he is quick to point out that this demonstration is far more sophisticated. “This is bundling at the MAC layer, not the link aggregation layer,” he says. “This isn’t us just simply running LAG [link aggregation] across ten 10-gig waves. We’re already doing that in our IP network. This is actually making it appear as one 100-gig single pipe.”
The University of California at Santa Cruz provided a 100GbE MAC and packet-reordering algorithm that preserves packet order as individual traffic flows are striped across multiple wavelengths. The algorithm corrects skew caused by variable latency in the optical signals, which is a shortcoming of the existing link aggregation method.
The demonstration used an Infinera-proposed implementation for bonding 10 parallel lanes of 10 Gbit/s into one logical flow. A Xilinx FPGA electrically transmitted all 10 signals to ten 10 Gbit/s XFP optical transceivers, provided by Finisar, which converted the signals into the optical domain. From there, the signals were transmitted to Infinera’s commercially available DTN Switched WDM System, where they were handed off to the Level3 network.
Lawrence admits that, at least today, such an implementation “is not necessarily economical. It’s a demo chip, but the rest of the solution is economical,” he says. “The WDM system was not changed specifically to handle this.” Nor was the existing network, which is another reason why Level3 was keen to take part in the demonstration.
Serge Melle, vice president of technical marketing and business development at Infinera, believes the demonstration will have far-reaching effects, first because it proves that a 10× jump in the Ethernet domain is technologically feasible. And second, “it’s also recognising that Ethernet as a protocol has a lot of advantages as the next scaling step-stone rather than just continuing with SONET,” he says. “There’s a lot of consensus within the industry that Ethernet interfaces have much better cost points than core IP routers with SONET interfaces.”