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Fault identification and localization problems in optical networks have become crucial. Due to network transparency and high data rates, optical networks are vulnerable to sophisticated attacks on the physical infrastructure [5], and hence require adequate fault monitoring in order to accurately identify and locate network failures. In transparent optical networks, faults may propagate to various parts of the network from the origin, and multiple alarms can be generated for a single failure. In order to reduce the number of redundant alarms, simplify fault localization, as well as lower financial investment in network monitoring equipment, fault monitor placement should be optimized for a given network. In this paper, we formulate a problem on the optimal placement of network monitoring devices and propose a solution approach. First we provide a brief summary of available physical-layer monitoring devices, after which we present a scheme for optimal monitor placement.

rdd, gokhan, jls, tkach) Q research. aft. corn, Phone: 973-360-871 2. FAX: 973-360-8050Because of recent advances and subsequent deployment of dense WDM, a new network layer (the "Optical Layer") has emerged and, therefore, SONET no longer resides at the network layer closest to the media itself. Also, SONET Rings, the primary technology to provide restoration from network failures in today's networks, tend to be capacity inefficient when compared to "mesh" topologies in networks with a high degree of connectivity and when, because of size limitations, connections are forced to route through many interconnected rings. This paper proposes an optic layer restoration method, competitive with SONET ring restoration speeds.We propose a distributed method to do restoration in mesh networks of Optical Cross-Connects (OXCs) with the target of achieving ring-competitive worst-case restoration times. This method assumes a simple fault detection capability in the OXC. In particular, it assumes that the network consists of high speed connections (signals, e.g., ) that route over a mesh of OXCs. Fault detection is done only at the endpoints of where the connection enters (i.e., addldrops from) the OXC-mesh network and thus the addldrop card may be the only component that is aware of the details of its constituent signal. This approach is especially adapted to OXC cross-connect fabrics that are fully optic in nature, i.e., have no electronic signal performance analysis or fault detection capabilities, except at the add/drop ports.The restoration path i s stored for each connection at one of the endpoints of the connection. Because

A novel device for tunable optical microwave generation is presented. The capability to tune the microwave frequency as well as the locking characteristics of the developed device are experimentally investigated

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