Sent:Thursday, June 19, 1997 10:37 AM
Terabit per Second Switching
The DARPA Broadband Information Technology (BIT) has pioneered much of today’s wavelength-division-multiplexing (WDM) effort. WDM is a way of multiplexing a large number of wavelength channels in a single fiber and it is a very effective way of increasing the bandwidth without resorting to laying additional fibers. Industry today is rapidly deploying WDM in their long distance backbone network, but the switching of terabit per second (Tb/s) remains a major obstacle. Switching and transporting at this speed can move the whole content of the Library of Congress in 14 seconds. Recently, the MIT Lincoln Laboratory, in collaboration with Lucent Laboratories and AT&T, demonstrated the first Tb/s experiment. The switch, a silicon dioxide waveguide structure, consists of 8 input and output ports. The switching function is similar to a phase array radar which uses phase cancellation to select the useful channel. Each input port is connected to a 14-channel tunable laser and each channel is modulated at 10 Gb/s, thus resulting in a 140 Gb/s per input port. The total input to the switch is therefore 1.12 Tb/s. Each color channel was successfully routed to the appropriate output port with minimum degradation. The switch is not fully dynamically reconfigurable yet and research is underway to achieve this capability. (PM-B.Hui)(Not Sensitive)
All-Optical Network Security
Recent rapid advances of all-optical networking technologies have made networks in the tens of gigabit per second (Gb/s) range a reality. The DARPA Broadband Information Technology (BIT) program has pioneered much of these research. The extremely high performance of these networks has opened up a totally new challenge to their security protection. For example, the entire Encyclopedia Britannica can be transmitted in a fraction of a second but the conventional fault recovery software used by the industry takes about two seconds to execute, so a service interruption in these ultra fast networks could mean a total loss of the file being transferred. Recently the MIT Lincoln Laboratory has made some very impressive advances in this important area. A new automatic protection switching algorithm was invented that allows the network to recover from attacks in a time scale limited by the hardwares only. Since the optical switches can operate in nanosecond, so the network is also protected in the similar time scale. Basically the algorithm creates "logical trees" very quickly in the network to bypass the endanger node or nodes under attacked.
This approach is the first to provide protection switching with multicast trees over arbitrary reconfigurable networks, and it provides a much greater routing flexibility than the existing industry standards. Because this algorithm can adapt to any reconfigurable network, it has a wide range of applications for existing and emerging commercial networks. Research is underway to examine protections against correlated jamming and other forms of intrusion against optical networks. (PM - B. Hui) (Not Sensitive)
Demonstration of a National Scale, 20 Gigabit per Second All-Optical
One of the main objectives of the DARPA Broadband Information Technology (BIT) Program is to demonstrate the feasibility of a national scale, high capacity backbone network using optical wavelength-division-multiplexing (WDM) technologies. WDM is a new multiplexing technique which allows a single fiber to carry multiple wavelength channels. This approach is especially powerful to instantaneously increase the network capacity without resorting to laying additional fibers. A successfully national scale demonstration would entail the collaboration of three distinct sectors - local exchange carrier (LEC), long distance carrier (LD), and cross-connect (X-C) gateway providers for client signal transport and network management. Recently the MONET consortium, one of the BIT projects, which is composed of Bellcore, Lucent Technologies, AT&T, Bell Atlantic, Bell South, South Western Bell and Pacific Bell, successfully designed and interconnected three optical network testbeds in New Jersey - the LEC testbed by Bellcore at Red Bank, the LD testbed by AT&T/Lucent Technologies at Crawford Hill Lab, Holmdel, and the X-C testbed by Lucent Technologies at Holmdel, to carry out transport and switching experiments in an environment which simulates a national scale network in terms of optical fiber distance and system complexity. All the network elements: laser array transmitters, receivers, switches, were designed and built by the MONET members. The WDM network management and control softwares were also ground breaking technologies. The NJ area network is an ambitious task which not only demonstrates the feasibility of an optically reconfigurable network but also positions MONET members and DoD agencies to identify and resolve both optical transport layer performance and network control and management issues. An 8-wavelength network transport and reconfiguration experiment involved two-way connections being set up across the two domains (LEC and LD) and transport of multi-format (analog and digital) and multi-bit-rate signals (155 Mb/s and 2.5 Gb/s) have been demonstrated. The client signal integrity was verified over the longest path (2290 km) in the network. Further effort are underway to refine the system requirements and to improve fiber and system management. (PM-B. Hui)(Not Sensitive)