A declarative approach for secure and robust routing

The Internet consists of a large number of autonomous systems (ASes) that exchange routing information using the border gateway protocol (BGP). Each AS applies local policies for selecting routes and propagating routes to others, with important implications for the reliability and stability of the global system. In and of itself, BGP does not ensure that every pair of hosts can communicate. In addition, routing policies are not guaranteed be safe, and may cause protocol divergence. Backup routing is often used to increase the reliability of the network under link and router failures, at the possible expense of safety. This paper presents a general model for backup routing that increases network reliability while allowing each AS to apply local routing policies that are consistent with the commercial relationships it has with its neighbors. In addition, our model is inherently safe in the sense that the global system remains safe under any combination of link and router failures. Our model and the proof of inherent safety are cast in terms of the stable paths problem, a static formalism that captures the semantics of interdomain routing policies. Then, we describe how to realize our model in BGP with locally-implementable routing policies. To simplify the specification of local policies, we propose a new BGP attribute that conveys the avoidance level of a route. We also describe how to realize these policies without modification to BGP by using the BGP community attribute.

Internet traffic is highly dynamic and difficult to predict in current network scenarios. This makes of Traffic Engineering (TE) a very challenging task for network management and resources optimization. We study the problem of Intradomain Routing Optimization under this traffic uncertainty. Recent works have proposed robust optimization techniques to tackle the problem, conceiving the Robust Routing (RR) approach. RR copes with traffic uncertainty in an off-line preemptive fashion, computing a single static routing configuration that is optimized for traffic variations within some predefined uncertainty set. Despite achieving routing reliability with relatively low performance loss, RR presents various drawbacks and conception problems as it is currently proposed. This paper brings insight into the different Robust Routing shortcomings, introducing new mechanisms that improve previous proposals and alleviate these problems. Among others, we propose and evaluate new optimization objectives to attain better global performance from an end-to-end quality of service perspective.

Traffic engineering (TE) has become a challenging mechanism for network management and resources optimization due to uncertain and difficult to predict traffic patterns. Recent works have proposed robust optimization techniques to cope with uncertain traffic, computing a stable routing configuration that is immune to demand variations within certain uncertainty set. However, using a single routing configuration for longtime periods can be highly inefficient. Even more, the presence of abnormal and malicious traffic has magnified the network operation problem, claiming for solutions which not only deal with traffic uncertainty but also allow to detect and identify faulty traffic to take the appropriate countermeasures. In this paper, we introduce the Reactive Robust Routing (RRR) for TE, an approach that combines both proactive and reactive techniques to tackle the problem. Based on expected traffic patterns, we adapt the uncertainty set and build a multi-hour yet robust routing scheme that outperforms the stable robust approach. For the case of anomalous and unexpected traffic, we propose a fast anomaly detection/isolation algorithm to detect and localize abrupt changes in traffic flows and decide routing changes. This algorithm is optimal in the sense that it minimizes the decision delay for a given mean false alarm rate and false isolation probability. We validate these proposals using real data from two different backbone networks and we show how the RRR can handle uncertain and highly dynamic traffic in an automatic fashion, simplifying network operation.

Interdomain routing stitches the disparate parts of the Internet together, making protocol stability a critical issue to both researchers and practitioners. Yet, researchers create safety proofs and counterexamples by hand and build simulators and prototypes to explore protocol dynamics. Similarly, network operators analyze their router configurations manually or using homegrown tools. In this paper, we present a comprehensive toolkit for analyzing and implementing routing policies, ranging from high-level guidelines to specific router configurations. Our Formally Safe Routing (FSR) toolkit performs all of these functions from the same algebraic representation of routing policy. We show that routing algebra has a natural translation to both integer constraints (to perform safety analysis with SMT solvers) and declarative programs (to generate distributed implementations). Our extensive experiments with realistic topologies and policies show how FSR can detect problems in an autonomous system's (AS's) iBGP configuration, prove sufficient conditions for Border Gateway Protocol (BGP) safety, and empirically evaluate convergence time.

