Software-Defined Networking (SDN) offers a new way to operate, manage, and deploy communication networks and to overcome many long-standing problems of legacy networking. However, widespread SDN adoption has not occurred yet due to the lack of a viable incremental deployment path and the relatively immature present state of SDN-capable devices on the market. While continuously evolving software switches may alleviate the operational issues of commercial hardware-based SDN offerings, namely lagging standards-compliance, performance regressions, and poor scaling, they fail to match the cost-efficiency and port density. In this paper, we propose HARMLESS, a new SDN switch design that seamlessly adds SDN capability to legacy network gear, by emulating the OpenFlow switch OS in a separate software switch component. This way, HARMLESS enables a quick and easy leap into SDN, combining the rapid innovation and upgrade cycles of software switches with the port density and cost-efficiency of hardware-based appliances into a fully dataplane-transparent and vendor-neutral solution. HARMLESS incurs an order of magnitude smaller initial expenditure for an SDN deployment than existing turnkey vendor SDN solutions while, at the same time, yields matching, or even better, data plane performance for smaller enterprises.

中文翻译：

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向SDN过渡是无害的：用于将旧式以太网交换机迁移到SDN的混合体系结构

软件定义网络（SDN）提供了一种操作，管理和部署通信网络并克服传统网络中许多长期存在的问题的新方法。但是，由于缺乏可行的增量部署路径以及市场上具有SDN功能的设备的相对不成熟的现状，尚未广泛采用SDN。尽管软件交换机的不断发展可以缓解基于商用硬件的SDN产品的操作问题，即标准合规性落后，性能下降和扩展性差等问题，但它们无法满足成本效益和端口密度的要求。在本文中，我们提出了HARMLESS，这是一种新的SDN交换机设计，它通过在单独的软件交换机组件中模拟OpenFlow交换机OS，将SDN功能无缝地添加到旧式网络设备中。这条路，HARMLESS使软件交换机的快速创新和升级周期与基于硬件的设备的端口密度和成本效益相结合，从而成为一种快速，轻松地过渡到SDN的完全数据平面透明且与供应商无关的解决方案。与现有的交钥匙式供应商SDN解决方案相比，HARMLESS的SDN部署所需的初始支出要少一个数量级，而与此同时，小型企业的数据平面性能却可以匹配甚至更好。