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Standard User j0el
(newbie) Thu 04-Oct-18 00:03:56
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Re: How fast can the cabinets go?


[re: nemeth782] [link to this post]
 
In reply to a post by nemeth782:
It's also why VDSL2+ 17a could never even achieve the theoretical max - OFCOM won't let them reuse the ADSL frequencies from the cabinet because it might cause crosstalk for ADSL customers so VDSL has to be "notched".

VDSL2 VPlus/35b is not 17 MHz, but rather 35 MHz. We currently use 17a, not 35b, and VDSL2 VPlus does not exist in 17a variant, but can co-exist with pre-existing 17a deployments.

In reference to ADSL and VDSL overlay, Power Spectral Density (PSD) masks are in place to "protect" ADSL signals from being impacted from VDSL. Of course, this impacts VDSL performance (and sadly, I don't know by how much).

In reply to a post by nemeth782:
G.Fast is notched to 17mhz so as not to interfere with VDSL2, and if they deployed VDSL2+ it would end up reducing the maximum speed of G.Fast.

The starting frequency of G.fast is actually 19 MHz in Openreach deployments, and uses the range 19-106 MHz currently. As you are aware, this is to reduce the impact of G.fast on VDSL 17a.

VDSL 35b won't be rolled out because the density is less compared to 17a and because it would probably cost a lot more money than worth at this point as I cannot remember if vendors have compatibility with 35b profile with the current hardware rolled out across the UK.

In reply to a post by nemeth782:
If they just replaced one product with the next, VDSL syncs would be about 10mbit higher (from the use of the ADSL frequencies) and G.Fast where available would get ~60-70m higher syncs than it does. All they need to do is turn off the old product and move everyone on that node onto the new one.

If it could use all the frequencies, VDSL would never perform worse than ADSL, and G.Fast would always be at least as fast as VDSL, etc.

Aggressively curtailing older technologies would be the best case for increasing speeds/freeing up bandwidth among newer technologies that use radio frequencies. It is essentially the same premise for mobile networks, TV and radio too as what happened with the digital switchover, adjustments in the TV broadcasting frequencies for 4G, etc.

As you said previously, providers have investments in ADSL2+ technologies. Sky and TalkTalk in particular have a huge LLU presence. This was a lot of money invested into their network. Phasing out technologies is not just a problem of moving people over to the newer technologies, but is also a financial issue.

Edited by j0el (Thu 04-Oct-18 00:06:00)

Standard User Ignitionnet
(knowledge is power) Thu 04-Oct-18 14:12:28
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Re: How fast can the cabinets go?


[re: RobertoS] [link to this post]
 
In reply to a post by RobertoS:
ADSL Max did not maximise the line smile. It was capped at 8128/448kbps though there was an option not all ISPs offered of 8128/832kbps.

8Mbps is 8192kbps.


8Mbps is 8,000kbps or if you prefer 8,000,000 bits per second. Communications speeds use base 10 not binary / base 2. You can read various gack on this but the fact that Gigabit Ethernet is 1 billion bits per second and Fast Ethernet 100 million bits per second per the IEEE standards should suffice.

Pedantic I know but that's the price you pay for being a serial pedant. Karma smile

----
Building better networks, not just faster ones.
Standard User RobertoS
(elder) Thu 04-Oct-18 16:52:29
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Re: How fast can the cabinets go?


[re: Ignitionnet] [link to this post]
 
You're right of course. Mea culpa.

However my version does fit the accepted one for ADSL Max. And the correct version only invalidates that final sentence of my post. The main content is true smile.

Plus, on O2/Be and other LLU systems all of which were on ADSL2+ DSLAMs in those days, the 8Mbs options all sync'ed at "up to" 8192kbps.

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