This paper reviews the work performed under the European ESPRIT project DO/spl I.bar/ALL (Digital OpticAL Logic modules) spanning from advanced devices (semiconductor optical amplifiers) to all-optical modules (laser sources and gates) and from optical signal processing subsystems (packet clock recovery, optical write/store memory, and linear feedback shift register) to their integration in the application level for the demonstration of nontrivial logic functionality (all-optical bit-error-rate tester and a 2/spl times/2 exchange-bypass switch). The successful accomplishment of the project's goals has opened the road for the implementation of more complex ultra-high-speed all-optical signal processing circuits that are key elements for the realization of all-optical packet switching networks.

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All-optical signal Processing and applications within the esprit project DO/spl I.bar/ALL

Optical networking poses a number challenges for Generalized Multi-
Protocol Label Switching (GMPLS). Fundamentally, optical technology is
an analog rather than digital technology whereby the optical layer is
lowest in the transport hierarchy and hence has an intimate
relationship with the physical geography of the network. This
contribution surveys some of the aspects of optical networks that
impact routing and identifies possible GMPLS responses for each: (1)
Constraints arising from the design of new software controllable
network elements, (2) Constraints in a single all-optical domain
without wavelength conversion, (3) Complications arising in more
complex networks incorporating both all-optical and opaque
architectures, and (4) Impacts of diversity constraints. This memo
provides information for the Internet community.

Impairments and Other Constraints on Optical Layer Routing

Given the ever increasing demand for network bandwidth, and the phenomenal advances in optical wavelength division multiplexing (WDM) networking technologies, a major component of the next generation Internet will be an Internet protocol (IP)-based optical WDM network. As IP over WDM networking technologies mature, a number of important architectural, management and control issues have surfaced. These issues need to be addressed before a true next generation optical Internet can emerge. We enumerate some of the key architectural, management and control issues and discuss corresponding approaches and advances made toward addressing these issues. We first review the different IP/WDM networking architectural models and their tradeoffs. We outline and discuss several management and control issues and corresponding approaches related to the configuration, fault, and performance management of IP over dynamic WDM networks. We present an analysis and supporting simulation results demonstrating the potential benefits of dynamic IP over WDM networks. We then discuss the issues related to IP/WDM traffic engineering in more detail, and present the approach taken in the NGI SuperNet Network Control and Management Project funded by DARPA. In particular, we motivate and present an innovative integrated traffic-engineering framework for reconfigurable IP/WDM networks. It builds on the strength of multiprotocol label switching for fine-grain IP load balancing, and on the strength of reconfigurable WDM networking for reducing the IP network's weighted-hop-distance, and for expanding the bottleneck bandwidth.

Advances in the management and control of optical Internet

In this letter, we demonstrate an optically addressable 2 /spl times/ 2 exchange-bypass switch operating with 10-Gb/s data packets. Switching is achieved at the bit level using an ultrafast nonlinear interferometer gate with two input data signals and a single control signal. The bit error rate of the switch in a static configuration was estimated to be 10/sup -11/ using synchronous digital hierarchy 64 data frames.

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Optically addressable 2 x 2 exchange/bypass packet switch

We proposed a simple method to handle IP-layer traffic surges by rapidly augmenting IP-layer link capacity over a rapidly reconfigurable optical cross-connect layer. We established both the need for this approach as well as its effectiveness by analyzing the statistical properties of actual traffic surges in a large ISP network.

Handling IP traffic surges via optical layer reconfiguration

With the Internet protocol (IP) being the dominant protocol for new network services, there is increasing pressure to optimize the network infrastructure and protocols for IP traffic. We have designed a network architecture where each node integrates a router and an optical layer cross connect to create a router optimized for the optical Internet. IP is responsible for all networking functions including network optimality and packet and optical resource management, but delegates transmission work to the optical layer, exploiting the capacity of the optical layer cross-connects. While all control and signaling uses IP, the optical lightpaths may carry arbitrary traffic, and so the control applies as well to non-IP traffic.

A. Greenberg

Papers

Smart routers-simple optics: an architecture for the optical Internet