Periplus: A Resilient In-band SDN Control Plane via Embedded Forwarding Graphs

An in-band SDN control plane achieving sub-50 ms failure recovery, scalable bootstrapping, and constant per-switch flow-table footprint

E. M. Castro Barbero; P. de las Heras Quirós; F. J. Simó Reigadas· 2026· DOI 10.48550/arXiv.2607.14869

The core problem

Many resource-constrained, wide-area telecommunications deployments could benefit from an in-band SDN control plane, but several challenges stand in the way. This paper presents Periplus, an in-band SDN control plane designed to address four challenges that this approach presents in such contexts: automatic bootstrapping, source-based routing, fast failure recovery, and multi-controller coordination. The first three are developed in detail, while multi-controller coordination is addressed in a separate paper. For bootstrap, Periplus avoids network-wide flooding: when a new switch joins, the controller installs flow rules in only two switches. For routing and failure recovery, Periplus encodes a primary path and per-hop alternatives in a graph structure encapsulated between L2 and L3 headers; switches forward along the primary path and, upon detecting a failure, fall over locally to the encoded alternative without controller involvement. We evaluate a Ryu-based implementation of Periplus in Mininet across multiple topologies. Periplus runs on stock Open vSwitch (OVS), relying only on its built-in Nicira extensions for Network Service Header (NSH) encapsulation. The evaluation shows

The evaluation shows sub-50 ms failure recovery, scalable bootstrap across topologies of varying size and diameter, and a per-switch flow-table footprint that is independent of network size and grows only at switches where the controller encodes multiple alternatives. These results demonstrate that Periplus achieves fast local failure recovery without controller involvement, and that its bootstrapping mechanism scales without network-wide flooding. The flow-table footprint remains constant per switch regardless of network size, except at switches where multiple alternatives are encoded. The implementation runs on stock Open vSwitch (OVS) relying only on its built-in Nicira extensions for Network Service Header (NSH) encapsulation.

Many resource-constrained, wide-area telecommunications deployments could benefit from an in-band SDN control plane, but several challenges stand in the way. This paper presents Periplus, an in-band SDN control plane designed to address four challenges that this approach presents in such contexts: automatic bootstrapping, source-based routing, fast failure recovery, and multi-controller coordination. The first three are developed in detail, while multi-controller coordination is addressed in a separate paper. For bootstrap, Periplus avoids network-wide flooding: when a new switch joins, the controller installs flow rules in only two switches. For routing and failure recovery, Periplus encodes a primary path and per-hop alternatives in a graph structure encapsulated between L2 and L3 headers; switches forward along the primary path and, upon detecting a failure, fall over locally to the encoded alternative without controller involvement. We evaluate a Ryu-based implementation of Periplus in Mininet across multiple topologies. Periplus runs on stock Open vSwitch (OVS), relying only on its built-in Nicira extensions for Network Service Header (NSH) encapsulation. The evaluation shows sub-50 ms failure recovery, scalable bootstrap across topologies of varying size and diameter, and a per-switch flow-table footprint that is independent of network size and grows only at switches where the controller encodes multiple alternatives.

Periplus is implemented as a Ryu-based SDN controller and evaluated in Mininet across multiple topologies. The design leverages stock Open vSwitch (OVS) with built-in Nicira extensions for Network Service Header (NSH) encapsulation. The core mechanism embeds a forwarding graph between L2 and L3 headers. This graph encodes a primary path and per-hop alternatives. Switches forward packets along the primary path; upon detecting a failure, they locally fall over to the encoded alternative without controller involvement. For bootstrapping, the controller installs flow rules in only two switches when a new switch joins, avoiding network-wide flooding. The evaluation assesses failure recovery time, bootstrap scalability across topologies of varying size and diameter, and per-switch flow-table footprint. The flow-table footprint is independent of network size and grows only at switches where the controller encodes multiple alternatives. Multi-controller coordination is addressed in a separate paper and is not evaluated here.

Periplus addresses three of the four challenges of in-band SDN control planes in resource-constrained, wide-area telecommunications deployments: automatic bootstrapping, source-based routing, and fast failure recovery. The fourth, multi-controller coordination, is deferred to a separate paper. The key innovation is the embedding of a forwarding graph between L2 and L3 headers, which enables switches to make local failover decisions without controller involvement, achieving sub-50 ms recovery. The bootstrapping approach avoids network-wide flooding by installing flow rules in only two switches when a new switch joins, which contributes to scalability. The per-switch flow-table footprint is independent of network size, growing only where multiple alternatives are encoded. This design is compatible with stock Open vSwitch and leverages existing Nicira extensions for NSH encapsulation, facilitating deployment. The evaluation in Mininet across multiple topologies confirms the scalability and recovery performance. Future work includes multi-controller coordination, which is essential for larger deployments. Overall, Periplus offers a resilient and scalable in-band control plane suitable for resource-constrained environments.

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