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Standard User David_W
(fountain of knowledge) Sun 27-Oct-13 23:25:56
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Re: FTTC modem cable question?


[re: Routefinder] [link to this post]
 
In reply to a post by Routefinder:
So just to clarify ~ Fibre Broadband if you are lucky depending on contract gets a max 80Mbps download speed to the modem and the 2 pair CAT5 is OK up to 100Mbps so is that rather a no brainer for any users of FTTC services as though the internal network can be Gigabit (as some of my connections are ~ my NAS and main PC are Gigabit and I use a Gigabit switch to connect them and the switch to the Router which is not Gigabit) the fact that at the Modem you currently, indeed for the quite long term foreseeable future, can only get the 80Mbps???
A 2 pair connection on pins 1/2 and 3/6 is sufficient for 100 Mbit/s Ethernet but not faster. Gigabit Ethernet needs all four pairs.


VDSL2 Profile 17a, which Openreach currently use for FTTC, has a raw data rate maximum of around 250 Mbit/s split between upstream and downstream. Without getting too mired down in detail, it's possible for short lines to manage a small amount over 100 Mbit/s in the downstream direction on the current setup, but Openreach do not currently market any FTTC services faster than 80/20 Mbit/s. The current Openreach modems only have 100 Mbit/s Ethernet ports.

It's possible that Openreach FTTC may move to Profile 30a in the future, with a raw data rate maximum of just over 400 Mbit/s split between upstream and downstream. This is by no means certain to happen, as the costs may outweigh the benefits. I believe all the current Openreach modems lack Profile 30a support, and most if not all of the currently deployed line cards in the cabinets lack Profile 30a support. It is only the best quality lines, usually the shortest ones, that will gain a significant speed boost from Profile 30a. Any Profile 30a equipment is likely to use Gigabit Ethernet.

I'm not sure whether Profile 17a and Profile 30a can run side by side on the same infrastructure. Openreach currently use the B8-11 band plan with the optional US0 band specified (BT SIN 498 paragraph A1.1.1 refers). The Profile 30a B8-16 band plan looks compatible, but I don't have a deep enough insight into the issues to know whether side by side Profile 17a and 30a operation is practical, especially when you throw in the complications of vectoring.


FTTP equipment already uses Gigabit Ethernet.


Ultimately, a 2 pair cable will prove limiting, but how soon you will meet that limit is uncertain. My FTTC connection runs at the full 80/20 Mbit/s, and I doubt I would notice the difference with a slightly faster connection other than on a speed test.


As you've found, 2 pair cable versus 4 pair cable might be an academic argument anyway, considering that 2 pair cable is likely to be akin to the proverbial rocking horse droppings.

At least some versions of the BT Data Extension Kit used to provide the Home Wiring Solution on FTTC installations were reputed to use 2 pair Category 5e cable. Maybe someone can confirm this, especially whether the kits currently available contain 2 pair cable.

Standard User Routefinder
(experienced) Mon 28-Oct-13 00:59:05
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Re: FTTC modem cable question?


[re: David_W] [link to this post]
 
Hi David

Many thanks for the insight smile I have sent an enquiry to Clarity about suitability of the kit mentioned above, though what you say does point to it being fine for the foreseeable future.

FWIW as far as I can tell we are approx. 400M from the PCP cabinet and hence approx. the same distance from the FTTC cabinet once it is installed. Somewhere....was here at TBB or Kitz there is a table that from memory suggested we should see max 36Mbps download speed???
Standard User 4M2
(knowledge is power) Mon 28-Oct-13 01:20:07
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Re: FTTC modem cable question?


[re: Routefinder] [link to this post]
 
There is another thing to bare in mind: all-in-one modem/routers are starting to be supplied by FTTC providers. We have been considering an ethernet link between modem and router and if you were to use a modem/router then a 2 pair CAT5e cable would only carry up to 100Mbps to the office equipment…

http://www.thinkbroadband.com/guide/fibre-broadband.... - 400 metres ~42/16Mbps smile


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Standard User eckiedoo
(committed) Mon 28-Oct-13 07:44:32
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Re: FTTC modem cable question?


[re: Routefinder] [link to this post]
 
Thanks for that link, Routefinder, ties in with my experience.

I would suggest that the Joint was "invented" in several locations, almost simultaneously, probably in conjunction of the early railways here in Britain, as generally there was a requirement in their Parliamentary Acts for them to be fenced etc for the protection of livestock; and thus significantly different from general overseas practice.

That would lead on to the use on telegraph wiring, of which the railways were early proponents.

----------------------------------

Agreed that it is more suited to single strand, hard-drawn copper wire rather than stranded, especially multi-stranded; but it does have its uses in other situations. (No good on Litz wire!)

For example, about two weeks back, I wanted to join two pairs of multi-stranded cable, making sure that they were well-connected due to the current involved.

I first found a short section of large "chocolate block" (multi-way screw connector, generally white plastic today), slackening the screws to leave the holes through the brass unions unobstructed.

I threaded two of the wires right through two of the brass unions, extending about three inches on the far side.

Prepared the ends of all four wires; connecting the required pairs by short PO Joints.

I pulled those Joints into the holes through the brass segments, with the wire insulation just entering neatly at the respective portals.

Tightened up the screws, to give very robust splicing of the cables.

=================================

Taking the OP's original modus operandi, if he initially removed a length of the outer insulation by slitting longitudinally, (resulting in a miniature version of the circular, slitted foam tubes for insulating pipes); he could fit that outer insulation over the full jointing length, resulting in a neat way of extending such cables, with almost "invisible" joints.

