Where’s Waldo? practical searches for stability in iBGP

Copyright © 2008 IEEEWhat does a child’s search of a large, complex cartoon for the eponymous character (Waldo) have to do with Internet routing? Network operators also search complex datasets, but Waldo is the least of their worries. Routing oscillation is a much greater concern. Networks can be designed to avoid routing oscillation, but the approaches so far proposed unnecessarily reduce the configuration flexibility. More importantly, apparently minor changes to a configuration can lead to instability. Verification of network stability is therefore an important task, but unlike the child’s search, this problem is NP hard. Until now, no practical method was available for large networks. In this paper, we present an efficient algorithm for proving stability of iBGP, or finding the potential oscillatory modes, and demonstrate its efficacy by applying it to the iBGP configuration of a large Tier-2AS.Ashley Flavel, Matthew Roughan, Nigel Bean and Aman Shaik

Study of BGP Convergence Time

Border Gateway Protocol (BGP), a path vector routing protocol, is a widespread exterior gateway protocol (EGP) in the internet. Extensive deployment of the new technologies in internet, protocols need to have continuous improvements in its behavior and operations. New routing technologies conserve a top level of service availability. Hence, due to topological changes, BGP needs to achieve a fast network convergence. Now a days size of the network growing very rapidly. To maintain the high scalability in the network BGP needs to avoid instability. The instability and failures may cause the network into an unstable state, which significantly increases the network convergence time. This paper summarizes the various approaches like BGP policies, instability, and fault detection etc. to improve the convergence time of BGP

On Compact Routing for the Internet

While there exist compact routing schemes designed for grids, trees, and Internet-like topologies that offer routing tables of sizes that scale logarithmically with the network size, we demonstrate in this paper that in view of recent results in compact routing research, such logarithmic scaling on Internet-like topologies is fundamentally impossible in the presence of topology dynamics or topology-independent (flat) addressing. We use analytic arguments to show that the number of routing control messages per topology change cannot scale better than linearly on Internet-like topologies. We also employ simulations to confirm that logarithmic routing table size scaling gets broken by topology-independent addressing, a cornerstone of popular locator-identifier split proposals aiming at improving routing scaling in the presence of network topology dynamics or host mobility. These pessimistic findings lead us to the conclusion that a fundamental re-examination of assumptions behind routing models and abstractions is needed in order to find a routing architecture that would be able to scale ``indefinitely.''Comment: This is a significantly revised, journal version of cs/050802

Automated Formal Analysis of Internet Routing Configurations

Today\u27s Internet interdomain routing protocol, the Border Gateway Protocol (BGP), is increasingly complicated and fragile due to policy misconfigurations by individual autonomous systems (ASes). To create provably correct networks, the past twenty years have witnessed, among many other efforts, advances in formal network modeling, system verification and testing, and point solutions for network management by formal reasoning. On the conceptual side, the formal models usually abstract away low-level details, specifying what are the correct functionalities but not how to achieve them. On the practical side, system verification of existing networked systems is generally hard, and system testing or simulation provide limited formal guarantees. This is known as a long standing challenge in network practice --- formal reasoning is decoupled from actual implementation. This thesis seeks to bridge formal reasoning and actual network implementation in the setting of the Border Gateway Protocol (BGP), by developing the Formally Verifiable Routing (FVR) toolkit that combines formal methods and programming language techniques. Starting from the formal model, FVR automates verification of routing models and the synthesis of faithful implementations that carries the correctness property. Conversely, starting from large real-world BGP systems with arbitrary policy configurations, automates the analysis of Internet routing configurations, and also includes a novel network reduction technique that scales up existing techniques for automated analysis. By developing the above formal theories and tools, this thesis aims to help network operators to create and manage BGP systems with correctness guarantee

The Scope of the IBGP Routing Anomaly Problem

Correctness problems in the iBGP routing, the de-facto standard to spread global routing information in Autonomous Systems, are a well-known issue. Configurations may route cost-suboptimal, inconsistent, or even behave non-convergent and -deterministic. However, even if a lot of studies have shown many exemplary problematic configurations, the exact scope of the problem is largely unknown: Up to now, it is not clear which problems may appear under which iBGP architectures. The exact scope of the iBGP correctness problem is of high theoretical and practical interest. Knowledge on the resistance of specific architecture schemes against certain anomaly classes and the reasons may help to improve other iBGP schemes. Knowledge on the specific problems of the different schemes helps to identify the right scheme for an AS and develop workarounds