Within the measurement infrastructure, counters are structured using a two-level hierarchy.
在测量基础架构中，用两级层次对计数器进行结构化。
The Internet is a three level hierarchy composed of backbone networks, mid-level networks, and stub networks.
因特网由三个层次组成：骨干网，中间层次网和子网络。
The Internet is a three level hierarchy composed of backbone networks, mid-level networks, and stub networks.
因特网由三个层次组成：骨干网，中间层次网和子网络。
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