Because RPR is a layer 2 MAC-based technology, it can operate over multiple physical layers, including SONET.

由于RPR是第二层基于MAC的技术，所以它能在多个物理层上工作，包括SONET。

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In this chapter we will study the design principles for layer 2, the data link layer.

在这一章中，我们将研究网络第二层——数据链路层的设计原则。

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The layer 3 switch technology which fits for the need of aggregation layer is a combination of the layer 2 switch technologies and routing.

三层交换技术将传统的二层转发和路由技术结合起来，特别适合汇聚层的需要。

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Gnodal acts as what is called a switch fabric, essentially an aggregator of other Layer 2 switches in the network.

FORBES: Why the Cloud Needs a Network Decongestant

Each node has 2-8 Xeon 5650 processors providing 6-48 coes and up to 768 GB of RAM, 1.3 TB of Fusion-io ioDrive PCIe flash cards and a mid-layer of up to 1.2 TB of Intel SSD storage.

FORBES: Explosive Growth in Flash Memory Enterprise Applications

To get beyond Eggleston's Freudian couch, swine also need a 2-inch-thick layer of exterior fat along the belly and back.

WSJ: High on the Hog