Networking Seminar 2011

Tue, 06/14/2011 - 11:15 by Benoit Donnet • Categories:

The IP Networking Lab (INL), is organizing a 2-days seminar in July 2011

The seminarl will be held between July, 6th and July 7th in Louvain-la-Neuve, Belgium.


July, 6th

Welcome Speech
Speaker: Prof. Olivier Bonaventure (Université catholique de Louvain)

Understanding Operational Routing (Part 1) - [Slides]
Speaker: Prof. Geoffrey Xie (Naval Post Graduate School)
Abstract: Over the last 30 years the networking community has made considerable advances in the understanding of Internet routing protocols. However, recent empirical studies reveal that operational practices for routing have outpaced the theory in at least three fundamental ways: First, routing designs in the real world, particularly those of large enterprise networks, have much more complex structures than the conventional 2-level BGP/IGP hierarchy. Second, the connecting primitives of "administrative distance" "route redistribution", introduced by router vendors to allow merging multiple network domains that run independent routing protocol instances, are used to support critical design goals that cannot be fulfilled by routing protocols alone. Third, "route aggregation" is becoming an important primitive of routing design.

In this talk, I present a comprehensive and systematic study of these operational routing primitives. First, I show that the primitives are prone to a wide range of anomalies, including forwarding loops, blackholes, and persistent route oscillations. Then, I introduce new analytical models to uncover the root causes of these anomalies, and furthermore, illustrate the challenges of debugging them earlier from router configuration data. Finally, I propose both configuration guidelines and potential clean-slate design solutions to address the problem.


Understanding Operational Routing (Part 2) - [Slides]
Speaker: Prof. Geoffrey Xie (Naval Postgraduate School)

Coffee Break

Evolving Route-Reflection Hierarchies: Why, When, and How
Speaker: Stefano Vissicchio (Universita' Roma Tre)
Abstract:nternal BGP (iBGP) sessions play a key role in large ISP networks as they are used to disseminate all the interdomain routes received by the border routers. Unfortunately, the optimal organization of these iBGP sessions depends on many factors that evolve with the network. When new requirements appear or when router capabilities change, the network operators often need to redesign iBGP Route-Reflection hierarchy of their networks. In this talk, we address the problem of seamlessly evolving a Route-Reflection hierarchy. In particular, we show that long-lasting routing anomalies, such as loss of connectivity, suboptimal egress point selection, traffic deflection and forwarding loops, can arise when iBGP configuration is changed. We describe different methodologies that can be adopted in specific scenarios, and what are the main trade-offs they achieve. We illustrate the results of some experiments performed on a tier1 ISP network.

Seamless Network-Wide IGP Migrations
Speaker: Laurent Vanbever (Université catholique de Louvain)
Abstract:Network-wide migrations of a running network, such as the replacement of a routing protocol or the modification of its configuration, can improve the performance, scalability, manageability, and security of the entire network. However, such migrations are an important source of concerns for network operators as the reconfiguration campaign can lead to long and service-affecting outages. In this talk, we propose a methodology which addresses the problem of seamlessly modifying the configuration of commonly used link-state Interior Gateway Protocols (IGP). We illustrate the benefits of our methodology by considering several migration scenarios, including the addition or the removal of routing hierarchy in an existing IGP and the replacement of one IGP with another. We prove that a strict operational ordering can guarantee that the migration will not create IP transit service outages. Although finding a safe ordering is NP-complete, we describe techniques which efficiently find such an ordering and evaluate them using both realworld and inferred ISP topologies. Finally, we describe the implementation of a provisioning system which automatically performs the migration by pushing the configurations on the routers in the appropriate order, while monitoring the entire migration process.


July, 7th

Towards Systematic Design of Enterprise Networks - [Slides]
Speaker: Prof. Geoffrey Xie (Naval Postgraduate School)
Abstract: Enterprise networks are important, with size and complexity even surpassing carrier networks. In this talk, I present a systematic design approach to accomplish two key tasks of enterprise design: virtual local area networks (VLANs) and reachability control. The focus on these tasks is due to their complexity, prevalence, and time-consuming nature. In particular, I detail three aspects of the approach. First, I show how the design tasks may be formulated in terms of network-wide performance, security, and resilience requirements. The formulations capture the correctness and feasibility constraints on the design, and they model each task as one of optimizing desired criteria subject to the constraints. The optimization criteria may further be customized to meet operator-preferred design strategies. Second, I describe a set of algorithms to solve the problems that have been formulated. Third, I demonstrate the practicality and value of the systematic design approach through results from a set of validation experiments on a large-scale campus network with hundreds of routers and VLANs.

