In times of network convergence and increasingly challenging customer demands, automated tools can help operating next generation networks more efficiently. Since operators have different ideas and requirements about the strategies they use for network operation and maintenance, automated solutions need to be very flexible. This paper presents a concept that allows for an easy and flexible configuration of the operational strategy carried out by a traffic and performance management node

This work focuses on capacity overprovisioning (CO) as an alternative to admission control (AC) to implement quality of service (QoS) in packet-switched communication networks. CO prevents potential overload while AC protects the QoS of the traffic during overload situations. Overload may be caused, e. g., by uctuations of the traffic rate on a link due to its normal stochastic behavior (a), by traffic shifts within the network due to popular contents (b), or by redirected traffic due to network failures (c). Capacity dimensioning methods for CO need to take into account all potential sources of overload while AC can block excess traffic caused by (a) and (b) if the capacity does not suffice. The contributions of this paper are (1) the presentation of a capacity dimensioning method for networks with resilience requirements and changing traffic matrices, (2) the investigation of the impact of the mentioned sources of overload (a-c) on the required capacity for CO in networks with and without resilience requirements, and (3) a comparison of this equired capacity with the one for AC. Our results show that in the presence of strong traffic shifts CO requires more capacity than AC. However, if resilience against network failures is required, both CO and AC need additional backup capacity for the redirected traffic. In this case, CO can use the backup capacity to absorb other types of overload. As a consequence, CO and AC have similar bandwidth requirements. These findings are robust against the network size.

In this paper we describe the new concept of network admission control (NAC) and delimit it against link admission control (LAC). Four basically different budget based NAC methods are presented.

A variety of Internet traffic characterization and source models already exist. Since the origin of the analyzed data differs, a comparison of the reported traffic characteristics is difficult. In this paper we analyze an IP packet trace and relate the trace data to the user access speed recorded at the same time. The obtained characteristics are contrasted with a second data set measured within an ADSL field trial. This second data set represents a limit in Internet usage, since, the high speed access was provided free of charge. This comparison leads to some interesting insights showing whether and how the access speed influences the Internet user behavior and thus the generated source traffic. The derived Internet traffic characterization is a first step to a generalized parametric Internet traffic model.

This paper compares activity polling mechanisms occurring in a class of media access control (MAC) protocols for passive tree or star networks. An analytical model is developed which explains the function of polling mechanisms in MAC protocols for the single source case, i.e., with one on-off source present in the whole system. Results from this model are compared to simulation results for the single source case and for multiple source cases. It is shown that these analytical results can furthermore explain the main effects seen under normal load, and the analysis is extended to a contention based mechanism, leading to a fair parametric comparison between activity polling and activity contention under comparable conditions. The final result quantifies the range of parameters (round-trip time and fraction of active stations) where a contention mechanism can give better delay quantile performance than a polling mechanism.