No description available.

No description available.

No description available.

Intrusive monitoring systems monitor the performance of data communication networks by transmitting and receiving test packets on the network being monitored. Even relatively small periods of monitoring can generate significantly large amounts of data. Primitive network performance data are details of test packets that are transmitted and received over the network under test. Network performance information is then derived by significantly processing the primitive performance data. This information may need to be correlated with information regarding the configuration and status of various network elements and the test stations. This thesis suggests that efficient processing of the collected data may be achieved by reusing and recycling the derived information in the data warehouses and information systems. This can be accomplished by pre-processing the primitive performance data to generate Intermediate Information. In addition to being able to efficiently fulfil multiple information requirements, different Intermediate Information elements at finer levels of granularity may be recycled to generate Intermediate Information elements at coarser levels of granularity. The application of these concepts in processing packet delay information from the primitive performance data has been studied. Different Intermediate Information structures possess different characteristics. Information systems can exploit these characteristics to efficiently re-cycle elements of these structures to derive the required information elements. Information systems can also dynamically select appropriate Intermediate Information structures on the basis of queries posted to the information system as well as the number of suitable Intermediate Information elements available to efficiently answer these queries. Packet loss and duplication summaries derived for different analysis windows also provide information regarding the network performance characteristics. Due to their additive nature, suitable finer granularity packet loss and duplication summaries can be added to provide coarser granularity packet loss and duplication summaries.

No description available.

M.Ing. / Data communications have increased tremendously over the last few years. Therefore, it is important to use the potential large bandwidth of the existing optical fibre network to satisfy the demand. Wavelength-division multiplexing (WDM) enables one to have several channels on a single fibre while the system remains transparent for the bit rate and format of the signals on the individual channels. Erbium doped fibre lasers have narrow linewidths and the wavelength is tunable over the optical amplifier wavelength range. They are therefore very attractive sources to test WDM systems. The exciting possibility of simultaneous laser action at predetermined wavelengths X,, X2, ... , X, makes the fibre laser a very important source for WDM systems. In this work we concentrated on two ring laser configurations. The first one uses a tunable Fabry-Perot filter, whereas the second one has a polarization filter for tunability and wavelength selection. The Fabry-Perot filter had a finesse of 167, a bandwidth of 30.0 GHz and a free spectral range of 5010 GHz. This laser configuration was tunable from 1546.52 nm to 1584.04 nm (37.52 nm) and the linewidth was less than 0.037 nm. The polarization filter comprised a 31X-polarization controller, two XJ4-polarization controllers, a X/2-polarization controller for wavelength tunability and a polarizer. This ring laser was tunable from 1559.59 nm to 1568.69 nm (9.1 nm) and had a linewidth of less than 0.037 nm. We obtained a slope efficiency of 17.6 % for the erbium doped fibre laser. For the first time computer software was developed that makes use of the Poincare sphere and Jones matrices to present the state of polarization and the operation of a polarization filter visually. The power spectra of both ring laser configurations were determined as a function of the output coupling using signal flow diagrams and the power equations for the ring laser. According to our knowledge, the influence of the output coupler on the finesse and the linewidth of the fibre ring laser has been studied for the first time.

<p>Different types of models often require different tools and environments to be modeled and simulated. These tools and environments are specialized to handle specific purposes. The models created for these special purposes can then be included in the modeling and simulation of large complex systems. This scenario increases the motivation to use a co-simulation technique. Co-simulation allows for coupling of different simulators into one coherent simulation. Different parts of a system are often modeled by different departments within an enterprise or by subcontractors. Since the models often are describing enterprises’ primary know-how they become important business assets. This raises the need for a secure modeling and simulation approach. This thesis discusses different approaches regarding how to securely simulate and distribute models. We focus on a distributed co-simulation approach over wide area networks (WANs), using transmission line modeling (TLM). The approach is tested in an experimental environment at Linköping University, Sweden, and by real condition co-simulations between Sweden and Australia. A series of experiments are conducted using a simulated WAN environment and the results are put in relation to the real encrypted simulations between Sweden and Australia. We measure the performance during the simulations and evaluate the results. We observe that by distributing the co-simulation we suffer from performance losses. These losses and what parameters cause them is our primary emphasis in the evaluation. We also see that there are two types of parameters that affect the total simulation time in the distributed environment. First there are parameters that belong to the models, and then there are parameters that belong to the WAN environment. We conclude that several of the parameters have effect on the total simulation time. Especially the network delay (latency) has a significant impact.</p>

MSc, PU vir CHO, 1993

MSc, PU vir CHO, 1993

Different types of models often require different tools and environments to be modeled and simulated. These tools and environments are specialized to handle specific purposes. The models created for these special purposes can then be included in the modeling and simulation of large complex systems. This scenario increases the motivation to use a co-simulation technique. Co-simulation allows for coupling of different simulators into one coherent simulation. Different parts of a system are often modeled by different departments within an enterprise or by subcontractors. Since the models often are describing enterprises’ primary know-how they become important business assets. This raises the need for a secure modeling and simulation approach. This thesis discusses different approaches regarding how to securely simulate and distribute models. We focus on a distributed co-simulation approach over wide area networks (WANs), using transmission line modeling (TLM). The approach is tested in an experimental environment at Linköping University, Sweden, and by real condition co-simulations between Sweden and Australia. A series of experiments are conducted using a simulated WAN environment and the results are put in relation to the real encrypted simulations between Sweden and Australia. We measure the performance during the simulations and evaluate the results. We observe that by distributing the co-simulation we suffer from performance losses. These losses and what parameters cause them is our primary emphasis in the evaluation. We also see that there are two types of parameters that affect the total simulation time in the distributed environment. First there are parameters that belong to the models, and then there are parameters that belong to the WAN environment. We conclude that several of the parameters have effect on the total simulation time. Especially the network delay (latency) has a significant impact.