Tech specs on Chorus last mile equipment used

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MichaelNZ

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#3320775 15-Dec-2024 13:52

andynz:

But can anyone fill me in on if the fibre connection is single or multi mode, types of joins being done (I had assumed they would be fused but looking at installs the fibre is being cleaved, a push on connector attached and then push fit into the ONT or roadside splitter), fibre type etc.

As others have said its single mode. Pretty much always SM in telco. At the ISP I work for we use SM on fibre patch leads some as short as 1 metre.

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spacedog

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#3320829 15-Dec-2024 14:54

MichaelNZ:

andynz:

But can anyone fill me in on if the fibre connection is single or multi mode, types of joins being done (I had assumed they would be fused but looking at installs the fibre is being cleaved, a push on connector attached and then push fit into the ONT or roadside splitter), fibre type etc.

As others have said its single mode. Pretty much always SM in telco. At the ISP I work for we use SM on fibre patch leads some as short as 1 metre.

Single Mode and Single fibre are not necessarily the same thing, right? If I understand this correctly, in residential chorus installs there are actually two fibre strands, but only one gets used and TX and RX occurs on that single strand?

MichaelNZ

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#3320830 15-Dec-2024 15:01

spacedog:

Single Mode and Single fibre are not necessarily the same thing, right? If I understand this correctly, in residential chorus installs there are actually two fibre strands, but only one gets used and TX and RX occurs on that single strand?

Single mode refers to how the light travels through the fibre. To elaborate on what I said - Multi mode used to be more common for short distances because it was cheaper then single mode but the price difference has narrowed especially in the sub-100Gbps speed.

There are both single and dual fibre options. The dual modules are a lot cheaper and this is what we use inside DC's. These are commonly called "duplex" but thats actually a bit misleading. Both are duplex its just that the single fibre version achieves this by using different wavelengths. The single fibre modules are more expensive but are usual for WAN use to reduce costs by using half the number of strands.

Yes - all GPON networks are single strands. The standard Chorus feed in cable contains 2 of these so could be used for 2 ONT's.

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raytaylor

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#3323269 22-Dec-2024 15:17

To answer the question,
For a single dwelling unit, chorus will blow a 2F hexatronic stingray microfibre inside a 5/3.5mm microduct up to the ETP splice enclosure.

Then there are two options

1) From there it will be more 5/3.5mm microduct going into the house to the ITP splice enclosure.
Inside that enclosure a pigtail with an SC/APC connector is spliced on and that will connect to the ONT mounted to the front of the ITP splice enclosure, or it will go via a keystone jack on the bottom of the ITP with a ~15cm short patch lead to the ONT mounted to the front of the enclosure.

2) From there, one of the fibers will be spliced to a 2F Prysmian opticat cable (OptiC@t™5e) which runs to the ITP splice enclosure. The opticat cable also contains 4x copper pairs rated at least to the cat5e standard which are mostly used for bringing telephone back out to the old copper ETP for enabling the existing telephone reticulation to be backfed from the ONT.

The ONT communicates using bidirectional optics on one single fiber.

A legal requirement on chorus and the other local fibre companies requires them to install capacity for UFB unbundling.
This is a future service where internet providers may install their own OLT's in the telephone exchange and their own splitters inside roadside splicing cabinets/pits.
There is a spare fiber going to the house for this purpose - an entirely parallel dark network which is completely optically separated from the chorus lit network.

So if an ISP requires, they can have their own ONT inside the house with most of the cabling already installed from the initial chorus installation and the ISP's ONT can be installed next to the chorus ONT.

Alternatively if the customer orders a second ONT to be installed, there is a spare fiber to the ETP for that, and if the ONT is to be installed next to the existing ONT then there is a spare fiber already to the existing one which can be used for an easy installation.

ETP=External termination point / splice enclosure INH-8010221
ITP=Internal termination point / splice enclosure and ONT wall mounting bracket

Ray Taylor

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Wheelbarrow01

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#3323406 22-Dec-2024 22:52

Ray is correct - on 01 January 2020, Chorus, Enable, Northpower and TFF all became obliged to offer layer 1 fibre access (aka unbundled fibre) to any retailer who wants to take it up. I am not aware of any that have done so to date.

This is primarily what the second fibre in the 2F cable to each property is for, however it can also be used for an additional ONT service on a layer 2 offer when requested.

Definitions:

Layer 1: A latent fibre link between two points, provided by the LFC. The retailer then places their own equipment at each end and "lights" it with their own service and speed settings so that it can carry traffic. Essentially the LFC provides the glass in the ground, but nothing else.

Layer 2: The LFC provides the equipment to light the fibre, and the speed profile (eg 100/20Mbps) over which the traffic travels. Layer 2 includes a point of interconnect (aka a handover point) between the LFC's network and that of the retailer.

The views expressed by me are not necessarily those of my employer Chorus NZ Ltd

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