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.

Abstractions for network update

“…The recent work by Vanbever et. al [5] also handles more significant intradomain routing changes, such as switching to a different routing protocol. Unlike our approach, these methods can only preserve basic properties such as loop-freedom and connectivity.…”

“…To address these problems, researchers have proposed a number of extensions to protocols and operational practices that aim to prevent transient anomalies [8,2,9,3,5]. However, each of these solutions is limited to a specific protocol (e.g., OSPF and BGP) and a specific set of properties (e.g., freedom from loops and blackholes) and increases the complexity of the system considerably.…”

Achieving Memory-saving Network Update

“…In the "Frenetic" project proposed in [10], two-phase update mechanisms are used to preserve consistency when performing network updates.…”

Abstractions for network update

“…However, despite the conceptual appeal of centralized control, No loops/blackholes Packet/bandwidth loss Traffic engineering [1,3] Changing a link weight No loops/blackholes Packet/bandwidth loss VM migration [4] Move server to new location No loops/blackholes Packet/bandwidth loss IGP migration [5] Adding route summarization No loops/blackholes Packet/bandwidth loss Traffic monitoring…”