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Author Topic: What's the difference between an ADSL and Fibre WiFi router?  (Read 11397 times)

vonsworld

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What's the difference between an ADSL and Fibre WiFi router?
« on: August 19, 2016, 10:28:22 AM »

Hello

I understand that the Fibre optic cable runs to the local BT cabinet and from there the connection to your house is through the usual copper wire. Therefore the cabinet acts like a mini exchange without the need for the broadband to run all the way back to the main exchange through copper wire, hence the significant improvement in speed.

In which case does a fibre router work in quite a similar way to an ADSL router? Is Fibre like having a short length ADSL connection from the cabinet?

Also does a fibre router connect to your BT line using the same ADSL filters/splitters?

Thanks in advance for any explanations  :)
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loonylion

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Re: What's the difference between an ADSL and Fibre WiFi router?
« Reply #1 on: August 19, 2016, 11:30:24 AM »

the primary difference is it's a different technology. ADSL is ADSL, using up to 2.2Mhz of tones on the phoneline. What is called 'fibre' is actually VDSL, using up to 30MHz (17 currently in the UK) of tones, so the significant speed increase isn't just down to the shorter copper, its also because there's a lot more tones available. VDSL modems in general will be backwards compatible, but ADSL modems are not forward compatible.

adsl filters will work but it's generally recommended to use a centralised filtered faceplate designed for vdsl rather than an adsl dangly filter.
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j0hn

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Re: What's the difference between an ADSL and Fibre WiFi router?
« Reply #2 on: August 19, 2016, 12:26:59 PM »

It's essentially the same type of technology as ADSL. Like said above it's actually called VDSL2. The word Fibre is essential a marketing trick. I like this example...

My friend lives about 100m from the local exchange and had ADSL on an exchange only line (no PCP cabinet at all). As part of the VDSL rollout they installed an FTTC cabinet in the car park of the exchange to serve all the local properties. This is 1 of the combined PCP/FTTC AIO cabinets. So he has the exact same amount of copper between the exchange and his home as before, but suddenly he now has "Superfast Fibre".

Other places in the world will serve VDSL from the exchange, and other places can serve ADSL from a cabinet. They are both essentially Fibre > DSLAM/MSAN > copper > your home.

The short answer to your question is yes, but it's not fibre, and it's not a fibre router. It's a VDSL router. It works in exactly the same way as ADSL, just on higher frequencies and with more tones.

ADSL1 and ADSL2 use frequencies up to 1.1 MHz
ADSL2+ use frequencies up to 2.2 MHz
VDSL2 (profile 17a) use frequencies up to 17MHz

ADSL1 and ADSL2 has 256 tones
ADSL2+ has 512 tones
VDSL2 (profile 17a) has 4096 tones

There are other differences like atm/ptm framing but it gets very technical, way over my head!
If your interested, these pages are a good read and do a good job at not over complicating things.

http://www.kitz.co.uk/adsl/adsl_technology.htm
http://www.kitz.co.uk/adsl/fttc.htm
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WWWombat

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Re: What's the difference between an ADSL and Fibre WiFi router?
« Reply #3 on: August 19, 2016, 03:09:11 PM »

The other replies concentrate on one difference between the broadband generations: ADSL, adsl2+ and VDSL2. They're right in those descriptions.

There is a further difference that can be implied when talking of a "fibre router": the physical cable connection.

As we understand ADSL service today, the "ADSL router" is actually a combined ADSL modem and a router that understands routing across the modem. A single physical connection exists - the phone line. Most people have stopped calling it a modem/router, and just use "router" as a shortcut.

As "fibre broadband" started up, there was no combined VDSL2 modem/router. Instead you had one box that was a VDSL2 modem (for FTTC) or a fibre NTE (for FTTP), and a separate standalone box as a router. This router has an Ethernet socket for the connection to the modem or NTE, often labeled EWAN. The router sends traffic out using the PPPoE (over Ethernet) protocol, while the modem figures out the stuff specific to the physical copper/fibre line.

So, a couple of years ago, the term "fibre router" meant one with an EWAN connector, that didn't understand VDSL2 at all. It could be used on either FTTC or FTTP.

Nowadays, we are starting to get a choice of combined VDSL2 modem/routers, which work in principle like the equivalent ADSL devices.

So... The term "fibre router" could then be used in the old way to show it has an EWAN connector and you need a separate modem, or could be used in a lazy way for the newer combined devices, where you need a phone line.

For a while, routers with an EWAN connection were more commonly called "cable routers". It was a bit weird buying a cable router to work with your FTTC connection.
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Weaver

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Re: What's the difference between an ADSL and Fibre WiFi router?
« Reply #4 on: August 20, 2016, 03:52:34 AM »

As an earlier poster said, using the word "fibre" to refer to FTTC is something that really annoys me, as IMHO it's just a marketing con and potentially misleading. Some of our esteemed users don't agree with me on this though, because engineers often see the world from the other end, from the exchange end, and in that view, they have indeed now got (more) fibre, from the exchange to the cab, so some BTOR staff understandably think "fibre" when FTTC is under discussion.
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