FTTC predicted speeds

I currently get a 3.7 Mbps ADSL synch rate with a BRAS of 3 Mbps.

The BT ADSL checker suggests that the maximum BRAS I can get on my line is 2
Mbps.

It says that I can expect a FTTC speed of 28 Mbps upstream.

What I don't understand is this: it predicts that some people who I know and
who get a better current ADSL synch rate than me (predicted and actual) will
get a lower FTTC connection than I will get.

Is this just poor prediction or is there a quality of FTTC that can boost
poor current ADSL connections above good current connections?

In article <p7adncakhdQAeHPRnZ2dnUVZ8v-(E-Mail Removed)>,
Peter Crosland <(E-Mail Removed)> wrote:

>The speed with FTTC depends on how close you are to the cabinet.

Where are these cabinets? All the phone lines around here go to
poles and then appear to disappear into the ground. Do they
install the cabinets when an exchange is enabled for FTTC, or are
they lurking in the bushes somewhere?

-- Richard

"Richard Tobin" <(E-Mail Removed)> wrote in message
news:icmvkk$ici$(E-Mail Removed)...
> In article <p7adncakhdQAeHPRnZ2dnUVZ8v-(E-Mail Removed)>,
> Peter Crosland <(E-Mail Removed)> wrote:
>
>>The speed with FTTC depends on how close you are to the cabinet.
>
> Where are these cabinets? All the phone lines around here go to
> poles and then appear to disappear into the ground. Do they
> install the cabinets when an exchange is enabled for FTTC, or are
> they lurking in the bushes somewhere?
>

In my area can't get anyone to say when FTTC will happen and I'm in a City
and not out in the middle of no where, the BT/Open Reach voting site which I
went to has 8 people voting, now 9 because of mine. Found out by accident
of this vote, think it a secret, from what I gather exchanges with most
votes get FTTC first.
I'm like you what ever is the alternative to cabinets here is under a large
GPO concrete double man hole cover.
Virgin Media have placed their cabinets on the pavements against garden
walls, probably BT will do the same.

I'm hoping that Fibre will replace the copper as I asked the Open Reach man
where my copper wire went I found out it goes in the opposite direction to
where the exchange is and is over twice the length than the crow flies to
the exchange
Regards
David

On Fri, 26 Nov 2010 07:55:17 -0000, "Peter Crosland"
<(E-Mail Removed)> wrote:

>BT Cabinets can be above or below ground.

I've never heard of underground cabinets before? Are you sure that
you are not getting confused with pavement joint boxes or underground
jointing chambers.

The difference is that in a cabinet all the wires in the exchange
side/ local side cables are exposed, so that every Tom, Dick or Harry
can work on them easily.

It a joint box / jointing chamber (and the cable chamber in the
exchange) there are never any loose wires. All the cables are sealed
in water and air tight sleeves, and it is a much bigger job to get
into them and make changes.

Ian
--
The From and ReplyTo addresses are valid

"IanB" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> On Fri, 26 Nov 2010 07:55:17 -0000, "Peter Crosland"
> <(E-Mail Removed)> wrote:
>
>>BT Cabinets can be above or below ground.
>
> I've never heard of underground cabinets before? Are you sure that
> you are not getting confused with pavement joint boxes or underground
> jointing chambers.
>
> The difference is that in a cabinet all the wires in the exchange
> side/ local side cables are exposed, so that every Tom, Dick or Harry
> can work on them easily.
>
> It a joint box / jointing chamber (and the cable chamber in the
> exchange) there are never any loose wires. All the cables are sealed
> in water and air tight sleeves, and it is a much bigger job to get
> into them and make changes.
>
Thanks for that explanation of what was used before cabinets came along on
top of the ground.
In my case these underground places are very common the concrete cover is
about 3 ft x 2 ft and at one road junction on the estate is a double one.
Can one assume the new cabinets will be on the ground adjacent to these
underground connection places.
VM have far less cabinets than the GPO covers.
Regards
David

On Fri, 26 Nov 2010 09:55:30 -0000, "David" <(E-Mail Removed)>
wrote:

>Thanks for that explanation of what was used before cabinets came along on
>top of the ground.

I think you may have misunderstood; cabinets and jointing places are
still both used in the network.

A cabinet is a cross-connection point. Where pairs coming from the
exchange can _easily_ by connected to pairs heading towards the
customer.

Jointing places are used for more permanent changes.

Very simplified; say you have a large (2000 pair or so) cable coming
from the exchange. At some point this is split and, say, 4 500 pair
cables head off in different directions. Each of those may end up in
a cabinet, or may be split (at different places along the route
perhaps) into further 100 pair cables. Some of those 100 pairs may go
to other cabinets, others may be split into 20 pairs that go to DPs
(up poles for example).

The same thing happens the other side of the cabinet. A 100 pair may
head off from the cabinet into a housing estate where it is split into
smaller cables that end up at DPs.

