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Standard User PaulKirby
(experienced) Fri 26-Jun-15 13:57:38
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Speed of a fibre strand?


[link to this post]
 
Hello All

Just wondering what the actual speed of an individual strand of fibre was.

This is for our FTTP install, where we are now just waiting for a fibre joiner to join our other end to where the faulty cable connected.

Basically BTOR has just put in a thin fibre cable (at a glance it seems the thickness of RG213 Coax) with about 96 or so strands instead of the 40 odd due to not having any, so I am aware depending on what that connects to would determine how many it will use leaving the rest for spare in case of issues.

But say that it only uses like 48 strands for all the homes on our phone cabinet which is about 394 (including phone boxes, bank tills and TFL) so say 350, that means 8 homes could/will be sharing the same strand, I did read some place that a fibre stand can handle several Gbits to Tbits or more depending where you read, so I was wondering what the average max speed would be per strand.

Thanks

Paul
Administrator MrSaffron
(staff) Fri 26-Jun-15 14:02:30
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Re: Speed of a fibre strand?


[re: PaulKirby] [link to this post]
 
All depends on what electronics you use to light the strand

A single strand can carry 1.4Tbps if you use DWM and the latest kit

In day to day world usually 1 Gbps or 10 Gbps.

If talking Openreach GPON then you are looking at GPON standard (which without checking I believe has 2.5 Gbps to share between users on the strand, that is then passively split, between 32 or 64 users or 128 users.

So probably use just 5 to 8 strands to serve your area, exact figure depends on the geographic layout.

The author of the above post is a thinkbroadband staff member. It may not constitute an official statement on behalf of thinkbroadband.
Standard User PaulKirby
(experienced) Fri 26-Jun-15 14:19:48
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Re: Speed of a fibre strand?


[re: MrSaffron] [link to this post]
 
Well I know they said we have 40 odd stands for our area (i.e phone lines on our cabinet) which due to not having that cable they used a 90 odd strand one.

But if say we go by what you said, in the worst cases if everyone hammers their connection we could see speeds as slow as 56Mbits or so from our soon 330Mbit connection.

I was in the thinking it would be a few strands per pole resulting in about 8 lines per strand.

Lets hope not everyone orders fibre LOL.

Anyhow I guess I will find out when it goes live, TBH anything would be better than what we are on now tongue

Paul


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Standard User TheEulerID
(member) Fri 26-Jun-15 14:38:47
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Re: Speed of a fibre strand?


[re: MrSaffron] [link to this post]
 
I believe 10gbps XG_PON has already been trialled in Cornwall, and I'm sure it won't stop there.

As far as back haul from future g.fast nodes is concerned, I saw an online OR presentation that was talking of many WDM channels down the same fibre giving the potential for several 10s, if not a 100 or more Gbps.

For all the talk of gigabit broadband, they will all have over-subscription somewhere in the connection back to the peering points. The secret is to have a enough users over a fat enough pipe that the load evens out. I seem to recall some of the early contended ADSL services were horrendous like that as just a couple of maxed-out users would wreck the performance for everybody on a contended backhaul link.
Administrator MrSaffron
(staff) Fri 26-Jun-15 14:42:42
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Re: Speed of a fibre strand?


[re: PaulKirby] [link to this post]
 
In Japan someone is selling 2 Gbps across standard GPON.

The author of the above post is a thinkbroadband staff member. It may not constitute an official statement on behalf of thinkbroadband.
Standard User PaulKirby
(experienced) Fri 26-Jun-15 14:46:27
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Re: Speed of a fibre strand?


[re: TheEulerID] [link to this post]
 
Well I just come across this page, granted its probably not correct.
https://en.wikipedia.org/wiki/Fiber-optic_communicat...

And I read that some company has a fibre cable that is 99.97% the speed of light and can support way higher than 10s of Gbits.
http://rt.com/news/200151-internet-speed-fiberoptic-...

