Physical layer protocols

The physical layer (Layer 1) represents both the physical and logical aspects of the computer network. Among the physical components are the network interface card (NIC), the medium for data transmission, and the network equipment. Among the logical components are electrical signals and the transmission time. In addition, standards such as network medium types, speeds, and distances are integral parts of the physical layer. The terms electrical signals and radio frequencies, often known as bits, are used to represent the Protocol Data Unit (PDU) at this layer, as shown in Figure 2.11. In this layer, the following communication protocols operate:

• IEEE 802.3
• IEEE 802.5
• IEEE 802.11