**6. References**


nodes with dedicated wavelength converters. Particularly, with TE-DBS around 16 shared converters per node are enough to match the loss performance obtained with 64 dedicated converters, whereas with BORA this number more than doubles, since around 36 shared converters are required. The larger savings in the number of wavelength converters enabled by TE-DBS also mean that the expansion of the switch matrix to accommodate the shared

Optical burst switching is seen as a candidate technology for next-generation transport networks. This chapter has described and analyzed the performance benefits of a strategy to enforce traffic engineering in the wavelength domain in OBS networks. The TE-DBS strategy is based on using the HMPI algorithm to optimize offline the order by which wavelength channels are searched for each routing path and employing at the ingress nodes a selective delaying of data bursts as a way to maximize the amount of burst traffic sent via the wavelength channels ranked with highest priority. Both the HMPI offline algorithm and the

A network simulation study has highlighted the performance improvements attained by using TE-DBS in an OBS network with dedicated full-range wavelength converters and with shared full-range wavelength converters. It was shown that the utilization of the TE-DBS strategy enables to reduce the average burst blocking probability for a given average offered traffic load, or augment the average offered traffic load for an objective burst blocking probability, when compared to utilizing a known contention minimization strategy. The simulation results shown that increasing the maximum delay a burst can experience at the ingress node and augmenting the number of wavelength channels per link can improve the effectiveness of the TE-DBS strategy and also provided evidence of the burst serialization and traffic isolation in different wavelengths inherent to this strategy. Finally, the analysis confirms that the utilization of TE-DBS in OBS networks with shared full-range wavelength converters can provide noticeable savings in the number of expensive all-optical wavelength converters and a smaller increase in the size

Barakat, N. & Darcie, T. (2007). The Control-Plane Stability Constraint in Optical Burst

Chai, T.; Cheng, T. ; Shen, G.; Bose, S. & Lu, C. (2002). Design and Performance of Optical

Chang, G.; Yu, J. ; Yeo, Y.; Chowdhury, A. & Jia, Z. (2006). Enabling Technologies for Next-

Chen, Y.; Qiao, C. & Yu, X. (2004). Optical Burst Switching: A New Area in Optical

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Switching Networks. *IEEE Communications Letters*, Vol. 11, No. 3, (March 2007), pp.

Cross-Connect Architectures with Converter Sharing. *Optical Networks Magazine*,

Generation Packet-Switching Networks. *Proceedings of the IEEE*, Vol. 94, No. 5, (May

Networking Research. *IEEE Network*, Vol. 18, No. 3, (May/June 2004), pp. 16-23,

converters is smaller, leading to an even more cost-effective network solution.

online selective delaying of bursts were revisited and exemplified.

of the switch matrix of the core nodes.

267-269, ISSN 1089-7798

ISSN 0890-8044

2006), pp. 892-910, ISSN 0018-9219

**6. References** 

**5. Conclusions** 


**13** 

*Spain* 

**Modelling a Network Traffic Probe** 

Luis Zabala, Armando Ferro,

Alberto Pineda and Alejandro Muñoz *University of the Basque Country (UPV/EHU)* 

**Over a Multiprocessor Architecture** 

The need to monitor and analyse data traffic grows with increasing network usage by businesses and domestic users. Disciplines such as security, quality of service analysis, network management, billing and even routing require traffic monitoring and analysis systems with high performance. Thus, the increasing bandwidth in data networks and the amount and variety of network traffic have increased the functional requirements for applications that capture, process or store monitored traffic. Besides, the availability of capture hardware (monitoring cards, taps, etc.) and mass storage solutions at a reasonable cost makes the situation better in the field of network traffic monitoring. For these reasons, several research groups are studying how to monitor heterogeneous network environments, such as wired broadband backbone networks, next generation cellular networks, high-speed access networks or WLAN in campus-like environments. In keeping with this line, our research group NQaS (Networking, Quality and Security) aims to contribute in this challenge and presents theoretical and experimental research to study the behaviour of a probe (Ksensor) that can perform traffic capturing and analysis tasks in Gigabit Ethernet networks. Not only do we intend to progress in the design of traffic analysis systems, but we

also want to obtain mathematical models to study the performance of these devices.

able to process all the information carried by actual networks.

The widespread of 1/10 Gigabit Ethernet networks, emphasizes the problems related to system losses which invalidate the results for certain analyses. New Gigabit networks, even at 40 and 100 Gbps, are already being implemented and the problem becomes accentuated. On top of that, commodity systems are not optimized for monitoring [Wang&Liu, 2004] and, as a result, processing resources are often wasted on inefficient tasks. Because of this, new research works have arisen focusing on the development of analysis systems that are

Taking all this into account, we would like to develop analytical models that represent traffic monitoring systems in order to provide solutions to the problems mentioned before. Modelling helps to predict the system's performance when it is subjected to a variety of network traffic load conditions. Designers and administrators can identify bottlenecks, deficiencies and key system parameters that impact its performance, and thereby the system can be properly tuned to give the optimal performance. By means of modelling technique, it

**1. Introduction** 

*Communications Magazine*, Vol. 43, No. 11, (November 2005), pp. s48-s55, ISSN 0163- 6804

