Traffic engineering is an important concept that allows Internet Service Providers (ISPs) to utilize their existing routing hardware more efficiently. One technology that can be used is Segment Routing (SR). In this paper, we address the use of SR to increase the resilience against failure scenarios. In addition, we develop solutions that are manageable and, thus, deployable in a tier 1 ISP network. We propose a post-convergence aware SR based optimization model. With it, we can proactively find a single SR configuration that is beneficial in all predefined failure scenarios, including single link failures, shared risk link group failures, and node failures. In addition to this usecase, we also extend the optimization model to include other important practical requirements such as keeping the number of SR tunnels to a minimum, avoiding arbitrary traffic splitting, or meeting latency bounds. We evaluate our approaches with recently measured data from a tier 1 ISP and show that we can improve over state of the art routing approaches.
Especially for large Network Operators (NOs), eliminating routing anomalies is an important aspect for the internal BGP design. To avoid such unwanted effects, classical architectures [1], [2], [3] have need of certain restrictions kept in both, the network design and the iBGP peering. However, these restrictions are in conflict with the optimized network designs NOs seek.In this study we develop an inherently anomaly-free iBGP architecture that takes the demands of NOs into account. It is based on a central server that guarantees consistent local views in the entire system. This is done by exchanging additional routing information with the Border Routers of the Autonomous System. The architecture implements the results of iBGP analyses made in [4]. Despite not being that as flexible as classical information reduction techniques, our design scales equal or better in practice. All required protocol extensions are supported by IETF Internet Drafts from persons affiliated with important router vendors.
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