Coffee Break

Internet Topology Discovery - [Slides]
Speaker: Dr. Benoit Donnet (Université catholique de Louvain/FNRS)
Abstract: Since the beginning of the nineties, the Internet has undergone impressive growth. This growth can be appreciated in terms of the equipment, such as routers and links, that has been added, as well as in the numbers of users and the value of commerce that it supports. In parallel to this expansion, over the past decade the networking research community has shown a growing interest in discovering and analyzing the internet topology. Some researchers have developed tools for gathering network topology data while others have tried to understand and model the Internet's properties. These efforts have brought us to a crucial juncture for toplogy measurement infrastructures: while, previously, these were both small (in terms of number of measurement points) and monolithic, we are starting to see the deployment of large-scale distributed systems composed of hundreds or thousands of monitors. As we look forward to this next generation of systems, we take stock of what has been achieved so far. In this survey, we discuss past and current mechanisms for discovering the internet topology at various levels: the IP interface, the router, and the AS level. In addition to discovery techniques, we provide insights into some of the well-known properties of the Internet topology.


Primitives for Active Internet Topology Mapping: Toward High-Frequency Characterization - [Slides]
Speaker: Prof. Geoffrey Xie (Naval Postgraduate School)
Abstract:Current large-scale topology mapping systems require multiple days to characterize the Internet due to the large amount of probing traffic they incur. The accuracy of maps from existing systems is unknown, yet empirical evidence suggests that additional fine-grained probing exposes hidden links and temporal dynamics. In this talk, through longitudinal analysis of data from the Archipelago and iPlane systems, in conjunction with additional active probing, I examine how to shorten Internet topology mapping cycle time. In particular, I present three discriminatory primitives that leverage external knowledge (e.g., common subnetting structures) and data from prior cycle(s) to guide the selection of probed destinations and the assignment of destinations to vantage points. The Interface Set Cover (ISC) algorithm generalizes previous dynamic probing work. Crucially, ISC runs across probing cycles to minimize probing while detecting load balancing and reacting to topological changes. To maximize the information gain of each trace, the Subnet Centric Probing technique selects destinations more likely to expose their network’s internal structure. Finally, the Vantage Point Spreading algorithm uses network knowledge to increase path diversity to destination ingress points.

Coffee Break

BGP Path diversity, issues and solutions - [Slides]
Speaker: Dr. Pierre François (Université catholique de Louvain/FNRS)
Abstract: In this talk, we will discuss a main evolution of BGP aimed at improving BGP path diversity in Internet service provider networks. We will see how BGP route reflection can lead to sub-optimal, slowly converging, and sometimes incorrect routing due to the lack of path visibility that it introduces. We will then compare various approaches to tackle this problem, and we will review the IETF activities related to this evolution of BGP. As a second part, we will see how lack of path diversity can be created and exploited at the inter-domain level to violate the policies of internet service providers. We will review the potential solutions to this problem, and advocate for a simple monitoring-based detection of policy violations rather than a technical enforcement of their respect.

Internet Exchanges and Route Servers - [Slides]
Speaker: Elisa Jasinska (Limelight Networks)
Abstract: TBA


Summer School Location and Accomodation

Université catholique de Louvain, Louvain-la-Neuve (south of Brussels)
The conference will be held in the "Auditoires Sainte Barbe", in room Barb00.

The building is located here.

Warning: Be careful, Leuven ("Louvain" in french) is not Louvain la Neuve. Generally, Louvain la Neuve is denoted "Louvain la Neuve Université" in train stations.

Detail for reaching Louvain-la-Neuve are available here.

The Hotel Mercure is the closest hotel to the Summer School Location. If you prefer, you can book a room in a hotel in Brussels, but this requires to take the train (roughly 1 hour) in the morning and in the evening.


Attending the Summer School is free of charge. However, for logistical reasons, attendees should register by filling the following form: