SDNA: 10GbE Software Defined Network Adapter


SDNA is a a software defined network adapter that transmits packets by modulating 1/10GbE bitstreams onto single mode optical fiber by means of a laser and a pulse pattern generator. Conversely SDNA receives packets by sampling the signal with an optical oscilloscope. By relying on the precisely calibrated time-base of the optical instruments we achieve six orders of magnitude improvement in packet timing precision over endpoint measurement and three orders of magnitude relative to prior hardware-assisted solutions. With SDNA we are able to demonstrate an interesting phenomenon: as it traverses an uncongested network, an input flow with packets homogeneously distributed in time (i.e. packets spaced by precisely the same number of idle symbols) becomes increasingly perturbed to such an extent that, within a few hops, the egress flow has become a series of minimally-spaced packet chains. Interestingly, this phenomenon occurs irrespective of the input flow data rate, and may cause packet loss.

Figure 1: SDNA hardware and software stack.




SDNA software stack (the black components in Figure 1), except for the “Clock Recovery” module

For the rest the components of the SDNA software stack, see also BiFocals