Notes on the Physical Layer of Networking
Understanding the Physical Layer
- The physical layer is the foundational aspect of the network stack model, crucial for data transmission.
- Focus: Its primary aim is to move bits (ones and zeros) from one link to another.
Complexity of the Physical Layer
- Although it seems straightforward, the physical layer involves complex mathematical and engineering principles to transmit vast amounts of data efficiently and swiftly.
- Most underlying complexities are abstracted away for easier comprehension.
Key Components of the Physical Layer
- Bits: The smallest unit of data representation, either a one (1) or a zero (0).
- Data Transmission: Network data is comprised of frames and packets, which utilize these bits for full communication.
Real-World Applications
- Examples of activities using the physical layer include:
- Streaming music
- Sending emails
- Using ATMs
- All of these actions involve transmitting bits across various networks to reach a server.
Transmission Medium
- Copper Network Cable: Commonly used for physical layer communication.
- When linked to devices, it maintains a constant electrical charge for data transmission.
Modulation Techniques
- Modulation: Refers to varying the electrical voltage across network cables to transmit data.
- More specifically known as Line Coding in computer networks, it enables clear communication of bits.
- The specific state of voltage determines whether it represents a zero or a one.
Efficiency of Modern Networking
- With line coding, modern networks can transmit an astounding 10 billion bits per second through a single cable.
- This capability demonstrates the power and sophistication of the physical layer despite its simplicity in concept.
