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IP networks have established as a global telecommunication platform with increasing user population and an extending spectrum of services. The traffic is also steadily increasing, recently driven by peer to peer networking in addition to client server based applications. Network planers and operators have to ensure the scalability of IP platforms in a permanent upgrade process for transmission capacities. At present, Deutsche Telekom and other telecommunication network providers are introducing traffic engineering methods to achieve an optimum resource utilization.In a first step, traffic engineering can be applied to a predefined network topology, but a comprehensive approach has to be coordinated with a process for upgrading the link capacities and has to prepare for relevant failure scenarios. We have evaluated the efficiency of traffic engineering together with simple link upgrade strategies in order to get a maximum throughput. Therefore a predefined traffic matrix T is taken into account. The optimization goal is to scale the traffic matrix by a maximum factor λ max such that the traffic demand λ max T can still be carried on the available network resources. The influence of the network topology on the evaluation results is shown in examples with regard to single link failures.

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In this paper we consider the problem of determining traffic matrices for end-to-end demands in an IP/MPLS network that supports multiple quality of service (QoS) classes. More precisely, we want to determine the set of traffic matrices T i for each QoS class i separately. T i contains average bandwidth levels for QoS class i for every pair of routers within the network. We propose a new method for obtaining QoS class specific traffic matrices that combines estimation and measurement methods: We take advantage of the fact that the total traffic matrix can be measured precisely in MPLS networks using either the LDP or RSVP-TE protocol. These measurements can then be used in a mathematical model to improve estimation methodsknown as network tomography -that estimate QoS class specific traffic matrices from QoS class specific link utilizations. In addition to the mathematical model, we present results of the proposed method from its application in Deutsche Telekom's global IP/MPLS backbone network and we show that the estimation accuracy (mean relative error) is improved by a factor of 2.5 compared to results from network tomogravity. We investigate the structure of the estimated traffic matrices for the different QoS classes and motivate in this paper why QoS class specific traffic matrices will be essential for efficient network planning and network engineering in the future.

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