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Figure 6.13 MAC and LLC header of a WLAN frame.
If the frame contains user data, the Logical Link Control header (LLC header, layer 2)
follows the MAC header. The most important job of the LLC header is to identify which
protocol is used on layer 3.
6.6 The Physical Layer and MAC Extensions
On layer 1, the physical layer, also referred to as the PHY, there are different modulation
standards, as shown in Section 6.2, which are defined in the IEEE 802.11b, g, a, n and ac
standards.
