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Various traffic engineering techniques are used to control the flow of IP packets inside large ISP networks. However, few techniques have been proposed to control the flow of packets between domains. In this paper, we focus on the needs of stub ISPs that compose 80% of the global Internet. We first describe the typical traffic pattern of such a stub ISP. Then we briefly describe the methods that those ISPs currently use to engineer their interdomain traffic. We focus on the control of the incoming traffic and show the increasing utilization of the BGP Community attribute and discuss the limitations of this approach. We then propose the redistribution communities as a deployable method to control the flow of the incoming interdomain traffic. We implement those redistribution communities in zebra and evaluate its performance. (C) 2003 Elsevier B.V. All rights reserved.

Traffic engineering is performed by means of a set of techniques that can be used to better control the flow of packets inside an IP network. We discuss the utilization of these techniques across interdomain boundaries in the global Internet. We first analyze the characteristics of interdomain traffic on the basis of measurements from three different Internet service providers and show that a small number of sources are responsible for a large fraction of the traffic. Across interdomain boundaries, traffic engineering relies on a careful tuning of the route advertisements sent via the border gateway protocol. We explain how this tuning can be used to control the flow of incoming and outgoing traffic, and identify its limitations.

All equipments attached to the Internet are configured with one or several IP addresses. Most hosts are able to automatically request (e.g., from a DHCP server) or discover (e.g., by using stateless autoconfiguration) the IP address that they should use. This simplifies the configuration and the management of hosts. Unfortunately, these techniques do not apply on routers whose IP addresses and subnet prefixes for their directly attached LANs still need to be manually configured. This utilization of manual configuration is error-prone and a frequent source of errors. It is also one of the reasons why IP address renumbering is so difficult with both IPv4 and IPv6. In this paper, we propose a new address block allocation and distribution protocol that has been designed to be both secure and efficient. We first summarize the main requirements of an address block allocation mechanism. We then describe the operation of our proposed mechanism. Finally, we demonstrate the efficiency of our protocol by simulations. Anglais

WiFi technology has become the preferable form for mobile users to connect to the Internet. The growing popularity of WiFi-enabled devices and the increasing number of WiFi networks guarantees that this trend will continue in the future. Since a single network provider is usually not able to ensure WiFi coverage for its own users across many geographic locations the WiFi roaming technology appears to be the promising solution. A special attention upon the practical deployment of WiFi roaming should be paid to possible threats coming from the misuse of technology. In this light we analyze various legal implications that might become relevant due to the deployment of WiFi roaming and discuss several risks and problems related to the security during the establishment of roaming connections between mobile devices and the Internet. Anglais

In a few years, the Internet has quickly evolved from a research network connecting a handful of users to the largest distributed system ever built. The Internet connects more than 20,000 Autonomous Systems (ASs) which are administratively independent networks. While the initial Internet was designed to provide a best-effort connectivity among these ASs, there is nowadays a growing trend to deploy new services such as Voice/Video over IP or VPNs. To support these emergent services, ASs need to better engineer their Internet traffic. Traffic Engineering encompasses several goals such as better spreading the traffic load inside a network and obtaining better end-to-end performance (lower latency or higher bandwidth). Engineering the traffic inside a single AS is feasible and pretty well understood. To the opposite, interdomain traffic engineering is still a difficult problem. The main issue comes from the current Internet routing architecture, articulated around the Border Gateway Protocol (BGP). BGP propagates a subset of the Internet topology for scalability and stability reasons and does not optimize a single global objective. This limits the control each AS has on its routing and has dramatic implications for interdomain traffic engineering. In this thesis, we evaluate the primitive BGP-based routing control mechanisms. For this purpose, we designed and implemented a new approach for modeling BGP on large Internet-scale network topologies. Finally, to overcome the limitations of BGP in terms of routing control, we propose Virtual Peerings, a new mechanism based on a combination of BGP and IP tunneling. We apply Virtual Peerings to solve various interdomain traffic engineering problems such as balancing the load of Internet traffic received by an AS or decreasing the end-to-end latency of Internet paths. (FSA 3)--UCL, 2006

During the last years, MultiProtocol Label Switching (MPLS) has been deployed by most large Service Providers (SP). The main driver for MPLS deployment is the ability to provide new services with stringent Service Level Agreements (SLAs) such as layer-2 and layer-3 Virtual Private Networks (VPNs) as well as Voice and Video over IP. Most of these services are already deployed inside single SP networks. However, customers now require world-wide VPN and VoIP services. Therefore, SPs need to collaborate to offer these services across multiple SP networks. Inside a single SP network, each node usually knows the complete topology of the network with the load and delay of all the links. Based on this information, each router is able to compute constrained paths toward any other router inside the SP network. Then, it can establish a connection and reserve resources along the computed path with the Resource reSerVation Protocol (RSVP-TE). However, when services with stringent requirements must cross multiple SP networks the computation of the path becomes a problem. Routers in different SP networks exchange routing information by using the Border Gateway Protocol (BGP). BGP provides reachability information. It does not distribute complete topology, delay and bandwidth information. One way to provide guaranteed services crossing different SPs is to delegate the computation of the paths to a Path Computation Element (PCE) that learns the topology of the different SPs. However, this requires that SPs reveal information that they usually consider confidential, their topology. In this thesis, we perform active measurements to show the difficulty to engineer the interdomain traffic with BGP. MPLS together with RSVP-TE provide much more control on the traffic. We define extensions to RSVP-TE for the protection of inter-AS MPLS paths. The aim is to be able to provide the same service guarantees as inside a domain while keeping the internal topology of SPs confidential, as required by SPs. We propose and evaluate distributed techniques relying on PCEs for the computation of interdomain constrained paths respecting the latter confidentiality requirement. (FSA 3)--UCL, 2006

