Peter Kline wrote

Another way of looking at this is that we know an ATM PVC over a DS3 using PLCP is configurable for a maximum of 96000 cells per second. 96000 cells per second * 48 payload octets per cell * 8 bits per octet = 36864000 bps, or 36.864 Mbps, not too far from what I observed above. With PLCP turned off, the maximum PVC config was ~105000 cells per second, yielding ~40.3 Mpbs.

The SAR function will add eight bytes to the payload. The eight bytes contain the CPCS-UU(1 bytes), CPI (1 byte), length of payload (two bytes) and a CRC (4 bytes). This additional overhead needs to be taken into account if you are segmenting small frames. The last cell after segmentation will have these eight bytes at the end of the cell plus any padding needed to fill out the cell. If you are segmenting a 96 byte payload for example you would think this would actually fit into two cells (using the 48 byte payload), but it really take three cells. The last cell would only contain padding and this overhead. Steve Murray Worldcom