Verizon Mulls the Mesh
The work surfaced in September, when researchers from Verizon and chip startup Parama Networks Inc. presented a paper at NFOEC. More recently, Parama's been making noise on its own: The company announced its technology earlier this month, and officials say a $7 million Series B funding round is on the way (see Parama Intros 'ADM on a Chip').
Verizon executives weren't available to comment, but Dean Casey, the company's former director of optical networking, says Verizon has eyed a mesh core for a couple of years.
Equipment vendors were keen on the idea, but none could build a mesh that met the 50-millisecond restoration provided by Sonet. "We stopped pursuing it for a while when we didn't get anybody to deliver us a product," says Casey, who left Verizon late last year to become an independent consultant.
Carriers have pondered meshed networks for years, hoping to overcome the inefficiencies of rings. In particular, bidirectional line-switched rings hold half their bandwidth in reserve in case of failures -- an inefficiency a mesh could overcome.
The mesh hasn't proven feasible yet, however. Besides the 50ms question, a mesh is more complicated to manage, a problem that potentially eclipses any cost savings. Rings also respond predictably after a failure, a quality that carriers cherish.
Part of the difficulty was that Verizon and others envisioned a mesh without Sonet, sending services natively across DWDM and offering protection at the wavelength level. Parama proposes to keep Sonet around but alter BLSR so that rings don't have to reserve protection bandwidth. It's similar to the philosophy preached in Resilient Packet Ring Technology (RPR), where more of a ring's bandwidth is freed up for use.
Parama's approach caught Verizon's eye. "It was all Sonet, which made them feel good," says Hemant Bheda, Parama CEO.
The companies' NFOEC paper proposes using rings in a different form, allowing them to overlap or share spans -- capabilities for which Parama has patents pending. The rings wouldn't reserve bandwidth for protection; instead, the network would respond to failures by creating new routes, cutting across multiple rings as necessary. Because paths can overlap and share spans, the new route could be built on top of active traffic.
Since there aren't any explicit protection paths, carriers could offer classes of protection -- full Sonet-like guarantees for a higher price, or best-effort recovery for a discount.
Verizon might have a chance to test-drive this kind of mesh soon. Parama got its first chips back from manufacturing nearly three months ago and says they're ready to sample.
Parama's goals for the chips go beyond the mesh network. The company aims to squash an add/drop multiplexer (ADM) into one line card, one with software-programmable ports that can be set for OC3, OC12, OC48, or Gigabit Ethernet. This would allow service providers to keep one generic line card for all those interfaces, reducing the cost of ADM systems (see Parama Intros 'ADM on a Chip').
— Craig Matsumoto, Senior Editor, Light Reading