Mobile Ad hoc Network (MANET) is a kind of wireless ad-hoc network, and is a self-configuring network of mobile routers (and associated hosts) connected by wireless links - the union of which forms an arbitrary topology. The routers are free to move randomly and organize themselves arbitrarily, thus the network's wireless topology may change rapidly and unpredictably. Such a network may operate in a standalone fashion, or may be connected to the larger Internet. There are various routing protocols available for MANETs. The most popular ones are DSR, AODV and DSDV. This paper examines two routing protocols for mobile ad hoc networks- the Destination Sequenced Distance Vector (DSDV and the Ad hoc On- Demand Distance Vector routing (AODV). Generally, the routing algorithms can be classified into Reactive and Proactive. A Hybrid algorithm combines the basic properties of reactive and proactive into one. The proposed approach is a novel routing pattern based on Ant Colony Optimization and Multi Agent System. This pattern integrates two different algorithms together and helps to get optimum routes for a particular radio range. The approaches used here are Ant Colony Optimization (ACO) and Multi Agent System (MAS). The proposed integrated approach has a relatively short route establishment time while using a small number of control messages which makes it a scalable routing approach. The overhead of this routing approach will be inexpensive and also will enable to have an alternate route during route failure. This proposed route finding scheme in order to provide high connectivity of nodes, will minimize the route discovery latency and the end-to-end delay.

Geographic routing has been considered as an attractive approach for resource-constrained wireless sensor networks (WSNs) since it exploits local location information instead of global topology information to route data. However, this routing approach often suffers from the routing hole (i.e., an area free of nodes in the direction closer to destination) in various environments such as buildings and obstacles during data delivery, resulting in route failure. Currently, existing geographic routing protocols tend to walk along only one side of the routing holes to recover the route, thus achieving suboptimal network performance such as longer delivery delay and lower delivery ratio. Furthermore, these protocols cannot guarantee that all packets are delivered in an energy-efficient manner once encountering routing holes. In this paper, we focus on addressing these issues and propose an energy-aware dual-path geographic routing (EDGR) protocol for better route recovery from routing holes. EDGR adaptively utilizes the location information, residual energy, and the characteristics of energy consumption to make routing decisions, and dynamically exploits two node-disjoint anchor lists, passing through two sides of the routing holes, to shift routing path for load balance. Moreover, we extend EDGR into threedimensional (3D) sensor networks to provide energy-aware routing for routing hole detour. Simulation results demonstrate that EDGR exhibits higher energy efficiency, and has moderate performance improvements on network lifetime, packet delivery ratio, and delivery delay, compared to other geographic routing protocols in WSNs over a variety of communication scenarios passing through routing holes. The proposed EDGR is much applicable to resource-constrained WSNs with routing holes.

Quality of service (QoS) is gaining more and more importance in today's networks. We present a fully decentralized and self-organizing approach for QoS routing and Traffic Engineering in connection oriented networks, e.g. MPLS networks. Based on reinforcement learning the algorithm learns the optimal routing policy for incoming connection requests while minimizing the blocking probability. In contrast to other approaches our method does not rely on predefined paths or LSPs and is able to optimize the network utilization in the presence of multiple QoS restrictions like bandwidth and delay. Moreover, no additional signaling overhead is required. Using an adaptive neural vector quantization technique for clustering the state space a considerable speed-up of learning the routing policy can be achieved. In different experiments we are able to show that our approach performs better than classical approaches like Widest Shortest Path routing (WSP).

The border gateway protocol, BGP, is currently the only interdomain routing protocol employed on the Internet. As required of any interdomain protocol, BGP allows policy-based metrics to override distance-based metrics and enables each autonomous system to independently define its routing policies with little or no global coordination. Varadhan et al. (1996) have shown that there are collections of routing policies that together are not safe in the sense that they can cause BGP to diverge. That is, an unsafe collection of routing policies can result in some autonomous systems exchanging BGP routing messages indefinitely, without ever converging to a set of stable routes. In this paper we present sufficient conditions on routing policies that guarantee BGP safety. We use a new formalism, called the simple path vector protocol (SPVP), that is designed to capture the underlying semantics of any path vector protocol such as BGP. We identify a certain circular set of relationships between routing policies at various autonomous systems that we call a dispute cycle. We show that systems with no dispute cycles are guaranteed to be safe. While these include systems whose policies are consistent with shortest paths under some link metric, the class of systems with no dispute cycles is strictly larger.

