625 research outputs found
QoS multicast tree construction in IP/DWDM optical internet by bio-inspired algorithms
Copyright @ Elsevier Ltd. All rights reserved.In this paper, two bio-inspired Quality of Service (QoS) multicast algorithms are proposed in IP over dense wavelength division multiplexing (DWDM) optical Internet. Given a QoS multicast request and the delay interval required by the application, both algorithms are able to find a flexible QoS-based cost suboptimal routing tree. They first construct the multicast trees based on ant colony optimization and artificial immune algorithm, respectively. Then a dedicated wavelength assignment algorithm is proposed to assign wavelengths to the trees aiming to minimize the delay of the wavelength conversion. In both algorithms, multicast routing and wavelength assignment are integrated into a single process. Therefore, they can find the multicast trees on which the least wavelength conversion delay is achieved. Load balance is also considered in both algorithms. Simulation results show that these two bio-inspired algorithms can construct high performance QoS routing trees for multicast applications in IP/DWDM optical Internet.This work was supported in part ny the Program for New Century Excellent Talents in University, the Engineering and Physical Sciences Research Council (EPSRC) of UK under Grant EP/E060722/1, the National Natural Science Foundation of China under Grant no. 60673159 and 70671020, the National High-Tech Reasearch and Development Plan of China under Grant no. 2007AA041201, and the Specialized Research Fund for the Doctoral Program of Higher Education under Grant no. 20070145017
A Novel Network Coded Parallel Transmission Framework for High-Speed Ethernet
Parallel transmission, as defined in high-speed Ethernet standards, enables
to use less expensive optoelectronics and offers backwards compatibility with
legacy Optical Transport Network (OTN) infrastructure. However, optimal
parallel transmission does not scale to large networks, as it requires
computationally expensive multipath routing algorithms to minimize differential
delay, and thus the required buffer size, optimize traffic splitting ratio, and
ensure frame synchronization. In this paper, we propose a novel framework for
high-speed Ethernet, which we refer to as network coded parallel transmission,
capable of effective buffer management and frame synchronization without the
need for complex multipath algorithms in the OTN layer. We show that using
network coding can reduce the delay caused by packet reordering at the
receiver, thus requiring a smaller overall buffer size, while improving the
network throughput. We design the framework in full compliance with high-speed
Ethernet standards specified in IEEE802.3ba and present solutions for network
encoding, data structure of coded parallel transmission, buffer management and
decoding at the receiver side. The proposed network coded parallel transmission
framework is simple to implement and represents a potential major breakthrough
in the system design of future high-speed Ethernet.Comment: 6 pages, 8 figures, Submitted to Globecom201
Design and provisioning of WDM networks for traffic grooming
Wavelength Division Multiplexing (WDM) is the most viable technique for utilizing the enormous amounts of bandwidth inherently available in optical fibers. However, the bandwidth offered by a single wavelength in WDM networks is on the order of tens of Gigabits per second, while most of the applications\u27 bandwidth requirements are still subwavelength. Therefore, cost-effective design and provisioning of WDM networks require that traffic from different sessions share bandwidth of a single wavelength by employing electronic multiplexing at higher layers. This is known as traffic grooming. Optical networks supporting traffic grooming are usually designed in a way such that the cost of the higher layer equipment used to support a given traffic matrix is reduced. In this thesis, we propose a number of optimal and heuristic solutions for the design and provisioning of optical networks for traffic grooming with an objective of network cost reduction. In doing so, we address several practical issues. Specifically, we address the design and provisioning of WDM networks on unidirectional and bidirectional rings for arbitrary unicast traffic grooming, and on mesh topologies for arbitrary multipoint traffic grooming. In multipoint traffic grooming, we address both multicast and many-to-one traffic grooming problems. We provide a unified frame work for optimal and approximate network dimensioning and channel provisioning for the generic multicast traffic grooming problem, as well as some variants of the problem. For many-to-one traffic grooming we propose optimal as well as heuristic solutions. Optimal formulations which are inherently non-linear are mapped to an optimal linear formulation. In the heuristic solutions, we employ different problem specific search strategies to explore the solution space. We provide a number of experimental results to show the efficacy of our proposed techniques for the traffic grooming problem in WDM networks
