12,502 research outputs found
On the number of wavelengths and switches in all-optical networks
Caption title.Includes bibliographical references (p. 9).Supported by the Army Research Office. DAAL03-92-G-0115 Supported by NSF. NCR-9206379Richard A. Barry and Pierre A. Humblet
Multi-Granular Optical Cross-Connect: Design, Analysis, and Demonstration
A fundamental issue in all-optical switching is to offer efficient and cost-effective transport services for a wide range of bandwidth granularities. This paper presents multi-granular optical cross-connect (MG-OXC) architectures that combine slow (ms regime) and fast (ns regime) switch elements, in order to support optical circuit switching (OCS), optical burst switching (OBS), and even optical packet switching (OPS). The MG-OXC architectures are designed to provide a cost-effective approach, while offering the flexibility and reconfigurability to deal with dynamic requirements of different applications. All proposed MG-OXC designs are analyzed and compared in terms of dimensionality, flexibility/reconfigurability, and scalability. Furthermore, node level simulations are conducted to evaluate the performance of MG-OXCs under different traffic regimes. Finally, the feasibility of the proposed architectures is demonstrated on an application-aware, multi-bit-rate (10 and 40 Gbps), end-to-end OBS testbed
Optical Multicast Routing Under Light Splitter Constraints
During the past few years, we have observed the emergence of new applications
that use multicast transmission. For a multicast routing algorithm to be
applicable in optical networks, it must route data only to group members,
optimize and maintain loop-free routes, and concentrate the routes on a subset
of network links. For an all-optical switch to play the role of a branching
router, it must be equipped with a light splitter. Light splitters are
expensive equipments and therefore it will be very expensive to implement
splitters on all optical switches. Optical light splitters are only implemented
on some optical switches. That limited availability of light splitters raises a
new problem when we want to implement multicast protocols in optical network
(because usual multicast protocols make the assumption that all nodes have
branching capabilities). Another issue is the knowledge of the locations of
light splitters in the optical network. Nodes in the network should be able to
identify the locations of light splitters scattered in the optical network so
it can construct multicast trees. These problems must be resolved by
implementing a multicast routing protocol that must take into consideration
that not all nodes can be branching node. As a result, a new signaling process
must be implemented so that light paths can be created, spanning from source to
the group members
Multiclass scheduling algorithms for the DAVID metro network
AbstractâThe data and voice integration over dense wavelength-division-multiplexing (DAVID) project proposes a metro network architecture based on several wavelength-division-multiplexing (WDM) rings interconnected via a bufferless optical switch called Hub. The Hub provides a programmable interconnection among rings on the basis of the outcome of a scheduling algorithm. Nodes connected to rings groom traffic from Internet protocol routers and Ethernet switches and share ring resources. In this paper, we address the problem of designing efficient centralized scheduling algorithms for supporting multiclass traffic services in the DAVID metro network. Two traffic classes are considered: a best-effort class, and a high-priority class with bandwidth guarantees. We define the multiclass scheduling problem at the Hub considering two different node architectures: a simpler one that relies on a complete separation between transmission and reception resources (i.e., WDM channels) and a more complex one in which nodes fully share transmission and reception channels using an erasure stage to drop received packets, thereby allowing wavelength reuse. We propose both optimum and heuristic solutions, and evaluate their performance by simulation, showing that heuristic solutions exhibit a behavior very close to the optimum solution. Index TermsâData and voice integration over dense wavelength-division multiplexing (DAVID), metropolitan area network, multiclass scheduling, optical ring, wavelength-division multiplexing (WDM). I
Flexible TDMA/WDMA passive optical network: energy efficient next-generation optical access solution
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