In the OSI model the physical layer play’s a critical roll in transporting the bits that make up the data link layer frame. The encoded bits that make up the frame are transmitted through the media and are received either on end devices or intermediate devices.
The physical layer encodes the frames and creates the electrical, optical. or radio wave signals that represent the bits in each frame.
Physical Layer Media
The physical layer has three basic forms of network media.
- Copper cable: Uses electrical pulses
- Fiber-optic cable: Uses patterns of light
- Wireless: Uses patterns of microwave
The Physical Layer of The OSI Model Standards
The physical layer standards are implemented in hardware and are governed by many organizations.
- International Organization for Standardization (ISO)
- Telecommunications Industry Association/Electronic Industries Association (TIA/EIA)
- International Telecommunication Union (ITU)
- American National Standards Institute (ANSI)
- Institute of Electrical and Electronics Engineers (IEEE)
Physical Layer Functional Areas
The physical layer has three functional areas:
- Physical Components: Electronic hardware devices, media, and connectors that transmit signals in bits. Other components include NICs, interfaces and cables.
- Encoding: Line encoding is a method of converting a stream of data bits into predefined code.
- Signaling: The physical layer generated the electrical, optical, or wireless signals that represent “1” and “0”.
The Physical Layer of a Network *Terminology*
- Wireless: Media that uses patters of microwaves to represent bits.
- Bandwidth: The capacity of a medium to carry data.
- Fiber-optic: Media that uses patters of light to represent bits.
- Throughput: A measure of the transfer of bits across the media.
- Copper: Media that uses electrical pulses to represents bits.