Inter-Domain Routing

Routing across domains requires the exchange of reachability information across autonomous systems. Today, the Border Gateway Protocol (BGP) has become the de facto standard in productive systems operated by the Internet Service Providers. However, iBGP, the operational mode of distributing reachability information within a specific autonomous system, turned out to be susceptible to various anomalies and easy to manipulate in the way it is implemented today.

The effects can be observed in real life: In large autonomous systems, anomalies occasionally arise as nondeterministic or diverging subsystems. In some cases, incorrect configurations of individual systems resulted in nonreachability of You Tube or other “politically interesting” destinations from extensive parts of the Internet.

A complete re-design of a “robust Border Gateway Protocol” seems unfeasible due to the wide application of conventional BGP and due to the application across Internet Service Providers. Instead, the work group Communication Systems focuses on a step-by-step hardening of BGP which only relies on local architectures. This makes the techniques both future-proof and applicable in real systems on a long-term basis.

The basic idea of our approach to consistent routing across domains is a formal analysis of protocol functionality which provides a deep understanding of fundamental deficiencies of the protocol used today. As an example: The work group Communication Systems could show that oscillations are caused by information reduction techniques only. Studies performed in close co-operation with the German Telekom clarified that routing anomalies can completely be avoided by a suitable local architecture. However, excluding anomalies is only a first step in the direction of a robust, consistent and correct routing: The fast and reliable detection of manipulations is a goal equally important which has high relevance in real life. Based on the know-how obtained and as a continuation of related activities in this field, we are working on significant results and approaches for mastering theses challenges.


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