Avoidance of multicast incapable branching nodes for multicast routing in WDM networks
In this articlewestudy themulticast routing problem in all-opticalWDMnetworks
under the spare light splitting constraint. To implement a multicast session,
several light-trees may have to be used due to the limited fanouts of network
nodes. Although many multicast routing algorithms have been proposed in order
to reduce the total number of wavelength channels used (total cost) for a
multicast session, the maximum number of wavelengths required in one fiber link
(link stress) and the end-to-end delay are two parameters which are not always
taken into consideration. It is known that the shortest path tree (SPT) results
in the optimal end-to-end delay, but it can not be employed directly for
multicast routing in sparse light splitting WDM networks. Hence, we propose a
novel wavelength routing algorithm which tries to avoid the multicast incapable
branching nodes (MIBs, branching nodes without splitting capability) in the
shortest-path-based multicast tree to diminish the link stress. Good parts of
the shortest-path-tree are retained by the algorithm to reduce the end-to-end
delay. The algorithm consists of tree steps: (1) aDijkstraPro algorithmwith
priority assignment and node adoption is introduced to produce a SPT with up to
38% fewer MIB nodes in the NSF topology and 46% fewerMIB nodes in the USA
Longhaul topology, (2) critical articulation and deepest branch heuristics are
used to process the MIB nodes, (3) a distance-based light-tree reconnection
algorithm is proposed to create the multicast light-trees. Extensive
simulations demonstrate the algorithm's efficiency in terms of link stress and
end-to-end delay
1 x M packet-switched router based on the PPM header address for all-optical WDM networks
This paper presents an all-optical 1xM router architecture for simultaneous multiple-wavelength packet routing, without the need for wavelength conversion. The packet header address is based on the pulse position modulation (PPM) format, which allows the use of only a single-bitwise optical AND gate for fast packet header address correlation. The proposed scheme offers both multicast and broadcast capabilities. Weâve demonstrated a high speed packet routing at 160 Gb/s in simulation, with a low channel crosstalk (CXT) of ~ -27 dB with a channel spacing of > 0.4 THz and a demultiplexer bandwidth of 500 GHz. The output transfer function of the PPM header processing (PPM-HP) module is also investigated in this paper
Performance improvement of an optical network providing services based on multicast
Operators of networks covering large areas are confronted with demands from
some of their customers who are virtual service providers. These providers may
call for the connectivity service which fulfils the specificity of their
services, for instance a multicast transition with allocated bandwidth. On the
other hand, network operators want to make profit by trading the connectivity
service of requested quality to their customers and to limit their
infrastructure investments (or do not invest anything at all).
We focus on circuit switching optical networks and work on repetitive
multicast demands whose source and destinations are {\em \`a priori} known by
an operator. He may therefore have corresponding trees "ready to be allocated"
and adapt his network infrastructure according to these recurrent
transmissions. This adjustment consists in setting available branching routers
in the selected nodes of a predefined tree. The branching nodes are
opto-electronic nodes which are able to duplicate data and retransmit it in
several directions. These nodes are, however, more expensive and more energy
consuming than transparent ones.
In this paper we are interested in the choice of nodes of a multicast tree
where the limited number of branching routers should be located in order to
minimize the amount of required bandwidth. After formally stating the problem
we solve it by proposing a polynomial algorithm whose optimality we prove. We
perform exhaustive computations to show an operator gain obtained by using our
algorithm. These computations are made for different methods of the multicast
tree construction. We conclude by giving dimensioning guidelines and outline
our further work.Comment: 16 pages, 13 figures, extended version from Conference ISCIS 201
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