In reply to a post by PaulKirby:

Saying that the splitter can split off 2 lots of 32, that meaning that instead of 4 strands entering the splitter there would be 8 strands.

The second "input" fibre is to give the splitter a second parent - a separate route, to a separate head-end - for resilience purposes. If one exchange goes off the air, the other one can take over responsibility. If someone digs up one E-side fibre, the other remains available.

That kind of "high availability" is usually more of a requirement for businesses, who would be looking for backup connectivity. It tends to cost a lot, so I'd expect to see it appear in high-end business locations.

In reply to a post by WWWombat:

In reply to a post by PaulKirby:

Saying that the splitter can split off 2 lots of 32, that meaning that instead of 4 strands entering the splitter there would be 8 strands.

The second "input" fibre is to give the splitter a second parent - a separate route, to a separate head-end - for resilience purposes. If one exchange goes off the air, the other one can take over responsibility. If someone digs up one E-side fibre, the other remains available.

That kind of "high availability" is usually more of a requirement for businesses, who would be looking for backup connectivity. It tends to cost a lot, so I'd expect to see it appear in high-end business locations.

Maybe, not really got another exchange close to me, but being FTTP that wouldn't be an issue.
But TBH I haven't really looked too much into the second lot of inputs of the splitter.

As for a requirement fro businesses, my area that is down as FTTP also supplies loads of shops i.e. businesses, so this "might" also be the case for my area.

Paul

I read a presentation from the researchers at BT, that dates back to 2010. Unfortunately, the one website with a copy seems to have gone offline.

It made a proposal for a fibre grid, where the fibre spines didn't just radiate out from each exchange. Additionally, they built across the "no-mans land" between exchanges, allowing for fibre runs between the two.

Continue this chain across a few exchanges, and you end up with a link from one fibre head end to another. Continue it everywhere, and you can create a fully-flexible grid of access network connection. Greatly improved resilience, by building a small percentage of new ductingand fibre in those "no mans land" sections.

Whether BT actually did this is anyone's guess. Even though the splitters have the ability to be dual-parented, it doesn't mean that any of them are,

In reply to a post by WWWombat:

I read a presentation from the researchers at BT, that dates back to 2010. Unfortunately, the one website with a copy seems to have gone offline.

It made a proposal for a fibre grid, where the fibre spines didn't just radiate out from each exchange. Additionally, they built across the "no-mans land" between exchanges, allowing for fibre runs between the two.

Continue this chain across a few exchanges, and you end up with a link from one fibre head end to another. Continue it everywhere, and you can create a fully-flexible grid of access network connection. Greatly improved resilience, by building a small percentage of new ductingand fibre in those "no mans land" sections.

Whether BT actually did this is anyone's guess. Even though the splitters have the ability to be dual-parented, it doesn't mean that any of them are,

That would require huge amounts of fibre, but you would get a more redundant connection and it would allow for passing off some bandwidth from areas that are not using it to areas that are requiring more.
Also it would still work if a cable it sliced in have by road works.

Paul

I think you will find that the resilience is not automatically available but can be connected to if there is a failure. The splitter can use 2 inputs so give two seperate paths to a customer ( 2 FTTP connections) but each connection is permanantly connected to that input.

The splitter is not an active switch but a permanant connected path from input to output.

The splitter works on wavelengths and each output is 1 wavelength on the input side.

In reply to a post by PaulKirby:

That would require huge amounts of fibre, but you would get a more redundant connection and it would allow for passing off some bandwidth from areas that are not using it to areas that are requiring more.

It wouldn't need "huge" amounts of cable, but certainly extra fibre, and it would need to be deployed differently, in 2 separate ways...

First, where (say) a 288 fibre cable runs out along one spine, it would need to remain as a count of 288 fibres all the way out to the far end. That means, when (say) 60 fibres are pulled off for one aggregation node - as the primary feed from the exchange - the spine would continue to carry 60 fibres out towards the exchange boundary - as the secondary feed that will come back in from the distant exchange.

Second, the gap between exchange areas (ie between the ends of the fibre spines) would need to be dug, ducted, and filled with the same fibre count cable.

The presentation did some analysis in 3 urban exchange areas, and reckoned that it would need 5-10% extra cable length, and cover 3-4 gaps in each exchange, giving added resilience to 70%+ of businesses. No word on how many fibres, though.

They might not need to make every splitter resilient, and instead deploy a few splitters that are deployed specifically for business use. In that case, the fibre count out the extreme end of the fibre spine could drop, with only a few fibres allocated for secondary routes.