The Optical Internetworking Forum (OIF) today announced its members have approved an Implementation Agreement (IA) that enables carriers to deploy 10gbps fiber-optic links at greater distances. The new IA ensures interoperability of vendor equipment that uses alternate signaling technologies to extend 10gbps links to distances of 120km, up from the traditional long-reach distance of 80km.
“This agreement is timely because several network equipment manufacturers have already implemented alternate signaling technologies such as duo-binary transmission or chirp managed lasers within their products,” said Karl Gass, an engineer with Sandia National Laboratories and the OIF’s Physical Layer Users Working Group chair. “Standardizing the testing of this functionality supports true interoperability between the systems offered by different network equipment manufacturers.”
There is enough leeway in the ITU specification that both the transmitter and receiver can comply with the standard, but not work together, said Gass. “That’s the area we have tried to fill.”
The OIF technical committee worked with the ITU to establish a new application code for G.959 VR (145km/2400ps/nm) based on alternate modulation techniques combined with a pre-amplified NRZ receiver.
The application code enables carriers to upgrade 2.5gbps links to 10gbps without additional equipment, such as repeaters and regenerators that compensate for the distance limitations of 10gbps signals. “The [2.5gbps] signal is slow enough so it’s not as distorted by the long distance,” said Gass. “Whereas with 10gbps links, because you are modulating faster, you have less margin for error for distortion over that link. … The catch is they can’t upgrade some of the links without changing the spacing for the equipment.”
With the new application code, service providers can upgrade to a 10gbps network with 50 percent less equipment than using previous methods.
The ITU specification and the interoperability of devices was demonstrated at the OFC/NFOEC trade event in March.
The IA is intended for use by transponder vendors and carriers evaluating transponders for use in networks.
OIF www.oiforum.com
