What is character count framing method in computer networks?

The character count framing method in computer networks is a technique where a field in the frame's header specifies the number of characters within that frame.

Here's a more detailed breakdown:

• Basic Functionality: The sender places a character count field at the beginning of the frame. This field indicates the total number of characters or bytes present in the frame, including the header, data, and any control characters (but typically excluding the count field itself).

• How it Works:

  1. The sender calculates the total number of characters to be included in the frame.
  2. This number is inserted into the character count field in the frame's header.
  3. The frame, including the character count, is transmitted.
  4. The receiver reads the character count field.
  5. The receiver then reads the specified number of characters from the incoming data stream. This allows the receiver to identify the end of the current frame and the beginning of the next frame.

• Example: Suppose the character count field contains the value '10'. This indicates that there are 10 characters following the character count field. The receiver reads these 10 characters as the complete frame and then knows the next character received starts the next frame (or inter-frame gap).

• Advantages:

  • Simple to implement.

• Disadvantages:

  • Error Sensitivity: This method is very vulnerable to errors. If the character count is corrupted during transmission, the receiver will misinterpret the frame boundaries, leading to synchronization problems and frame errors. Even a single bit error in the count field can cause the receiver to lose track of the frame boundaries.
  • Difficulty in Handling Variable-Length Frames Robustly: While it can handle them, the risk of misinterpretation due to errors is significant.

• Why It's Less Common Now: Due to its error-prone nature, character count framing is rarely used in modern high-speed networks. More robust methods like flag bytes with byte stuffing, or bit stuffing are preferred.

In summary, character count framing is a basic framing method that uses a character count field to delineate frames, but it is susceptible to errors, making it less practical for reliable data transmission in contemporary networks.