Abstract. This paper proposes an integrated network management framework for interdomain outbound traffic engineering. The framework consists of three functional blocks (monitoring, optimization and implementation) to make the outbound traffic engineering adaptive to network condition changes such as inter-domain traffic demand variation, routing changes and link failure. The objective is to keep inter-domain link utilization load balanced under any of these changes while reducing service disruptions and reconfiguration overheads. Simulation results demonstrate that using the proposed framework can successfully achieve better load balancing with less service disruptions and re-configuration overheads compared to the alternative approaches. IntroductionOutbound Traffic Engineering (TE) [1,2,3,4] has become increasingly important and been well studied, and is a set of techniques for controlling traffic exiting a domain by assigning the traffic to the best egress points (i.e. routers or links).. The general problem formulation of outbound TE is: given the network topology, BGP routing information and inter-domain Traffic Matrix (TM), determine the best Egress Point (EP) for each traffic demand so as to optimize the overall network performance [2]. Since inter-domain links are the most common bottlenecks in the Internet [2], optimizing their resource utilization becomes a key objective of outbound TE.In practice, network conditions change dynamically, which can make the current outbound TE solutions obsolete and subsequently cause some inter-domain links to become congested over time. One such dynamic change is inter-domain traffic variation, which is typically caused by changes in user or application behavior, adaptations from the TCP congestion control or even routing changes from other domains [5]. In addition to these traffic variations, transient and non-transient inter-domain peering link failures might occur. According to [7] transient inter-domain link failures are common events and their duration is less than a few minutes. Upon failure on a peering link, there may be a large amount of traffic shifted to other available EPs, potentially leading to congestion on these new serving EPs if they are not carefully chosen. In theory, although it is possible to perform outbound TE based on the other proposals in the literature [2,3,4] whenever any of those changes occur, it may require huge computational overheads and a large number of EP reconfigurations given that previous proposals have not considered the reduction of reconfiguration changes and overheads. This can lead to excessive service disruptions and is not practical. As a consequence, lack of TE solutions that react to those dynamic changes rapidly will leave the network unmanaged. It is thus the focus of this paper to make outbound TE more adaptive to fast-changing IP networks by taking into consideration practical network operation and management constraints such as time-efficiency, reconfiguration overheads and service disruptions.In this paper, we pro...

Abstract. The replica server placement problem determines the optimal location where replicated servers should be placed in content distribution networks, in order to optimize network performance. The estimated traffic demand is fundamental input to this problem and its accuracy is essential for the target performance to be achieved. However, deriving accurate traffic demands is far from trivial and uncertainty makes the target performance hard to predict. We argue that it is often inappropriate to optimize the performance for only a particular set of traffic demands that is assumed accurate. In this paper, we propose a scenario-based robust optimization approach to address the replica server placement problem under traffic demand uncertainty. The objective is to minimize the total distribution cost across a variety of traffic demand scenarios while minimizing the performance deviation from the optimal solution. Empirical results demonstrate that robust optimization for replica server placement can achieve good performance under all the traffic demand scenarios while nonrobust approaches perform significantly worse. This approach allows content distribution providers to provision better and predictable quality of service for their customers by reducing the impact of inaccuracy in traffic demand estimation on the replica server placement optimization.

Abstract

Abstract. Offline inter-domain outbound Traffic Engineering (TE) can be formulated as an optimization problem whose objective is to determine primary egress points for traffic exiting a domain. However, when egress point failures happen, congestion may occur if secondary egress points are not carefully determined. In this paper, we formulate a bi-level outbound TE problem in order to make outbound route selection robust to egress point failures. We propose a tabu search heuristic to solve the problem and compare the performance to three alternative approaches. Simulation results demonstrate that the tabu search heuristic achieves the best performance in terms of our optimization objectives and also keeps traffic disruption to a minimum.

Inter-AS outbound traffic engineering (TE) is a set of techniques for controlling inter-AS traffic exiting an autonomous system (AS) by assigning the traffic to the best egress points (i.e. routers or links) from which the traffic is forwarded to adjacent ASes towards the destinations. In practice, changing network conditions such as inter-AS traffic demand variation, link failures and inter-AS routing changes occur dynamically. These changes can make fixed outbound TE solutions inadequate and may subsequently cause inter-AS links to become congested. In order to overcome this problem, we propose the deployment of a closed loop control traffic engineering system that makes outbound traffic robust to inter-AS link failures and adaptive to changing network conditions. The objective is to keep the inter-AS link utilization balanced under unexpected events while reducing service disruption and reconfiguration overheads. Our evaluation results show that the proposed system can successfully achieve better load balancing with less service disruption and re-configuration overhead in comparison to alternative approaches.

Inter-AS outbound Traffic Engineering (TE) aims to control the flow of traffic exiting an AS so as to optimize inter-AS TE objectives such as load balancing among multiple downstream ASes. The inter-AS traffic matrix is fundamental input for outbound TE and its accuracy is essential for the target performance to be achieved. However, deriving an accurate traffic matrix is far from trivial. This paper proposes a robust approach for outbound TE to manage traffic demand uncertainty through Scenario-based Robust Optimization. The objective of this robust outbound TE is to minimize the worstcase maximum inter-AS link utilization across a set of inter-AS traffic matrices while minimizing the performance deviation from the optimal solutions. Simulation results reveal that the robust outbound TE is capable of achieving reasonably good performance under all the given traffic matrices while nonrobust approaches are not.

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Abstract. Highly available and resilient networks play a decisive role in today's networked world. As network faults are inevitable and networks are becoming constantly intricate, finding effective fault recovery solutions in a timely manner is becoming a challenging task for administrators. Therefore, an automated mechanism to support fault resolution is essential towards efficient fault handling process. In this paper we propose an architecture to support automated fault recovery in terms of traffic engineering, recovery knowledge discovery and automated recovery planning. We base our discussion on an application scenario for recovery from border router failure to maintain optimized configuration of outbound inter-domain traffic.