969 research outputs found
Flow control and service differentiation in optical burst switching networks
Cataloged from PDF version of article.Optical Burst Switching (OBS) is being considered as a candidate architecture
for the next generation optical Internet. The central idea behind OBS is the assembly
of client packets into longer bursts at the edge of an OBS domain and the
promise of optical technologies to enable switch reconfiguration at the burst level
therefore providing a near-term optical networking solution with finer switching
granularity in the optical domain. In conventional OBS, bursts are injected to
the network immediately after their assembly irrespective of the loading on the
links, which in turn leads to uncontrolled burst losses and deteriorating performance
for end users. Another key concern related to OBS is the difficulty of
supporting QoS (Quality of Service) in the optical domain whereas support of
differentiated services via per-class queueing is very common in current electronically
switched networks. In this thesis, we propose a new control plane protocol,
called Differentiated ABR (D-ABR), for flow control (i.e., burst shaping) and
service differentiation in optical burst switching networks. Using D-ABR, we
show with the aid of simulations that the optical network can be designed to
work at any desired burst blocking probability by the flow control service of the proposed architecture. The proposed architecture requires certain modifications
to the existing control plane mechanisms as well as incorporation of advanced
scheduling mechanisms at the ingress nodes; however we do not make any specific
assumptions on the data plane of the optical nodes. With this protocol, it is
possible to almost perfectly isolate high priority and low priority traffic throughout
the optical network as in the strict priority-based service differentiation in
electronically switched networks. Moreover, the proposed architecture moves the
congestion away from the OBS domain to the edges of the network where it is
possible to employ advanced queueing and buffer management mechanisms. We
also conjecture that such a controlled OBS architecture may reduce the number
of costly Wavelength Converters (WC) and Fiber Delay Lines (FDL) that are
used for contention resolution inside an OBS domain.Boyraz, HakanM.S
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
Service-Oriented Multigranular Optical Network Architecture for Clouds
This paper presents a novel service-oriented network architecture to bridge the informational gap between user applications and optical networks providing technology-agnostic multigranular optical network services for clouds. A mediation layer (service plane) between user applications and network control is proposed to facilitate a mapping process between user application requests and the network services. At the network level, a multigranular optical network (MGON) is proposed and implemented to support dynamic wavelength and subwavelength granularities with different transport formats [optical burst switched (OBS), optical burst transport (OBT)], reservation protocols (one-way, two-way), and different quality-of-service (QoS) levels per service type. The service-oriented multigranular optical network has been designed, implemented, and demonstrated on an experimental testbed. The testbed consists of service and network resource provisioning, service abstraction, and network resource virtualization. The service-to-network interoperation is provided by means of a gateway that maps service requests to technology-specific parameters and a common signaling channel for both service and network resource provisioning
Performance Evaluation of the Labelled OBS Architecture
A comparison of three different Optical Burst Switching (OBS) architectures
is made, in terms of performance criteria, control and hardware complexity,
fairness, resource utilization, and burst loss probability. Regarding burst
losses, we distinguish the losses due to burst contentions from those due to
contentions of Burst Control Packets (BCP). The simulation results show that as
a counterpart of an its additional hardware complexity, the labelled OBS
(L-OBS) is an efficient OBS architecture compared to a Conventional OBS (C-OBS)
as well as in comparison with Offset Time-Emulated OBS (E-OBS)
A Novel QoS provisioning Scheme for OBS networks
This paper presents Classified Cloning, a novel QoS provisioning mechanism for OBS networks carrying real-time
applications (such as video on demand, Voice over IP, online
