Fibers.org, April 11, 2003
Fibers Org - The Optical Communications Source

Scalability, reliability ease IP woes

It's time to rethink the multilayered, Internet Protocol core network and move toward a simpler and more economical alternative. That's just what US systems specialist Chiaro is doing explains Tami Freeman.

Service providers have a problem - let's call it a crisis of cost - that has its origins in the complex, tiered network architectures that underpin today's Internet Protocol (IP) backbones. In the IP core, things are far from simple: routers typically interconnect through circuits provisioned across Asynchronous Transfer Mode or Frame Relay switches. These switches connect to Synchronous Digital Hierarchy/Synchronous Optical Network add-drop multiplexers, digital cross-connects and dense wavelength-division multiplexing systems. Looks like some streamlining is in order.

Enter US start-up firm Chiaro Networks, which reckons its Enstara optical IP routing platform can help carriers to cut their capital and operational expenditures by as much as 70%. How? By collapsing traditional, multilayered IP networks into a two-tiered architecture comprising an intelligent packet layer residing on an optical transport layer. The platform comes with two big selling points: a highly scalable optical switching core that can replace cascades of electrical IP routers; and guaranteed 99.999% reliability - a must-have in the carrier world.

"The number-one issue now when you talk to carriers is the need to bring more reliability to the IP network," said Ken Lewis, Chiaro's president and chief executive officer. "If they want to offer more value-added services, such as virtual private networks, gaming and streaming video, the IP networks have to be as reliable as, if not better than, the current voice network."

A question of scale
So much for the big picture, but what about the specifics - especially those unique selling points of the Chiaro box? For starters, there is Enstara's inherent scalability. Although the need for hundreds of IP ports has not emerged as expected, carriers are still looking for systems that can upgrade easily, in service, as and when required.

Lewis explained the rationale: "The previous business model involved exhausting the capacity of the old router, then replacing it with a new model offering maybe double the capacity. That's very disruptive. Carriers nowadays don't talk so much about needing hundreds of ports - although they do want the headroom - but when they put this next generation of routers into their network, they want them to stay there a long time."

Enstara's scalability is due to its all-optical, non-blocking switching core (which also offers bit-rate and protocol independence). The switching fabric is based on a technology called optical phase array (OPA), which Chiaro claims is the first to combine high-speed switching with a large port count. "As far as we know, no-one has built a switch of this scale and speed before," noted Lewis.

The OPA switching fabric employs stacks of parallel gallium-arsenide waveguides (128 waveguides per stack) that act as beam deflectors. Applying an electric field to an individual waveguide changes its refractive index and thus the speed of light propagating through it. If all of the waveguides within a stack experience the same electric field, the light travels straight through. Changing the voltage across the waveguides, however, enables the beam to be steered by 3.

Each input fiber is incident on one of these stacks, and each stack can route the light to any output fiber. The result: a non-blocking optical fabric with nanosecond switching speeds. Chiaro has already demonstrated a 64 x 64 switch and reckons the platform can scale to 128 x 128 routing at up to 16 x 40 Gbit/s wavelengths per port.
Optical connections link the OPA switching core to the router's line-cards, where all Layer 3 functions (such as header look-up and quality of service) are performed electronically. Data are converted back into optical signals just before entering the OPA fabric and the line-cards buffer the optical packets into 400-byte chunks for switching. "As we are effectively switching packets, it is necessary to switch very fast," said Lewis. "We like to say we use electronics where that's optimum and optics where that's optimum."

The Enstara router's other big selling point is reliability. "Today's routers just aren't as reliable as they need to be, so carriers buy two routers each time and dual-feed everything," said Lewis. This doubling-up leads to a significant increase in initial capital outlay. In contrast, Chiaro's platform does not need a back-up system because its proprietary STateful Assured Routing (STAR) technology guarantees "five-nines" reliability.

In the event of a hardware or software failure, conventional routers will reboot themselves to rectify the error, a process that can take up to 15 minutes. During this downtime, neighboring routers will notice the outage and reroute traffic accordingly. When the router comes back online this traffic has to be rerouted yet again. Inevitably this can cause serious disruptions in traffic flow across an optical network.

Chiaro's STAR technology, on the other hand, enables Enstara to rectify faults so quickly that nearby routers do not notice any problem. "Technically, we're maintaining all of the data as we transfer from the failed working processor to the standby processor," explained Lewis. "And we can do that so quickly and so transparently that neighboring routers don't have a clue that anything happened. This is intriguing to carriers trying to reach a five-nines architecture."

He continued: "It is interesting the way our customers perceive us. The optical switch was a great door-opener because it was innovative and they'd not heard of it before. But the conversation quickly turned to capabilities like STAR."

Think global
Chiaro's headquarters are in Richardson, Texas, yet the company appears committed to an international strategy going forward. "Europe is a strategic market for us because there are a lot of people who are still trying to build large packet-based networks," said vice-president of marketing Carey Parker. "We're trying to be part of that [because] Europe has a good chance of a faster recovery at the packet level than the US."

Despite the dire trading conditions across the telecom sector, Parker is confident of the firm's prospects. "I think 2003 will be the year when the technical decisions on which platform to deploy will be made," he said. "I believe some carriers may begin to deploy these new platforms in the second half of this year, and that this new generation of boxes will be put in place over the next two years."

In November last year, Chiaro announced Enstara's first commercial deployment in the California Institute for Telecommunications and Information Technology's OptIPuter venture. This project aims to converge computing and communications by using optical connections between multiple sites to create a distributed supercomputer. Enstara will function as the routing engine sitting between all the mainframes and storage systems. And Lewis says that's just for starters. "In the first quarter we'll announce another customer, and this will be a more traditional application of the product," he added.

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