Seamless network-wide IGP migrations

Abstract

Network-wide migrations of a running network, such as the replacement of a routing protocol or the modification of its configuration, can improve the performance, scalability, manageability, and security of the entire network. However, such migrations are an important source of concerns for network operators as the reconfiguration campaign can lead to long and service-affecting outages. In this paper, we propose a methodology which addresses the problem of seamlessly modifying the configuration of commonly used link-state Interior Gateway Protocols (IGP). We illustrate the benefits of our methodology by considering several migration scenarios, including the addition or the removal of routing hierarchy in an existing IGP and the replacement of one IGP with another. We prove that a strict operational ordering can guarantee that the migration will not create IP transit service outages. Although finding a safe ordering is NP-complete, we describe techniques which efficiently find such an ordering and evaluate them using both real-world and inferred ISP topologies. Finally, we describe the implementation of a provisioning system which automatically performs the migration by pushing the configurations on the routers in the appropriate order, while monitoring the entire migration process.

Safe, Efficient, and Robust SDN Updates by Combining Rule Replacements and Additions

“…We then generate a replacement constraint forcing any of the nodes in L init to be updated before any of the nodes in L f in . This has already been proved to prevent evil loops during the update [30]. Also, we generalize the intuition used in Fig.…”

“…Consider any potential evil loop L for flow f , as obtained by enumerating cycles in the graph G i f ∪ G t f . For replacement constraints, we adopt an approach similar to [30]:…”

Modeling complexity of enterprise routing design

“…There is a considerable amount of prior work on modeling individual routing protocols, particularly BGP [3,8,12,14], and also OSPF [21], to ensure correct, safe, and efficient behaviors from these protocols. There is also recent progress on safe migration of IGP protocols [25] and on modeling the interaction between multiple routing algorithms deployed in the same network [4]. In contrast, our work analyzes how specific routing protocols and primitives should be combined to meet a given set of design objectives, and the focus is on minimizing the complexity of the resulting design.…”

“…A top-down approach such as ours has several advantages. By working with design primitives directly (independent of router configuration files), the model is useful not only for analyzing an existing network, but also for "what if" analysis capable of optimizing the design of a new network and similarly, a network migration [25], or evaluating the potential impact of a change to network design. Further, our models help provide a conceptual framework to understand the underlying factors that contribute to configuration complexity.…”

Seamless transition of domain name system (DNS) authoritative servers

“…Gabner et al (2011) investigated service component migration between the mobile client and the infrastructure-based cloud as a means to avoid service failures and improve service performance. Vanbever et al (2011) proposed router grafting, where parts of a router are seamlessly removed from one router and merged into another, allowing a network operator to rehome a customer with no disruption. To improve the reliability and efficiency of a system in the pervasive computing domain, Cai et al (2013) proposed a service-oriented intelligent seamless migration (SOISM) mechanism and algorithm.…”