Infrastructure as a Service (IaaS) in cloud environments provides compute, storage, networking, and other fundamental resources that allow consumers to deploy and run arbitrary software, including operating systems and applications. To support multi-tenant environments, IaaS leverages virtualization, but conventional overlay network architectures have become a direct cause of scalability limitations. In particular, current IaaS virtual networks face challenges in high availability and load balancing. To address these issues, we present EYWA, a virtual network architecture that scales to support very large data centers with high availability, efficient load balancing, and large layer-2 semantics. EYWA overcomes scalability limitations by: (1) accommodating a large number of tenants (about 2^24 = 16,777,216) through logically isolated virtual LANs with unique IP ranges, (2) providing per-tenant public network services without throughput bottlenecks or single points of failure in network address translation (SNAT/DNAT), and (3) enabling a single large IP subnet per tenant with extended layer-2 semantics. EYWA combines existing techniques into a distributed scale-out control and data plane. Its only component is an agent running on each hypervisor host, which collectively act as a distributed controller. As a result, EYWA can be deployed in today's multi-tenant cloud environments. We have implemented a proof-of-concept (PoC) of EYWA and evaluated its effectiveness through measurements and experiments in our lab.

翻译：基础设施即服务（IaaS）在云计算环境中提供计算、存储、网络以及其他基础资源，使消费者能够部署和运行任意软件，包括操作系统和应用程序。为支持多租户环境，IaaS采用了虚拟化技术，但传统覆盖网络架构已成为可扩展性限制的直接原因。特别是，当前IaaS虚拟网络在高可用性和负载均衡方面面临挑战。为解决这些问题，我们提出EYWA——一种可扩展至支持超大规模数据中心、具备高可用性、高效负载均衡和大二层语义的虚拟网络架构。EYWA通过以下方式克服可扩展性限制：（1）通过逻辑隔离的虚拟局域网及唯一IP范围容纳大量租户（约2^24 = 16,777,216个）；（2）为每个租户提供公共网络服务，避免网络地址转换（SNAT/DNAT）中的吞吐量瓶颈或单点故障；（3）为每个租户启用具有扩展二层语义的单一大型IP子网。EYWA将现有技术整合到分布式横向扩展的控制平面和数据平面中，其唯一组件是运行在每个虚拟机管理程序主机上的代理，这些代理共同充当分布式控制器。因此，EYWA可部署于当今的多租户云环境中。我们已实现EYWA的概念验证（PoC），并通过实验室的测量和实验评估了其有效性。