Optical devices are optoelectronic components used in optical communication that perform various functions based on the photoelectric conversion effect. Depending on whether photoelectric conversion occurs during operation, optical devices can be divided into active devices and passive. Optoelectronics (or optronics) is the study and application of electronic devices and systems that find, detect and control light, usually considered a sub-field of photonics.
[pdf] In this layer, the layer 2 switches are installed to distribute the data packets to the addressed group of access devices. When planning an enterprise access network, one of the most common dilemmas is whether to deploy Layer 2 (L2) or Layer 3 (L3) switches. The access layer plays a critical role in connecting end devices—such as computers, printers, IP phones, and wireless access points—to the rest of the enterprise. A Layer-2 switch works at the Data Link layer or Layer 2 of the OSI reference model.
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