In reply to a post by kitcat:

bowden

You can serve 2 ports on an ONT from 1 CBT port. This is what the multiport ONTs are for.

One ONT with up to 4 ports, one Fibre back to the CBT, uses 4 streams back across the PON so PON capacity may be impacted but spread across all the capacity on the PON.

Only restriction I know of is each ONT can only have the TV streams on port 1. But if the others are for business use this doesn't matter.

Ahh, ok. I didn't know they could use both use 1 CBT. That makes sense.

Thank you for the information.

Openreach dimension a PON area on the basis of one ‘connection’ per SDU , so one CBT port per address, although the size of the CBT may seem to be be larger than necessary , for example one designed with a demand of 4 addresses wouldn’t use a 4 port , it would be an 8 port , but only 4 fibres are pushed through from the splitter , so 4 of 8 ports are ‘dark’ anyway
Although it’s extremely unlikely that OR would ever have 100% take up , theoretically if someone gets two separate physical connections, so two CBT ports, two ONTs , then potentially someone else could be denied ( even if it were only temporary ) as no port on the CBT would be ‘spare’.

This topic has been discussed a few times , there is no consensus, some state two separate connections will be employed, others state it will be a multi port ONT .
The obvious advantages of changing to a multi port where one connection already exists to a single dwelling , you don’t needlessly block a CBT port , with overhead work you don’t need to climb the pole again ( and climbing poles is avoided where possible) with underground you don’t have the possibility that the duct may no longer be serviceable, the consumer doesn’t need a second ONT , just swapping to a multi port , so no extra power outlets , there probably will be less power consumption, a single multiple port ONT is likely to be less power hungry than two separate ONTs .

The downstream optical path is identical on all 32 legs of a splitter, so using 2 of them into 1 address is unnecessary duplication, in that the ‘data’ on all splitter legs hits all ONTs on the splitter simultaneously, so having 2 separate ONT rather than effectively multiple ONT in one physical enclosure serves no purpose optically

Edited by Iniltous (Mon 06-Feb-23 10:27:30)

Hey everyone, Thought i'd update the thread and say the second ONT was installed early yesterday morning with zero issues and a fast service from zen.

Good to hear, and always nice to get a positive ending!