There is an interesting aspect of the room 641a story that could turn out to be different in detail: The Wikipedia article says, as do other accounts, that be

There is an interesting aspect of the room 641a story that could turn out to be different in detail: The Wikipedia article says, as do other accounts, that beam splitters were used to tap into fiber optic lines. That might in fact be how it was done, but I do not think that was necessary. IIRC, Juniper core routers were (uniquely, at the time?) capable of duplicating traffic on a NIC to another NIC without performance impact on capacity as a whole. This would have made them particularly suitable for mass surveillance that would not show up in network management metrics.