In this paper we propose a new algorithm for routing in mobile survivable networks, based on the combination of position-based routing concepts and fault-tolerant routing techniques in computer networks. By using a combination of these two concepts we achieve a simplified way of localizing routing overhead while at the same time we improve the operational effectiveness of the position-based routing approaches by alleviating some of the drawbacks associated with them, such as routing deadlock occurrences, and therefore creating a robust and fault tolerant routing strategy.

In this paper, we investigate how robust and flexible solutions of a number of stochastic variants of the capacitated vehicle routing problem can be obtained. To this end, we develop and discuss a method that combines a sampling based approach to estimate the robustness or flexibility of a solution with a metaheuristic optimization technique. This combination allows us to solve larger problems with more complex stochastic structures than traditional methods based on stochastic programming. It is also more flexible in the sense that adaptation of the approach to more complex problems can be easily done. We explicitly recognize the fact that the decision maker’s risk preference should be taken into account when choosing a robust or flexible solution and show how this can be done using our approach.

An integrated scenario-based approach for robust aircraft routing, crew pairing and re-timing

By tweaking the BGP configurations, the network operators are able to express their interdomain routing preferences, designed to accommodate a myriad goals. Given the complex interactions between policies in the Internet, the origin AS by itself cannot ensure that only by configuring a routing policy it can also achieve the anticipated results. Moreover, the definition of routing policies is a complicated process, involving a number of subtle tuning operations prone to errors. In this paper, we propose the BGP Visibility Scanner which allows network operators to validate the correct implementation of their routing policies, by corroborating the BGP routing information from approximatively 130 independent observation points in the Internet. We exemplify the use of the proposed methodology and also perform an initial validation for the BGP Visibility Scanner capabilities through various real operational use cases.

A Modified Border Gateway Protocol (MBGP) has been proposed towards achieving faster BGP convergence in the Internet following link/router/ network failures. MBGP adopts the overall strategy of distributed fault detection-cum-identification, fault notification and rediscovery-cum-readvertisement of valid routes. In the assumed simplified model of the Internet, the sole MBGP router in each autonomous system (AS) identifies any failed component using the novel concept of special neighbors and notifies the identity of the failed component to all the MBGP routers in the Internet. Six new messages, including a query-response message pair and four permanent withdrawal messages, have been proposed in MBGP, without changing the BGP message format. The path exploration problem is significantly reduced because some failures cause no path exploration, the others do but only in a small number of nearby routers and, finally, no invalid messages are ever exchanged. Simulation studies have demonstrated significantly faster convergence of MBGP over BGP.KeywordsBGP ConvergenceSlow Convergence in BGPFast BGP ConvergenceLink or Router Failure in InternetPath Exploration in BGPModified BGPSpecial Neighbors

We present the demonstration of a comprehensive toolkit for analyzing and implementing routing policies, ranging from high-level guidelines to specific router configurations. Our Formally Safe Routing (FSR) toolkit performs all of these functions from the same algebraic representation of routing policy. We show that routing algebra has a very natural translation to both integer constraints (to perform safety analysis using SMT solvers) and declarative programs (to generate distributed implementations). Our demonstration with realistic topologies and policies shows how FSR can detect problems in an AS's iBGP configuration, prove sufficient conditions for BGP safety, and empirically evaluate convergence time.

We use a realistic interdomain routing experiment platform to conduct real-time attack and defense exercises for training purposes. Our interdomain routing experiment platform integrates open-source router software, real-time network simulation, and light-weight machine virtualization technologies, and is capable of supporting realistic large-scale routing experiments. The network model used consists of major autonomous systems connecting Swedish Internet users with realistic routing configurations derived from the routing registry. We conduct a series of real-time security exercises on this routing system to study the consequence of intentionally propagating false routing information on interdomain routing and the effectiveness of corresponding defensive measures. We describe three kinds of simplistic BGP attacks in the context of security exercises designed specifically for training purposes. While an attacker can launch attacks from a compromised router by changing its routing policies, administrators will be able to observe the adverse effect of these attacks and subsequently apply appropriate defensive measures to mitigate their impact, such as installing filtering rules. These exercises, all carried out in real time, demonstrate the feasibility of routing experiments using the real-time routing experiment platform.