ATM Cell Structure Explained Simply | Generated by AI
I’ll search for information about ATM cell structure to provide you with a comprehensive explanation.## Question:
What is the fixed cell length of ATM (Asynchronous Transfer Mode), and what is the composition of the cell structure?
Answer:
The correct answer is C: 53 bytes.
ATM Cell Structure Breakdown
An ATM cell consists of a fixed length of 53 bytes total, composed of a 5-byte header (containing cell header data) and a 48-byte payload (containing user information).
Detailed Composition
Header (5 bytes): The header contains critical routing and control information including:
- Virtual Path Identifier (VPI) and Virtual Channel Identifier (VCI) that identify the next destination of a cell as it transfers through ATM switches
- Payload Type (PT) indicating whether the cell contains user data or control data
- Cell Loss Priority (CLP) indicating whether the cell should be removed if extreme congestion is encountered
- Header Error Control (HEC) that evaluates checksum only on the first 4 bytes of the header
Payload (48 bytes): The 48 bytes of payload may optionally contain a 4-byte ATM adaptation layer and 44 bytes of actual data, or all 48 bytes may be data, based on a bit in the control field of the header.
Why 53 Bytes?
The 48-byte payload was chosen as a compromise between the United States proposal of 64-byte payloads (optimized for data transmission) and European proposals of 32-byte payloads (optimized for real-time voice applications). The 5-byte headers were chosen because it was thought that 10% of the payload was the maximum acceptable overhead for routing information.
Key Advantages
The fixed-cell size of 53 bytes enables rapid hardware switching and low jitter, which is essential for real-time applications, and allows for predictable delay and minimal queuing.
References:
- https://www.tutorialspoint.com/explain-the-atm-cell-structure-in-computer-network
- https://en.wikipedia.org/wiki/Asynchronous_Transfer_Mode
- https://www.sciencedirect.com/topics/computer-science/asynchronous-transfer-mode
- https://www.ou.edu/class/telecomm/lect08_atm_b.htm
- https://networkencyclopedia.com/cell-in-atm/