Abstract: A hierarchical queueing based optical buffer (HQOB) is presented for all opticalpacket switches. HQOB is in a layered structure. Each layer is a fiber loop buffer group, whose fiber length is multiple of the previous layer. As packets arenormally stored in queues, the middle part of a queue can be moved between adjacent layers when needed. Thus HQOB can simulate normal packet buffer with QoS support using much less FDL(fiber delay line) segments(proportional to the logarithm of the buffer depth). The amount of FDLs can be further reduced when WDM(wavelength division multiplexing) is employed.

Key words: all optical buffer, hierarchical queueing, fiber loopbuffer