Software defined networking (SDN) gains a lot of interest from network operators due to its ability to offer flexibility, efficiency and fine-grained control over forwarding elements (FE) by decoupling control and data planes. In the control plane, a centralized node, denoted controller, receives requests from ingress switches and makes decisions on path forwarding. Unfortunately, requests processing may lead to controller performance degradation as the number of incoming requests goes up. This paper deals with the controller performance issue in Software Defined WAN (SD-WAN). Mainly, it proposes a new approach to optimize the switch-to-controller assignment problem with load balancing support. The issue is formulated as a Minimum Cost Bipartite Assignment optimization problem which is solved using an improvement of the Hungarian algorithm. The new algorithm is based on the introduction of the load-driven penalty concept which aims to achieve a trade-off between the round trip time and the controller load. Finally, a new protocol denoted Distributed Hungarian-based Assignment Protocol (DHAP) is described as an implementation of the proposed solution in multi-controller environments. As shown in results, the proposed solution outperforms parallel schemes in terms of flow setup time and load balancing.

中文翻译：

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在多控制器软件定义广域网 (SD-WAN) 中通过负载平衡改进交换机到控制器的分配

软件定义网络 (SDN) 能够通过分离控制平面和数据平面来提供对转发元素 (FE) 的灵活性、效率和细粒度控制，因此它引起了网络运营商的极大兴趣。在控制平面中，一个中心节点，称为控制器，接收来自入口交换机的请求，并对路径转发做出决定。不幸的是，随着传入请求数量的增加，请求处理可能会导致控制器性能下降。本文涉及软件定义广域网 (SD-WAN) 中的控制器性能问题。主要是提出了一种新的方法来优化具有负载平衡支持的交换机到控制器分配问题。该问题被表述为最小成本二部分配优化问题，该问题使用匈牙利算法的改进来解决。新算法基于负载驱动惩罚概念的引入，旨在实现往返时间和控制器负载之间的权衡。最后，一种称为分布式匈牙利语分配协议 (DHAP) 的新协议被描述为所提议解决方案在多控制器环境中的实现。如结果所示，所提出的解决方案在流设置时间和负载平衡方面优于并行方案。