gaming and Grid computing). It provides such applications with a minimum loss rate while minimizing end-to-end delay and jitter. ns-2 has been used as the simulation tool, with new OBS modules having been developed for performance evaluation purposes. Ingress node performance has been investigated, as well as the overall performance of the suggested scheme. The results obtained showed that new scheme has superior performance to classical cloning. In particular, QoS provisioning offers a guaranteed burst loss rate, delay and expected value of jitter, unlike existing proposals for QoS implementation in OBS which use the burst offset time to provide such differentiation. Indeed, classical schemes increase both end-to-end delay and
jitter. It is shown that the burst loss rate is reduced by 50% reduced over classical cloning
Performance and cost analysis of all-optical switching: OBS and OCS
This paper presents a study of performance and cost analysis of optical circuit switching (OCS) and optical burstswitching (OBS) by proposing the clear images of their node architectures and cost formulations. Then, we apply servicelevel agreement (SLA) of the high quality of service application in the terms of network blocking probability and averagenetwork delay to demonstrate OCS and OBS performances, their investment costs, and network dimensioning methodology.Applying SLA to our studies can illustrate the impact of contention resolution and blocking resolution schemes to theperformances and costs of OBS and OCS, accordingly. The simulations illustrate that OBS applying WC gives the bestperformance among all architectures deploying the same offered bandwidth. The investigations also show that WC is a majortechnique contributing high performance gain to both OCS and OBS. Especially for OBS, WC is an important scheme allowingOBS high data grooming property as its performance gain contributing to OBS is much higher than those of OCS. For thecost analysis, OCS is the most economic among all architectures. BA provides the most cost effectiveness among all OBScontention resolution schemes. Lastly, FDL is the least cost effective scheme as it gives little performance enhancement butadds more cost to the network
Burst switched optical networks supporting legacy and future service types
Focusing on the principles and the paradigm of OBS an overview addressing expectable performance and application issues is presented. Proposals on OBS were published over a decade and the presented techniques spread into many directions. The paper comprises discussions of several challenges that OBS meets, in order to compile the big picture. The OBS principle is presented unrestricted to individual proposals and trends. Merits are openly discussed, considering basic teletraffic theory and common traffic characterisation. A more generic OBS paradigm than usual is impartially discussed and found capable to overcome shortcomings of recent proposals. In conclusion, an OBS that offers different connection types may support most client demands within a sole optical network layer
Resource reservation protocols for optical burst switched networks
Nesta disserta c~ao e feito um estudo em redes com comuta c~ao optica de agregados
de pacotes (redes OBS). Assim, este estudo apresenta e descreve os conceitos
mais importantes relacionados com as redes OBS.
Inicialmente e analisado o estado da arte, efectuando uma descri c~ao detalhada
da arquitectura de uma rede OBS.
Seguidamente analisam-se os protocolos de reserva unidireccional de recursos
(JIT, JIT+, JET, Jumpstart, Horizon and E-JIT). Para isso s~ao utilizadas redes
com topologias regulares (em anel e em malha) com um n umero vari avel de n os,
e tamb em irregulares (NSFNET e ARPANET). E tamb em apresentado um novo
protocolo de reserva unidireccional de recursos chamado E-JIT+.
Este novo protocolo baseia-se no protocolo j a existente JIT+ e tenta optimizar
o seu desempenho. Para melhor descrever o modo de opera c~ao deste
protocolo proposto e apresentada a especi ca c~ao formal do mesmo. Depois da
apresenta c~ao deste protocolo analisa-se o seu desempenho. Para isso s~ao utilizadas
as topologias de rede referidas anteriormente e tamb em um simulador de
redes OBS adaptado de forma a suportar o novo protocolo.
O simulador utilizado, de nome OBSSimulator, devolve os valores de probabilidade
de perda dos agregados de pacotes em cada salto (hop) na rede. Deste
modo, foram considerados v arios factores que podem in
uenciar o desempenho
dos protocolos de reserva unidireccional de recursos, tais como o n umero de n os
da topologia de rede utilizada, a quantidade de tr afego na rede, o ganho do
grau nodal, o tempo de processamento das mensagens de setup e o tempo de
con gura c~ao dos comutadores opticos. No m deste trabalho concluiu-se que
o protocolo proposto, E-JIT+, melhora o desempenho em rela c~ao aos outros
protocolos de reserva unidireccional de recursos estudados, nos casos estudados
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