AI 中文总结
研究带内SDN控制平面中多控制器协调问题，提出Periplus的多控制器协调平面，通过C-Adv消息发现邻居、构建路由，评估基于Ryu在Mininet中的实现，结果显示其可扩展性好、收敛快且无需修改交换机固件。
AI 中文摘要
带内软件定义网络（SDN）控制平面中，控制流量与数据平面基础设施共享，适用于如农村骨干网等广域、资源受限的部署。将此类网络跨多个控制器分区可提高可扩展性，但带来协调挑战。本文介绍了Periplus的多控制器协调平面，其单控制器设计在另一篇论文中提出。Periplus控制器通过控制器通告（C-Adv）消息发现邻居并逐步构建控制器间路由，每个边界交换机插入仅覆盖下一个域的部分转发图，且在控制器故障后，相同机制可将交换机重新连接到幸存控制器。我们在Mininet中评估了基于Ryu的实现，包括96个交换机、5个控制器的场景。结果表明，每个交换机的流表状态由其角色设置而非网络大小，随着控制器添加内部占用率保持不变，分区可扩展到约一百个交换机的网络，且控制器间发现可在数秒内收敛。该设计无需修改交换机固件，仅使用其内置的Nicira扩展进行网络服务头（NSH）封装。
英文摘要
In-band SDN control planes, where control traffic shares the data-plane infrastructure, suit wide-area, resource-constrained deployments -- such as rural backbones -- that cannot afford a dedicated control network. Partitioning such a network across multiple controllers improves scalability but raises a coordination challenge that in-band designs have largely ignored: controllers must discover one another and exchange state in-band, and switches must recover when their controller fails, all without forwarding state that grows with the number of controllers. This paper presents the multi-controller coordination plane of Periplus, an in-band control plane whose single-controller design is developed in a companion paper. Periplus controllers discover their neighbors through Controller Advertisement (C-Adv) messages and build inter-controller routes incrementally: each border switch inserts a partial forwarding graph covering only the next domain, so per-controller forwarding state is confined to border switches and never distributed across the interior of an intermediate domain. The same C-Adv mechanism reattaches a switch to a surviving controller after a controller failure. We evaluate a Ryu-based implementation in Mininet, including a 96-switch, 5-controller scenario. Per-switch flow-table state is set by a switch's role rather than by network size -- interior occupancy stays constant as controllers are added -- partitioning scales bootstrap to networks of around a hundred switches, and inter-controller discovery converges within seconds. The design needs no switch-firmware modifications: it runs on stock Open vSwitch, using only its built-in Nicira extensions for Network Service Header (NSH) encapsulation.
Comments22 pages, 10 figures, 2 algorithms
