[AusNOG] Simon Hackett's presentation from Comms Day yesterday - NBN fibre on copper prices

[Matt Whitlock]

> > What happens if someone directs a laser pointer (at approximately the correct wavelength) down a GPON fibre interface?
My understanding is that all users on the same splitter could lose connectivity until the interference is removed (31 users + 1 one broadcasting the interference), depending on the wavelength broadcast and/or the optical power level.

> > What stops people from using WDM equipment or simply an optical transceiver at a different wavelength to "steal" wavelengths that the splitter can distribute between people on the same splitter?
NBN is not WDM-PON (AFAIK) and therefore there's no WDM equipment per se. A different frequency is used for transmit and receive because the connections are single-core (as opposed to dual-core). However, GPON is architected such that all receive traffic from the OLT is broadcast to all ONTs (NBN NTU in your house) on the splitter and the ones not expecting it discard it. The transmit from the ONTs back to the OLT is controlled by time slots, rather than frequency.

One thing that I believe happens is that when an ONT is added (either through new install or replacement of a faulty ONT) the OLT takes a couple of seconds to reset all of the relevant time slots. This will interrupt all traffic on the splitter until the process is completed. 

Ta,

Matt.