But I guess BT are assuming that not everyone will want fibre and if they do they may only require the lower speeds.

Like I said, I won't really know until its live.

Paul
Standard User PaulKirby
(experienced) Fri 26-Jun-15 14:48:21
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Re: Speed of a fibre strand?


[re: MrSaffron] [link to this post]
 
In reply to a post by MrSaffron:
In Japan someone is selling 2 Gbps across standard GPON.
Ooooh Nice smile

Paul
Administrator MrSaffron
(staff) Fri 26-Jun-15 14:56:19
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Re: Speed of a fibre strand?


[re: PaulKirby] [link to this post]
 
The reality is that broadband NO MATTER HOW ITS DELIVERED is contended in the consumer area, that is why its a lot lower cost per month than a leased line.

Take-up of 200 Mbps and 300 Mbps Infinity 3 and 4 where available is pretty low, I can find speed tests as I know which areas have it available, but the majority still buy Infinity 1 and 2. Hyperoptic are not faster in the speed tables because they have users buying their 20 and 50 Mbps tiers and similar with Virgin Media.

Until 90% of homes own a UHD TV and buy UHD content then 20 to 30 Mbps is more than the majority of homes need to cope when everyone is at home.

The UHD market for video may push things towards the 100 Mbps being a more popular choice, i.e. run 3 streams at the same time and still have spare capacity.

My own playing around on a 20 Mbps long line is I can do 5 or 6 HD streams with no stuttering.

The author of the above post is a thinkbroadband staff member. It may not constitute an official statement on behalf of thinkbroadband.
Standard User TheEulerID
(member) Fri 26-Jun-15 15:06:14
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Re: Speed of a fibre strand?


[re: PaulKirby] [link to this post]
 
There's a news story around about a 1Pbps test that's been done on a single strand, so it's perfectly believable. It's more a matter of the opt-electronic interfaces. Not just the speed of switching, but the number of different wavelengths of light that are used.

However, I've got rather more doubts about a fibre capable of running at 99.97% (in a vacuum) for two reasons. First, optical fibre is made of refractive glass (or the light won't actually stay in the fibre). A the speed of light is inversely proportional to the refractive index, all current mono mode fibre of which I'm aware runs at around two-thirds of the speed of light in a vacuum.

The second reason is that the speed of propagation of light in fibre has little to do with the carrying capacity. Yes, it has something to do with latency (round-trip time is about 1ms per 100km of fibre), but not the actual bandwidth. The latter depends on things like the speed of optoelectronic switching and dispersion which tends to "smear out" the waveform over a long distance.

I would not expect to see those hyper-high speeds used in the distribution network as they require seriously expensive optoelectronics. They will be confined to back haul where it makes sense. In the distribution network cost and power consumption matter, so I think it will be a long time, if ever, before we see peta-bit/s capable fibre run into people's homes. After all, most domestic LANs tend to top out at 1gbps, let alone what WiFi delivers.
Standard User PaulKirby
(experienced) Fri 26-Jun-15 15:12:46
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Re: Speed of a fibre strand?


[re: MrSaffron] [link to this post]
 
Oh I am aware of it all being contended I was just assuming it was a bit better LOL.

But yeah, I am sure it would be fine.

I have even seen phone poles that have the FTTP and have done for a few years now and cannot see any fibres going to the homes, so maybe they either are not aware of fibre down their road even though BTOR have stapled a leaflet on each pole saying fibre is here etc.

Lets hope everyone else orders option 1 or 2 LOL.

I am probably just being over paranoid and worrying over nothing.

As for UHD TV's I was tempted in buying one a few months ago, but decided on waiting until content becomes more available etc.

I will be mostly using our connection for game development for downloading and uploading our content files that go into around ~3GB which I cannot do over our ADSL2+ connection, so sending loads of burnt DVD's LOL, where when our FTTP finely goes live I would be able to upload it instead.

Paul
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