720 research outputs found
Benchmarking and viability assessment of optical packet switching for metro networks
Optical packet switching (OPS) has been proposed as a strong candidate for future metro networks. This paper assesses the viability of an OPS-based ring architecture as proposed within the research project DAVID (Data And Voice Integration on DWDM), funded by the European Commission through the Information Society Technologies (IST) framework. Its feasibility is discussed from a physical-layer point of view, and its limitations in size are explored. Through dimensioning studies, we show that the proposed OPS architecture is competitive with respect to alternative metropolitan area network (MAN) approaches, including synchronous digital hierarchy, resilient packet rings (RPR), and star-based Ethernet. Finally, the proposed OPS architectures are discussed from a logical performance point of view, and a high-quality scheduling algorithm to control the packet-switching operations in the rings is explained
Cross-layer design of multi-hop wireless networks
MULTI -hop wireless networks are usually defined as a collection of nodes
equipped with radio transmitters, which not only have the capability to
communicate each other in a multi-hop fashion, but also to route each othersâ data
packets. The distributed nature of such networks makes them suitable for a variety of
applications where there are no assumed reliable central entities, or controllers, and
may significantly improve the scalability issues of conventional single-hop wireless
networks.
This Ph.D. dissertation mainly investigates two aspects of the research issues
related to the efficient multi-hop wireless networks design, namely: (a) network
protocols and (b) network management, both in cross-layer design paradigms to
ensure the notion of service quality, such as quality of service (QoS) in wireless mesh
networks (WMNs) for backhaul applications and quality of information (QoI) in
wireless sensor networks (WSNs) for sensing tasks. Throughout the presentation of
this Ph.D. dissertation, different network settings are used as illustrative examples,
however the proposed algorithms, methodologies, protocols, and models are not
restricted in the considered networks, but rather have wide applicability.
First, this dissertation proposes a cross-layer design framework integrating
a distributed proportional-fair scheduler and a QoS routing algorithm, while using
WMNs as an illustrative example. The proposed approach has significant performance
gain compared with other network protocols. Second, this dissertation proposes
a generic admission control methodology for any packet network, wired and
wireless, by modeling the network as a black box, and using a generic mathematical
0. Abstract 3
function and Taylor expansion to capture the admission impact. Third, this dissertation
further enhances the previous designs by proposing a negotiation process,
to bridge the applicationsâ service quality demands and the resource management,
while using WSNs as an illustrative example. This approach allows the negotiation
among different service classes and WSN resource allocations to reach the optimal
operational status. Finally, the guarantees of the service quality are extended to
the environment of multiple, disconnected, mobile subnetworks, where the question
of how to maintain communications using dynamically controlled, unmanned data
ferries is investigated
Control Plane Hardware Design for Optical Packet Switched Data Centre Networks
Optical packet switching for intra-data centre networks is key to addressing traffic requirements. Photonic integration and wavelength division multiplexing (WDM) can overcome bandwidth limits in switching systems. A promising technology to build a nanosecond-reconfigurable photonic-integrated switch, compatible with WDM, is the semiconductor optical amplifier (SOA). SOAs are typically used as gating elements in a broadcast-and-select (B\&S) configuration, to build an optical crossbar switch. For larger-size switching, a three-stage Clos network, based on crossbar nodes, is a viable architecture. However, the design of the switch control plane, is one of the barriers to packet switching; it should run on packet timescales, which becomes increasingly challenging as line rates get higher. The scheduler, used for the allocation of switch paths, limits control clock speed. To this end, the research contribution was the design of highly parallel hardware schedulers for crossbar and Clos network switches. On a field-programmable gate array (FPGA), the minimum scheduler clock period achieved was 5.0~ns and 5.4~ns, for a 32-port crossbar and Clos switch, respectively. By using parallel path allocation modules, one per Clos node, a minimum clock period of 7.0~ns was achieved, for a 256-port switch. For scheduler application-specific integrated circuit (ASIC) synthesis, this reduces to 2.0~ns; a record result enabling scalable packet switching. Furthermore, the control plane was demonstrated experimentally. Moreover, a cycle-accurate network emulator was developed to evaluate switch performance. Results showed a switch saturation throughput at a traffic load 60\% of capacity, with sub-microsecond packet latency, for a 256-port Clos switch, outperforming state-of-the-art optical packet switches
Parallel Desynchronized Block Matching: A Feasible Scheduling Algorithm for the Input-Buffered Wavelength-Routed Switch
The input-buffered wavelength-routed (IBWR) switch is a promising switching architecture for slotted optical packet switching (OPS) networks. The benefits of the IBWR fabric are a better scalability and lower hardware cost, when compared to output buffered OPS proposals. A previous work characterized the scheduling problem of this architecture as a type of matching problem in bipartite graphs. This characterization establishes an interesting relation between the IBWR scheduling and the scheduling of electronic virtual output queuing switches. In this paper, this relation is further explored, for the design of feasible IBWR scheduling algorithms, in terms of hardware implementation and execution time. As a result, the parallel desynchronized block matching (PDBM) algorithm is proposed. The evaluation results presented reveal that IBWR switch performance using the PDBM algorithm is close to the performance bound given by OPS output buffered architectures. The performance gap is especially small for dense wavelength division multiplexing (DWDM) architectures.This research has been funded by the Spanish MCyT grant TEC2004-05622-C04-02/TCM (ARPaq).
Authors would like to thank also the COST 291 action and the e-Photon/ONe+ European Network of
Excellence
Getting routers out of the core: Building an optical wide area network with "multipaths"
We propose an all-optical networking solution for a wide area network (WAN)
based on the notion of multipoint-to-multipoint lightpaths that, for short, we
call "multipaths". A multipath concentrates the traffic of a group of source
nodes on a wavelength channel using an adapted MAC protocol and multicasts this
traffic to a group of destination nodes that extract their own data from the
confluent stream. The proposed network can be built using existing components
and appears less complex and more efficient in terms of energy consumption than
alternatives like OPS and OBS. The paper presents the multipath architecture
and compares its energy consumption to that of a classical router-based ISP
network. A flow-aware dynamic bandwidth allocation algorithm is proposed and
shown to have excellent performance in terms of throughput and delay
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