Mario P. Vecchi

The LAMBDANET multiwavelength network: architecture, applications, and demonstrations

A summary is presented of research conducted over the last few years concerning the LAMBDANET multiwavelength optical network. Descriptions are given of some variations, including several applications based on these architectures. Experimental results demonstrate the technological feasibility of this approach. The LAMBDANET design incorporates three basic ingredients: (1) it associates a unique optical wavelength with each transmitting node in a cluster of nodes; (2) the physical topology is that of a broadcast star; and (3) each receiving node identifies transmitting nodes based on the transmission wavelength through wavelength demultiplexing. This network design features full connectivity among the nodes, large nonblocking throughput, data format transparency, and flexible control. The LAMBDANET network is used for both point-to-point and point-to-multipoint applications. >

Using distributed topology update and preplanned configurations to achieve trunk network survivability

The authors present a new approach for trunk network survivability. This modular approach is intended for a telephone trunk network consisting of high-bandwidth fiber-optic links connected through reconfigurable digital cross-connect nodes. It works for both node and link failures. This approach comprises a distributed protocol with two parts. First, the surviving digital cross-connect nodes are caused to converge to an agreement on the topology (i.e., what is up and what is down). Second, based on the agreed topology and on a precomputed plan for that topology, the digital cross-connect nodes are reconfigured to restore as much call-carrying capacity as possible. The modularity of this approach comes from separating the problem of devising a distributed fault-tolerant protocol to determine what the failure is from the problem of designing a network reconfiguration for that failure. >

HYPASS: an optoelectronic hybrid packet switching system

An architecture is presented for an optoelectronic hybrid packet switching system (HYPASS) for the distribution of multiple-bit-rate broadband services. HYPASS is based on an input-buffered/output-controlled arbitration protocol. The internal routing and interconnection utilizes a passive optical transport network with wavelength-tunable laser transmitters and fixed wavelength receivers. The single-stage multiwavelength optical interconnect provides an internally nonblocking network for large throughput routing of the bit-serial optical signals. An internal optical control network, with fixed-wavelength trouble receivers, sends output port information to the input nodes for arbitration and control. Packet buffer storage and control processing is performed by word-parallel electronic circuitry. The characteristics and device requirements for this design are presented along with results of a performance analysis of the arbitration and control protocol. >

Fast wavelength-switching of laser transmitters and amplifiers

The authors discuss system aspects and describe experimental demonstrations of nanosecond wavelength tuning in laser diode structures. Both tunable transmitters and tunable filters are considered. The dependence of the refractive index on the carrier density in semiconductors is exploited to obtain fast wavelength tuning. Experimentally, switching times of >

A broadband optoelectronic packet switching system

A novel architecture is presented for a optoelectronic hybrid packet-switching system (HYPASS) for the distribution of multiple-bit-rate broadband services. HYPASS is based on an input-buffered/output-controlled arbitration protocol. This packet switch uses novel multiwave-length optical networks to accomplish routing and transmission of the packets. This system is specifically adapted to utilize the strengths of both optical and electronic technologies. >

An optoelectronic packet switch utilizing fast wavelength tuning

The authors present a hybrid packet-switching-system architecture called Hypass that is based on integrated electronic and optical subsystems. The design uses multiwavelength optical interconnects with rapidly tunable transmitters and receivers. Experimental feasibility studies of the required optical devices are reported. Transmitter tuning time <5 ns are demonstrated using a double-section DFB (distributed feedback) laser randomly tuned among eight channels. Receiver tuning times of approximately=1 ns are obtained using DFB optical amplifiers switched between two wavelength-multiplexed channels separated by 0.23 nm. The selection of 12-bit-long packets, switched between two wavelength-multiplexed channels, has been demonstrated, indicating that transient-response requirements for a packet-switch operating at 1.2 Gb/s can be realized with a bit error rate <10/sup -9/.<<ETX>>

A comparison of strategies for survivable network design: reconfigurable and conventional approaches

A novel approach to network survivability, based on the rapid reconfiguration of highspeed digital cross-connect systems (DCS), is compared with the conventional approach, based on 1:1 protection switching using diverse routes. Two sample networks are modeled, one ring and one mesh, and the installed first cost of the required network elements is calculated. By varying the network parameters, the sensitivity of both approaches to link length, degree of network connectivity and repeaterless span length can be quantified. While no approach consistently minimizes installed first costs, the results provide insight into the preferred range of applications for the different survivability strategies.<<ETX>>