Why ATM cells have a small and fixed size?

[Open Intelligence]

1. Allows better statistical multiplexing of information on a given medium than does the use of larger packets of variable length.

2. With longer variable-length packets, high-speed switching would be more complex.

3. The limited amount of information in the header allows ATM cells to be processed at a very high rate from 150 Mbps to several Gbps.

4. Provides speed, flexibility and compatibility with many different applications and physical media.

5. The reduced size of the internal buffers guarantees a minimal delay and delay jitter. This is why ATM can handle both constant rate traffic (audio, video) and variable rate traffic (data) easily.

6. To limit the queuing delays in internal buffers.