Level 3 Upgrades Capacity with Digital Optical System

Wholesaler Level 3 Communications Inc. announced it will upgrade the capacity of its optical network in the United States and Europe using a new digital optical networking system based on photonic integrated circuits that rolled out last spring by Infinera Communications.

Level 3 is the first major carrier in the United States to deploy the one-of-a-kind system. German carrier freenet selected the system the DTN system earlier in the year.

Accordingly, Level 3 CTO Jack Waters says the deployment underscores the carriers commitment to technological leadership. He expects it to give Level 3 advantages, including faster provisioning times, increased manageability, an improved ability to turn up incremental network routes and a roadmap to new interfaces and services. “We believe these enhancements will result in an even better overall experience for our customers, who have come to expect industry-leading quality and reliability from Level 3, he says.

Level 3 plans to install Infineras DTN across a substantial portion of its 23,000-mile fiber-optic network. Randy Dunbar, senior vice president for Level 3, says the carrier plans to complete the overbuild of a majority of its North American long-haul network by the end of the year and will provision incremental growth traffic on the Infinera DTN platform as it is rolled out in the second half of 2005. No market-specific details on the U.S. rollout or a timeline for the European network upgrade were disclosed.

Dunbar says the carriers technology choice had less to do with how it works and more to do with other factors, such as manageability, ease of deployment, reliability and the ability to support new services, and, of course, cost. On the cost side, Infineras technology provides a breakthrough reduction in the cost of handling OEO conversions, which makes it less critical to move to all-optical, he says, citing the industrys prevailing direction. Relative to the other providers we evaluated, some of which were all-optical systems, Infinera was also the leader or among the leaders in reliability, new product timing and improved manageability.

Infinera DTN enables carriers to build digital optical networks, which Rick Dodd, product marketing manager for Infinera, explains combine the scalability of WDM with bandwidth management and network intelligence. The photonic integrated circuits inside the DTN actually generate WDM signals, he says. Each chip generates 10 channels of light. You can combine multiple chips together to get 20, 30, 40 channels on a single fiber. Therefore, the DTN creates the WDM layer; it does what a DWDM system does.

However, Dodd adds because the PICs also convert optical traffic to electronic traffic, bandwidth management is possible. If you want to plug an IP router with a gigabit Ethernet interface or an Ethernet switch with a gigabit Ethernet or 10GB Ethernet, digital cross connects, add-drop multiplexers all those can plug into the DTN and it will provide the grooming and the multiplexing and the protection switching across the WDM layer it creates, he says.

Since the box is digital, adding and dropping traffic also is simplified. Its simply a matter of plugging in an electronic card, says Dodd. I dont have to select a particular wavelength, make sure Ive got the right filter in place, drop that wavelength out, change the balance of power through my amplifiers. I am just going to plug in a little card and then software configure, [for example], drop channel seven and I am done. That means I can get any service whether its a gigabit Ethernet service or a SONET service or an SDH service at any port at any node.

Additionally, this makes for easier subwavelength grooming not unlike SONET than is possible with a conventional WDM system, which only handles this at the endpoints of a nailed-up circuit. Its a subtle point because the sublamdba difficulties are underappreciated, but its an important point to service providers because they deal with the pain of this on a large scale, says Dodd.

DTNs electronics also simplify performance monitoring, he says. Since at every node, I am converting all traffic from the photonic analog domain to the electronic, digital domain, I get bit error rate information basically performance information on every circuit pervasively throughout the network, he says, adding this is in contrast to inferring network performance from measures such as signal-to-noise ratio or optical received power.

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