372 research outputs found
Performance analysis of Gb/s WDM FDDI network
In this paper, we propose a time-token multi-Gb/s Wavelength Division Multiplexing Fibre Distributed Data Interface (WDM/FDDI) architecture and examine its throughput efficiency and delay under heavy load for different network configuration using discrete event simulator
An Overview of the Isochronets Architecture for High Speed Networks
This paper overviews a novel switching architecture for high-speed networks: Isochronets. Isochronets time-divide network bandwidth among routing trees. Traffic moves down a routing tree to the root during its time band. Network functions such as routing and flow control are entirely governed by band timers and require no processing of frame headers bits. Frame motions need not be delayed for switch processing, allowing Isochronets to scale over a large spectrum of transmission speeds and support all-optical implementations. The network functions as a media-access layer that can support multiple framing protocols simultaneously, handled by higher layers at the periphery. Internetworking is reduced to a simple media-layer bridging. Isochronets provide flexible quality of service control and multicasting through allocation of bands to routing trees. They can be tuned to span a spectrum of performance behaviors outperforming both circuit or packet switching
Hybrid Wavelength Routed and Optical Packet Switched Ring Networks for the Metropolitan Area Network
Performance Studies of a Double-Layered All-Optical Network Architecture
Transmission in complete lightform is now realised with advancements in technology. These include new developments in fabricating the fiber carrier
medium, low loss fiber coupling devices, optical switching components for routing
lightwave trans mission; laser light sources and sensitive photonic detectors. The
in creasing speeds of new generation electronic microprocessors, is capable of
resolving the differences in processing and transmission speeds. Access to the
medium is regulate d by the medium access control protocol, that permits multiple
users to share limited transmission resources of the network. The double-layere dhierarchical all-optical network architecture is proposed, that consists of an upper
layer to inter connect sub-networks of the lower layer. The data packets are
differentiate d for the two layers . The architecture implements wavelength -space
trans mission of wavelength division multiplexed channels. The architecture affords spatial reuse of channels in the lower layer. A non-contentious token-passing
medium access protocol is utilised. The token-passing variant that uses one token to
provide access to multiple channels is introduced.
The performance of the arrayed transmitter of the access node is gauged to
determine the suitability of the architecture with the access protocol in supporting
multiple accesses. The transmitter can queue a number of data packets awaiting
transmission depending on the size of the buffer. Performance indication can be
obtained from probabilistic modelling of the changing event states of the
transmitter. Performance causal parameters which include the number of nodes,
channel allocation and buffer size are defined. The results from the probabilistic
models are then analysed and verified with simulation. The architecture provides an
inherent feature termed as the bypass that is capitalised to improve performance of
the lower layer. Performance indication shows that the architecture is capable of
supporting the two types of data packets effectively, and the access protocol is
suitable for its purpose. Performance indication of average packet delay improves
when the when the bypass feature is implemented. The probabilistic models are
found to provide a logical and systematic approach to study and gauge performance
of the token-passing access protocol. In conclusion, the double-layered hierarchical
AON architecture and the medium access protocol, together serve as a reference for
the study of similar scaleable network architectures and their performance
Design Related Investigations for Media Access Control Protocol Service Schemes in Wavelength Division Multiplexed All Optical Networks
All-optical networks (AON) are emerging through the technological
advancement of various optical components, and promise to provide almost unlimited
bandwidth. To realise true network utilisation, software solutions are required. An active
area of research is media access control (MAC) protocol. This protocol should address
the multiple channels by wavelength division mutiplexing (WDM) and bandwidth
management. Token-passing (TP) is one such protocol, and is adopted due to its
simplicity and collisionless nature. Previously, this protocol has been analysed for a
single traffic type. However, such a study may not substantiate the protocol's acceptance
in the AON design. As multiple traffic types hog the network through the introduction
multimedia services and Internet, the MAC protocol should support this traffic. Four
different priority schemes are proposed for TP protocol extension, and classified as static and dynamic schemes. Priority assignments are a priori in static scheme, whereas in the
other scheme, priority reassignments are carried out dynamically. Three different
versions of dynamic schemes are proposed. The schemes are investigated for
performance through analytical modelling and simulations. The semi-Markov process
(SMP) modelling approach is extended for the analyses of these cases. In this technique,
the behaviour of a typical access node needs to be considered. The analytical results are
compared with the simulation results. The deviations of the results are within the
acceptable limits, indicating the applicability ofthe model in all-optical environment.
It is seen that the static scheme offers higher priority traffic better delay and
packet loss performance. Thus, this scheme can be used beneficially in hard real-time
systems, where knowledge of priority is a priori. The dynamic priority scheme-l is more
suitable for the environments where the lower priority traffic is near real-time traffic and
loss sensitive too. For such a scheme, a larger buffer with smaller threshold limits
resulted in improved performance. The dynamic scheme-2 and 3 can be employed to
offer equal treatment for the different traffic types, and more beneficial in future AONs.
These schemes are also compared in their performance to offer constant QoS level. New
parameters to facilitate the comparison are proposed. It is observed that the dynamic
scheme-l outperforms the other schemes, and these QoS parameters can be used for
such QoS analysis. It is concluded that the research can benefit the design of the
protocol and its service schemes needed in AON system and its applications
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