“全生命周期内是否存在具有全维可扩展性的理想网络”始终是网络体制或架构研究的第一性问题。迄今为止，所有单一网络体制都无法科学地践行理想网络的设计准则，难以在整个生命周期内做到既能适配应用场景清晰的预期业务又能支撑不断发展丰富的未来业务。研究证明，理论上任何单一网络体制都无法在服务质量承诺（S）、资源复用性（M）、业务多样性（V）三个维度上同时满足全生命周期内的可扩展性需求，存在“SMV不可能三角”困局，唯有变革当前网络发展范式，才能从思维视角、方法论和实践规范层面化解全维可扩展性与统一网络基础设施之间的矛盾。本文提出多模态网络环境（PNE）理论框架，其第一性原理就是将基础设施环境与应用网络体制分离或解耦，在给定资源条件下，基于网络基线的元素化、资源动态聚合及软硬件协同编排等核心技术生成“网络之网络”能力，从而在时空维度上用“生成式网络”形态建构为变化而设计、可共生共存的理想网络体制。原理验证环境测试表明，生成的多种有代表性的应用网络模态既能互不影响地共生共存，也能在技术经济指标约束下各自独立匹配定义清晰的多媒体业务或自定义服务。

The question of whether an ideal network exists with global scalability in its full life cycle has always been a first-principles problem in the research of network systems and architectures. Thus far, it has not been possible to scientifically practice the design criteria of an ideal network in a unimorphic network system, making it difficult to adapt to known services with clear application scenarios while supporting the ever-growing future services with unexpected characteristics. Here, we theoretically prove that no unimorphic network system can simultaneously meet the scalability requirement in a full cycle in three dimensions-the service-level agreement (S), multiplexity (M), and variousness (V)-which we name as the "impossible SMV triangle" dilemma. It is only by transforming the current network development paradigm that the contradiction between global scalability and a unified network infrastructure can be resolved from the perspectives of thinking, methodology, and practice norms. In this paper, we propose a theoretical framework called the polymorphic network environment (PNE), the first principle of which is to separate or decouple application network systems from the infrastructure environment and, under the given resource conditions, use core technologies such as the elementization of network baselines, the dynamic aggregation of resources, and collaborative software and hardware arrangements to generate the capability of the "network of networks." This makes it possible to construct an ideal network system that is designed for change and capable of symbiosis and coexistence with the generative network mor-pha in the spatiotemporal dimensions. An environment test for principle verification shows that the generated representative application network modalities can not only coexist without mutual influence but also independently match well-defined multimedia services or custom services under the constraints of technical and economic indicators.