Thanks for explaining - that's good to know!
Welcome! On cable and RFoG networks before you can transmit you have to ask for permission and are given a set time period to send your data. That takes at least 2-4 ms depending on the timings set by the cable company. The time periods are in a message called the upstream MAP, and that's sent on the downstream to all devices in the segment at a set interval. The more often it's sent the more bandwidth the cable company loses to the overheads, but with the potential to provide lower baseline latency and jitter.
Also this comes with a loss of upstream bandwidth as there are 'contended minislots' in each message - these are where a modem sends its upstream burst to ask for slots to send data.
This all used to be a problem, actually, as the intervals limited the amount of times a modem could transmit but this was fixed through a combination of allowing modems to attach a request for more data to the last transmission they send, and through allowing modems to group a bundle of data into a single burst, filling empty spaces in the grant with small packets rather than one stream, one request, one burst.
https://people.computing.clemson.edu/~westall/851/do... is out of date now but still holds as far as BQM goes on RFoG - you have no DoCSIS 3.1 channel so it's basically the same as that PDF but on steroids.
Same story on PON networks actually however they both pre-emptively provide some bandwidth to each ONU and the request-grant-transmit cycle for more takes far less time.
----------
Exceptionalism diminishes, cooperation enhances.
Edited by XGS_Is_On (Thu 18-May-23 12:01:36)