Abstract

This paper proposes an integrated network management framework for inter-domain 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, inter-domain routing changes and link failures. The objective is to keep the inter-domain link utilization balanced under any of these changes while reducing service disruptions and reconfiguration overheads. Simulation results demonstrate that the proposed framework can achieve better load balancing with less service disruptions and re-configuration overheads in comparison to alternative approaches. Document type: Part of book or chapter of book

Abstract

The inflexibility and rigidity of the current networking systems in light of the growing number of computing devices that connected to the Internet has led to the need of a new generation of computer networks. In this context, software-defined network has recently emerged as one of the most recognisable solutions to facilitate the network management and decrease the complexity through detaching the control layer from network appliances. Since, each new technology accompanied with new issues and concerns, one of the main challenges that facing the SDNs is the fault tolerance and resilience. Although there are a numerous of studies that have discussed this issue, the after failure repair scenario is remained unclear and have not addressed well yet. For this reason, we specify this paper as a step forward to address the issue of routing changes, which is important for utilising the optimal paths after failure repair. We produced a new network model as well as a compatible framework with SDN architecture to fulfil the routing changes activity. The consequence is estimated based on an analytical model and finally, a case study example is provided in order to conceptualise the concept. Document type: Part of book or chapter of book

Abstract

State Estimation is an intrinsic element of many network manage-ment systems, like Power Distribution Networks and Water Distribution Networks, where its implementation not only facilitates real-time online monitoring with better observability, but it also enables an advanced control with improved system security. This paper presents a new technique based on State Estimation to address some general shortcomings of the current Active Queue Management schemes such as RED and discusses potential issues in TCP networks in order to achieve better performance. Document type: Part of book or chapter of book

Abstract

Traffic Engineering (TE) approaches are increasingly impor- tant in network management to allow an optimized configuration and resource allocation. In link-state routing, the task of setting appropriate weights to the links is both an important and a challenging optimization task. A number of different approaches has been put forward towards this aim, including the successful use of Evolutionary Algorithms (EAs). In this context, this work addresses the evaluation of three distinct EAs, a single and two multi-objective EAs, in two tasks related to weight setting optimization towards optimal intra-domain routing, knowing the network topology and aggregated traffic demands and seeking to mini- mize network congestion. In both tasks, the optimization considers sce- narios where there is a dynamic alteration in the state of the system, in the first considering changes in the traffic demand matrices and in the latter considering the possibility of link failures. The methods will, thus, need to simultaneously optimize for both conditions, the normal and the altered one, following a preventive TE approach towards robust configurations. Since this can be formulated as a bi-objective function, the use of multi-objective EAs, such as SPEA2 and NSGA-II, came nat- urally, being those compared to a single-objective EA. The results show a remarkable behavior of NSGA-II in all proposed tasks scaling well for harder instances, and thus presenting itself as the most promising option for TE in these scenarios. Document type: Part of book or chapter of book

Abstract

In this paper, we present an analysis on optimization and risk management in Communication Networks (CNs). The model is proposed for offline traffic engineering optimization, which takes a centralized view of bandwidth allocation, performance control, and risk control of network profit shortfall. First, we introduce a linear penalty cost in the CN optimization model and derive the optimal bandwidth capacity with the penalty cost. Then, we use the mean-variance approach to analyze the profit shortfall risk in CNs. Finally, numerical results are shown to reveal the impact of the penalty cost on the CNs performance. Document type: Part of book or chapter of book

Abstract

One of the key issues in mobile communication system is how to predict the number of calls per each cell. It is an important parameter and usually assumed as random Poisson value. For effective management of cellular network, the average number of calls should be traced and the changes in the numbers need to be promptly detected. In this paper we propose an algorithm detecting the changes in the behavior of the users using the technique proposed for point-of-change problem based only on the number of call arrivals. Computer simulation reveals that the proposed method can effectively detect the discord, and the developed model is very accurate as showing mostly less than 1% differences. Document type: Part of book or chapter of book

Abstract

Date of Conference: 1-3 Oct. 2003 Conference name: Proceedings of the 3rd IEEE Workshop on IP Operations & Management (IPOM 2003) We propose a novel traffic engineering architecture for IP networks with multiprotocol label switching (MPLS) backbones. In this architecture, two (primary and secondary) label switched paths (LSPs) are established among every pair of IP routers located at the edge of an MPLS cloud. Traffic between a source-destination pair is then split between the primary and secondary LSPs using an ABR-like explicit-rate feedback gathered from the network. Taking into consideration the packet reordering effect of packet-based load balancing schemes, we propose a novel traffic splitting mechanism that operates on a per-flow basis. We show, using a variety of scenarios, that deploying flow-based multipath traffic engineering not only provides significantly and consistently better throughput than that of a single path, but is also void of any packet reordering. © 2003 IEEE.

Abstract

In this work, an user friendly software application is proposed, built on top of a network optimization framework, aiming to make traffic engineering an easier task for IP network administrators. This framework was developed in the Center of Computer Science and Technology (CCTC) of the University of Minho and allows the improvement of quality of service levels in TCP/IP based networks, by configuring the routing weights of link-state protocols, such as OSPF. This goal is achieved mainly using Evolutionary Algorithms as the optimization engines, while networks are represented using graph-based mathematical models. These methods allow the optimization of distinct cost functions, using penalties that take into account several measures of network performance such as network congestion and average end-to-end delays. The main goal of this work is to create a structured graphical user interface to support the optimization framework, enabling the user to simulate the effects of diferente OSPF settings, to obtain highly optimized configurations and to compare different weight setting optimization methods.

Abstract

High-rate large-sized (α) flows have adverse effects on delay-sensitive flows. Research-and- education network providers are interested in identifying such flows within their networks, and directing these flows to virtual circuits. To achieve this goal, a design was proposed for a hybrid network traffic engineering system (HNTES) that would run on an external server, gather NetFlow records from routers, analyze these records to identify α-flow source/destination address prefixes, configure firewall filter rules at ingress routers to extract future α flows and redirect them to pro- visioned virtual circuits. This thesis presents an evaluation of this HNTES design using NetFlow records collected over a 7-month period from four ESnet routers. The results show that the HNTES effectiveness was above 90% for NetFlow records collected at edge routers, which corresponded to file downloads from Department of Energy (DOE) laboratories, while the effectiveness was lower for peering routers whose NetFlow records corresponded to file uploads. With further investigation, we found that uploads were less frequent and involved fewer source/destination pairs than downloads. The thesis also describes an algorithm for characterizing the size, duration, average rate, and frequency of α flows, from NetFlow records. The algorithm was validated using independently collected usage logs from application servers. This algorithm can be used in a network management system for providers interested in these types of flows, such as research-and-education network providers whose customers move large scientific datasets. We executed the algorithm on the same NetFlow records used in the HNTES evaluation. Flows moving datasets as large as 811 GB and at rates as high as 5.7 Gbps were observed. Some source-destination pairs were found to repeatedly create α flows. An analysis of the rates of the 1596 repeated α flows created by one pair showed considerable variance, with minimum rate of 100 Mbps, maximum rate of 536 Mbps, and a coefficient of variation of 30%.

Abstract

We present the TOTEM open source Traffic Engineering (TE) toolbox and a set of TE methods that we have designed and/or integrated. These methods cover intra-domain and inter-domain TE, IP-based and MPLS-based TE. They are suitable for network optimisation, better routing of traffic for providing QoS, load balancing, protection and restoration in case of failure, etc. The toolbox is designed to be deployed as an on-line tool in an operational network, or used off-line as an optimisation tool or as a traffic engineering simulator. Peer Reviewed