[time-nuts] Re: NTP via Passive Optical Network (PON)

[Keelan Lightfoot]

I used to to a lot of work around analyzing and characterizing internet
latency, so I might be marginally qualified to answer this!

I imagine that the GPON induced jitter would be no worse than the queueing
induced jitter from the countless layer 2 and layer 3 hops that NTP packets
experience on their journey. A 2.5 Gbps GPON frame is 125 µs long,  which
is well below the noise floor of the of the rest of the internet,
especially if there are congested links in the path.

This page is interesting reading:
https://sites.google.com/site/amitsciscozone/gpon/gpon-fundamentals

- Keelan

On Thu, Jul 24, 2025 at 12:03 PM Kapp, Francois B. via time-nuts <
time-nuts at lists.febo.com> wrote:

> I was wondering if anyone has measured, or has seen results of
> measurements of the effect of a passive optical network on time transfer
> over NTP (or PTP). Intuitively, the fact that return communications are
> time division multiplexed should insert some jitter in the round trip time
> - any pointers to more concrete information?
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