Cell Switching

Cell Switching

ATM networks use cell switching rather than packet routing or frame broadcasting. This is an efficient compromise between telephone switching and packet routing.

A cell is a fixed length packet with 5 header bytes and 48 data bytes, laid out roughly as:

The identifier and fragment info allow higher level protocols to deal with fragmentation.

The CRC checks the header only; with low error rates, data is checked in s/w by the receiver, or possibly not at all for video/sound data.

path

identifier

CRC

data . . .

frag