In networking, the communications protocol that contains the physical address of a client or server station. It is called the "data link layer" or "MAC layer" and contains the address inspected by a bridge or switch. Layer 2 processing is faster than layer 3 processing, because less analysis of the packet is required. See MAC layer and OSI model.
The attraction to vendors of Layer 4 switching is irresistible: the Layer 2 (LAN) switch market exploded because these switches inexpensively micro-segmented LANs, thus providing vast performance improvements at a fraction of the cost of routers.
3M also discovered that if the refractive index in the horizontal or y direction for layer 1 equals the refractive index in the vertical or z direction for layer 2 (and vice versa), the film shows constant reflectivity from all viewing angles.