A switch segments variable length frames into cells for transmission over
a cell-based switch fabric and handles rate differences between the input
data rate and the switch fabric data rate. The fabric handles multiple
cell packets by maintaining a switch path until a certain number of cells
are transmitted as indicated in a length field in the first data cell.
The first cell contains a full data payload, and a length field value
sufficient to handle a maximum length frame. Subsequent cells can contain
less than a full data payload, with the number of valid bytes in the cell
being indicated in the length field. The last cell used to segment the
frame contains an end of frame indicator. The indicator signals the
destination port side of the switch to terminate the packet path in the
switch fabric prematurely--before the number of cells indicated in the
first data cell.