Evaluating the effect of centralization on routing convergence on a hybrid BGP-SDN emulation framework

Abstract

Xenofontas Dimitropoulos FORTH Heraklion, Greece fontas@ics.forth.gr MOTIVATIONA lot of applications depend on reliable and stable Internet connectivity. These characteristics are crucial for missioncritical services such as telemedical applications. An important factor that can affect connection availability is the convergence time of BGP, the de-facto inter-domain routing (IDR) protocol in the Internet. After a routing change, it may take several minutes until the network converges and BGP routing becomes stable again [13]. Kotronis et al. [8,9] propose a novel Internet routing approach based on SDN principles that combines several Autonomous Systems (AS) into groups, called clusters, and introduces a logically centralized routing decision process for the cluster participants. One of the goals of this concept is to stabilize the IDR system and bring down its convergence time. However, testing whether such approaches can improve on BGP problems requires hybrid SDN and BGP experimentation tools that can emulate multiple ASes. Presently, there is a lack of an easy to use public tool for this purpose. This work fills this gap by building a suitable emulation framework and evaluating the effect that a proof-of-concept IDR controller has on IDR convergence time. Categories and Subject Descriptors OBJECTIVESOur primary objective is to support hybrid BGP-SDN experiments with multiple ASes using real router software. This is needed since when deploying a new IDR approach one cannot change the whole infrastructure at once. The framework should take care of configuration management such as IP prefixes and BGP policy templates and the user . should be able to actively control the experiments, e.g., dynamically changing the topology and verifying the effects of changes. Furthermore, it should be possible to easily create topologies based on measured Internet data or theoretical models. This way an experimenter should be able to concentrate more on the experiments and her concept rather than bothering with configuration and management.Our second objective is to demonstrate the effect of centralization on IDR convergence time. We designed and implemented a proof-of-concept IDR SDN controller that exploits centralization to improve IDR convergence time based on the following design goals. First, the controller should inter-operate with legacy BGP routers. Moreover, the cluster network is transparent to the legacy BGP world, therefore ASes within the cluster maintain their AS identity. In addition, we want to support disjoint AS sub-clusters controlled by the same controller, so that an intra-cluster link failure does not isolate the controlled ASes: paths over the legacy Internet could still connect the sub-clusters. HYBRID SDN & BGP EMULATION FRAMEWORKThe framework is based on a slightly modified version of Mininet [10] that supports the functionality of Quagga [3] -a popular BGP software. The topologies can be either artificial or built from the iPlane Inter-PoP links [12] and the CAIDA AS Relationship [11] datasets. The ...

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