Slot reservations for lossless optical burst switching

The biggest disadvantage of optical burst switching lies in the high packet losses which are inevitable due to the lack of adequate optical buffering. Thus, the advantage of avoiding pay load translation into the electrical domain comes at the cost of dropping packets contending for the same output port whenever this contention persists for more packets than the limited fiber delay lines can accommodate. A method to avoid these losses is proposed in this paper by sending instead of a burst header a scout header over the control channel to simulate the events that the actual packet experiences. Once the scout message is informed in an intermediate node that a drop is inevitable, it comes back and prevents the sending of the actual packet, a new scout is issued instead. If all is okay, then the packet is launched with no loss certainty. To enable this, a slotted approach is adopted with all the necessary control tools. The penalty is the delay of the indirect reservations and the occasional repetitive attempts limiting the applicability of this approach to a couple of thousand kilometres