Incidentally, those foam tubes can be useful to tidy up a collection of cables; and also fitted over the tubes of garden furniture to make them more comfortable.
Standard User Routefinder
(experienced) Sat 02-Nov-13 18:17:33
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Re: FTTC modem cable question?


[re: eckiedoo] [link to this post]
 
Well as mentioned following on from 4M2's suggestion I emailed Clarity using their "contact page" on the 28th October...........................and have yet to receive a reply, to say the least that does not inspire confidence in regard to dealings with the company??? I thought I would phone them on Monday but cannot find a phone number anywhere on the site???

FWIW here is the content of the message I sent them:-

Hi

I hope you can advise me.

We currently have a Max DSL service but we are due to have FTTC in the area by the end of this year so I am doing some forward planning.

For my current setup I use CW1308 UTP phone cable to link between my master socket and my Router in my home office on the floor above. The CW1308 is pulled through the ceiling & floor but the holes are not directly aligned, there is a lateral displacement of approx. 8 inches. The holes in the ceiling and floor just fit the CW1308 but there is still some freedom of movement.

In preparation for the FTTC coming I was hoping to replace the CW1308 cable with CAT5e to link the BTOR Modem and the new Fibre Router but my problem is that moving the furniture and lifting floorboards is not currently an option! I have found some 4 pair CAT5e that is 5.25mm diameter but that may be pushing my luck when using the old cable to pull through that size of CAT5e.

I asked over at Think Broadband Forum and someone suggested that as the BTOR Modem is only 100Mbps output that 2 pair CAT5e would be sufficient and linked me to your website for this product BT Openreach Line Engineer's xDSL Extension Kit.

So based on the above criteria of access and pulling the 2 pair cable in the kit plus the need to meet the need for a proper connection between the BTOR Modem and the Router is the 2 pair CAT5e in the kit you sell suitable for the purpose???

Many thanks in anticipation of help and feedback with this question smile
Standard User dragon2611
(committed) Sun 03-Nov-13 16:06:00
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Re: FTTC modem cable question?


[re: David_W] [link to this post]
 
In reply to a post by David_W:
This assumes that you have power near your master socket to power the modem. I keep on meaning to get hold of a Power over Ethernet splitter capable of providing the correct voltage to the modem to see if I can power the modem remotely. Unfortunately, this is stuck on my lengthy "to do" list behind many other projects.


I Use a passive splitter/injector set with the original PSU for the HG612 and it seems to work, although thats over a fairly short run (Probably less than 10M)

Not tried an ECI and those I think have a slightly higher current draw
Standard User eckiedoo
(committed) Sun 03-Nov-13 21:07:04
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Re: FTTC modem cable question?


[re: Routefinder] [link to this post]
 
Almost certainly NOT applicable in your case; but the best way to make holes through wood for cable pulling etc, is to use a red-hot poker.

This gives a very smooth hole, with some carbon lubrication. The lignum melts initially, then hardens to form a "smooth liner".

I think it was the Admiralty Weapons Research Department which found this method best for spooling out wire at high-speed, during WW2.

Graphite was used as a dry lubricant on pianola "motors". In the absence of graphite, I have used talcum powder for that purpose!

Graphite was supplied and used to lubricate the wooden slide valves on the early, Link Trainer Flight Simulators, which had an air-powered "bellows" motor to rotate them for different compass headings.


Ancient memories!
Standard User Routefinder
(experienced) Sun 03-Nov-13 23:30:04
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Lubing the cable for pulling through.


[re: eckiedoo] [link to this post]
 
In reply to a post by eckiedoo:
Almost certainly NOT applicable in your case; but the best way to make holes through wood for cable pulling etc, is to use a red-hot poker.

This gives a very smooth hole, with some carbon lubrication. The lignum melts initially, then hardens to form a "smooth liner".

I think it was the Admiralty Weapons Research Department which found this method best for spooling out wire at high-speed, during WW2.

Graphite was used as a dry lubricant on pianola "motors". In the absence of graphite, I have used talcum powder for that purpose!

Graphite was supplied and used to lubricate the wooden slide valves on the early, Link Trainer Flight Simulators, which had an air-powered "bellows" motor to rotate them for different compass headings.


Ancient memories!


A good point you make about using a dry lubricant of some description..........a 3B pencil potentially would make a suitable graphite based one??? Or are pencils no longer almost 100% graphite, though possibly a tad messy to wipe down? As you say talc would work too smile
Standard User eckiedoo
(committed) Mon 04-Nov-13 07:25:56
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Re: Lubing the cable for pulling through.


[re: Routefinder] [link to this post]
 
A 3B pencil would probably suffice, bearing in mind that the corresponding 3H woulld have a lot of clay or similar in it - back to the HB's!

Just checked, they range to 10B!

But in your case, if you do open up the hole/s with a needle file or similar, that will tend to smooth the sides, so I would recommend the talcum powder, as it will probably clean up better.

================================

Avoid using "ordinary" pencils on PCB's, particularly if it is high-impedance circuitry, typical of thermionic valves (of ancient times).

The graphite is a conductor and can get in to the surface of the underlying strata.

No amount of cleaning will get it out, causing "invisible shorts"; and lots of head-scratching until I followed the whole process through in detail.

And the "cleaning" in itself could cause problems in addition to the "shorts", leading to scrapping.
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