Data Link Protocols are a set of rules that govern data transmission at the Data Link Layer of the OSI model.
- These protocols ensure reliable, error-free communication between devices by managing how data frames are packaged, transmitted, and received.
Asynchronous Transmission
Asynchronous transmission is a method of data communication where information is sent one character (or byte) at a time, with each character framed by special start and stop bits to indicate the beginning and end of the data.
- This ensures that the sender and receiver remain synchronized without requiring a shared clock.
Features:
- Data is transmitted at irregular intervals.
- Start and stop bits provide synchronization for each byte.
- Simple and cost-effective, commonly used for low-speed data communication.
Advantages:
- No need for a shared clock between sender and receiver.
- Suitable for applications like keyboards, serial ports, and low-speed links.
Disadvantages:
- Less efficient due to added start and stop bits.
- Higher overhead for large amounts of data.
Synchronous Transmission
Synchronous transmission is a method of data communication where data is sent in a continuous stream, organized into frames or blocks, and synchronized using a shared clock signal or specific synchronization characters between the sender and receiver.
- Used in networks like Ethernet and Frame Relay.
Features:
- Frames or blocks of data are transmitted instead of individual bytes.
- Synchronization is maintained using a clock signal or special synchronization characters.
- Suitable for high-speed data transmission.
Advantages:
- Higher efficiency since no start/stop bits are required.
- Ideal for bulk data transfer and real-time applications.
Disadvantages:
- Requires clock synchronization.
- More complex and costly to implement.
Transmission Efficiency
Transmission efficiency refers to the ratio of actual data transmitted to the total data sent, including overhead like headers, trailers, and error correction bits.
- It measures how effectively a transmission system utilizes its bandwidth.
Asynchronous Transmission Efficiency:
- Lower due to start and stop bits added to each byte.
- Ideal for low-data-volume communication.
Synchronous Transmission Efficiency:
- Higher because data is sent in blocks without start and stop bits.
- Reduces overhead in high-volume data transfer.