But as Linux already incorporates a layer-2 switch within the kernel, some have asked why a virtual switch is even necessary.

但是，因为Linux已经在内核中包含一个2层交换机，所以有人可能会问，为什么会需要虚拟交换机？

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Layer 2: Enterprise components layer.

层2：企业组件层。

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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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Some have even gone as far as to state that Sony's strategy of using MPEG-2 and uncompressed PCM audio on single-layer Blu-ray discs may have required too much video compression, resulting in early releases that don't match the sharpness of VC-1 encoded movies available on HD DVD.

ENGADGET: Pre-release Blu-ray impressions roundup HD

Cocoon features a ported enclosure and a built-in, 2-way speaker system with dual-layer woofers for resounding low frequency response.

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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.

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