Internet connectivity takes a strategic importance for a growing number of companies. Therefore, for reliability and performance reasons, many Internet service providers and corporate networks connect to at least two providers, a practice called multihoming. However, the current multihoming mechanism contributes to the explosive growth of the Internet routing tables. This growth has major implications for routers on storage requirements, protocol overhead and stability, and forwarding performance. As a consequence, the traditional way to be multihomed in IPv4 is prevented in the next generation IPv6 Internet. Many approaches for IPv6 multihoming were proposed, with little consideration for traffic engineering aspects. The aim of the thesis is to bridge this gap. The thesis investigates the way to best provide traffic engineering for IPv6 multihomed sites. It first demonstrates that Host-Centric multihoming, the foreseen approach for IPv6 multihoming, is the most promising in terms of fault-tolerance and traffic engineering capabilities. Compared to traditional multihoming approaches, our simulation results show that Host-Centric IPv6 multihomed sites are able to obtain lower delays by leveraging the path diversity that underlies the Internet. Unfortunately, no traffic engineering mechanism is available for this multihoming approach. Therefore, this thesis next presents a technique to effectively use the multiple interdomain paths that exist between multihomed sites. The proposed mechanism allows the multihomed sites to control how their flows are distributed over the links with their providers. The mechanism is able to take into account complex and very dynamic routing policies. Finally, the thesis proposes the use of synthetic coordinates as a scalable and efficient way to help hosts in selecting the interdomain paths with the lowest delays. Experimental results with real measurements show that this mechanism allows sites to avoid all paths with really bad delays, and to most often select the lowest delay path. (FSA 3)--UCL, 2005

Many Internet Service Providers tune the configuration of the Border Gateway Protocol on their routers to control their traffic. Content providers often need to control their outgoing traffic while access providers need to control their incoming traffic. We show, by means of measurements and simulations, that controlling the flow of the incoming interdomain traffic is a difficult problem. For this purpose, we first rely on detailed measurements to show the limitations of AS-Path prepending. Then, we show by using large-scale simulations that the difficulty of controlling the flow of the incoming traffic lies in the difficulty of predicting which BGP route will be selected by distant Autonomous Systems (ASs).

We describe and analyse in details the various factors that influence the convergence time of intradomain link state routing protocols. This convergence time reflects the time required by a network to react to the failure of a link or a router. To characterise the convergence process, we first use detailed measurements to determine the time required to perform the various operations of a link state protocol on currently deployed routers. We then build a simulation model based on those measurements and use it to study the convergence time in large networks. Our measurements and simulations indicate that sub-second link-state IGP convergence can be easily met on an ISP network without any compromise on stability.

This thesis discusses the implications of the traffic characteristics on interdomain traffic engineering with BGP. We first provide an overview of the interdomain traffic control problem. Then, we present results concerning the characteristics of the interdomain traffic, based on the analysis of real traffic traces gathered from non-transit ASes. We discuss the implications of the topological properties of the traffic on interdomain traffic engineering. Based on this knowledge of the traffic characteristics, we go on to study the complexity of designing interdomain traffic engineering techniques by defining the problem as an optimization problem. We show that designing traffic engineering techniques is possible but that several issues inherent to the current interdomain architecture make the task complex. Finally, we evaluate the current state-of-the-art of interdomain traffic engineering and discuss how we envision its future. (FSA 3)--UCL, 2004

Once multihomed, an IPv6 site usually wants to engineer its interdomain traffic. We propose that IPv6 multihomed hosts inquire a so called "Name, Address and ROute System" (NAROS) to determine the source and destination addresses to use to contact a destination node. By selecting these addresses, the NAROS server roughly determines the routing. It thereby provides features like traffic engineering and fault tolerance, without transmitting any BGP advertisement and without impacting on the worldwide routing table size. The performance of the NAROS server is evaluated by using trace-driven simulations. We show that the the load on the NAROS server is reasonable and that we can obtain good load-balancing performances.

With Intradomain Routing Protocols, by optimizing the configuration (Trafic Engineering -TE) of link weights, operators can significantly improve the load of their links, which is known to be an NP-hard problem. Another emerging issue for ISP networks is the fast restoration of IP services in the case of failures. Recently, Fast Reroute techniques have been proposed for pure IP networks. The Loop Free Alternates (LFA) is one of the most promising technique. An LFA for a router A, for a destination d, is a neighbor C of A which does not use A to reach d, so that A can prepare itself to directly reroute the traffic destined to d along its link with C upon the failure of the link that A is using to reach d. Our objective is to provide a TE technique that takes the coverage of LFAs into account during the network resource usage optimization. Constraint Programming and Constraint-Based Local Search are well suited for solving such complex combinatorial problems. Especially in COMET, some classical problems can be modeled in only about a dozen lines of code. So, we have chosen a local search algorithm implemented in COMET for solving our traffic engineering problem.