Consider a 64 x 64 Crosspoint Switch, with 64 I/Os on the "A" side, and 64 I/Os on the "B" Side:
"A" Side 64 I/Os <---n mirrors---> "B" Side 64 I/Os
The mirrors serve to provide optical connectivity (through their reflective qualities) between laser outputs on the "A" side of a dwdm router or OADM (optical add drop mux), and photodetector inputs on the "B" side of the dwdm router or OADM. Of course, both the A and B sides have both Inputs and outputs, but we'll only consider one direction here at this time.
The mirrors serve to complete the "contacts" in crosspoint switching elements, only optically instead of through the use of fibers. If we were to look at this in its electrical model equivalent, then, through the use of metallic relay contacts in the electrical model.
It could become a bit more elaborate than how I just explained it, in the case of mirrors, with some possible combinations including:
laser output-->mirror-->mirror-->channel input (photodetector)
Since the mirrors are on swivels or hinges, they can point to any receiver on the other side of the element (whether its another mirror or a dwdm input) within its own lookup table range, under software control, or driven by traffic addresses during route decision and forwarding processes. It's this last part, for real time packet and flow forwarding, that I don't think mirrors are very well suited over the long term. |