Each of the "splits" mentioned above needs a watertight joint. These
are located either in large chambers, smaller footway/road boxes or,
in many cases, are just buried under verges.

If you expand the above scenario many fold, exchanges can have 10s of
large cables leaving them, then you can see why there are so many
joint places around.

Ian
--
The From and ReplyTo addresses are valid

"IanB" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> On Fri, 26 Nov 2010 09:55:30 -0000, "David" <(E-Mail Removed)>
> wrote:
>
>>Thanks for that explanation of what was used before cabinets came along on
>>top of the ground.
>
> I think you may have misunderstood; cabinets and jointing places are
> still both used in the network.
>
> A cabinet is a cross-connection point. Where pairs coming from the
> exchange can _easily_ by connected to pairs heading towards the
> customer.
>
> Jointing places are used for more permanent changes.
>
> Very simplified; say you have a large (2000 pair or so) cable coming
> from the exchange. At some point this is split and, say, 4 500 pair
> cables head off in different directions. Each of those may end up in
> a cabinet, or may be split (at different places along the route
> perhaps) into further 100 pair cables. Some of those 100 pairs may go
> to other cabinets, others may be split into 20 pairs that go to DPs
> (up poles for example).
>
> The same thing happens the other side of the cabinet. A 100 pair may
> head off from the cabinet into a housing estate where it is split into
> smaller cables that end up at DPs.
>
> Each of the "splits" mentioned above needs a watertight joint. These
> are located either in large chambers, smaller footway/road boxes or,
> in many cases, are just buried under verges.
>
> If you expand the above scenario many fold, exchanges can have 10s of
> large cables leaving them, then you can see why there are so many
> joint places around.
>

Yes I can understand that, but the 2 pairs that leave my house and go
overhead to one of the 2 poles in my street go down inside the hollow pole
into the ground to be underneath the concrete man cover not to a cabinet so
what you give as jointing will be equivalent to a cabinet.
So if Fibre does some time in the long distant future come along I guess a
cabinet will appear some where to connect to my copper wire.
Regards
David.

On Fri, 26 Nov 2010 10:48:05 -0000, "David" <(E-Mail Removed)>
wrote:

>Yes I can understand that, but the 2 pairs that leave my house and go
>overhead to one of the 2 poles in my street go down inside the hollow pole
>into the ground to be underneath the concrete man cover not to a cabinet so
>what you give as jointing will be equivalent to a cabinet.

No, it's a joint. The cable going down your pole will be jointed into
a larger cable that is passing along your street. This will, possibly
via further joints, eventually get back to a cabinet*. _That_
location is where the fibre cabinet will _probably_ be placed.

A cabinet can be visited, and changes made, multiple times per day. It
is designed as an accessible cross-connection point, as is the MDF
(Main Distribution Frame) in the exchange.

On the other hand, once a joint has been provided it may never be
looked at again.

*Unless you are very close to the exchange.

Ian
--
The From and ReplyTo addresses are valid

On 26/11/10 11:05, IanB wrote:

> No, it's a joint. The cable going down your pole will be jointed into
> a larger cable that is passing along your street. This will, possibly
> via further joints, eventually get back to a cabinet*. _That_
> location is where the fibre cabinet will _probably_ be placed.

I hope BT might install extra fibre cabinets. Here in the London
suburbs I'm fed from a pole, and the nearest cabinet that I have found
is about a mile away :-(

Gareth wrote:
> I currently get a 3.7 Mbps ADSL synch rate with a BRAS of 3 Mbps.
>
> The BT ADSL checker suggests that the maximum BRAS I can get on my line
> is 2 Mbps.
>
> It says that I can expect a FTTC speed of 28 Mbps upstream.
>
> What I don't understand is this: it predicts that some people who I know
> and who get a better current ADSL synch rate than me (predicted and
> actual) will get a lower FTTC connection than I will get.
>
> Is this just poor prediction or is there a quality of FTTC that can
> boost poor current ADSL connections above good current connections?

FTTC (aka VDSL) runs out of steam rapidly on lines longer than 1km, but less
than 1km speeds hold up very well. I'm 800 metres from my FTTC cabinet as the
crow flies, and I estimate the actual line length must be at least a km.

BT predicted 14.7 Mb/s for me, but the reality is a 34 Mb/s sync rate, and a
typical 'best case' d/l speed of 28-29 Mb/s. Reading the ThinkBroadband
forums, most people with predictions of 20 or less, seem to be getting double
the BT estimates in terms of sync on FTTC connections, though of course the
max sync is currently 40 Mb/s (with overheads probably max actual d/l is 36 ish).

However AIUI VDSL suffers far more than ADSL from crosstalk, so if you're the
only person on a multicore with VDSL then great, but once all your neighbours
get it, perhaps the BT estimates won't seem so pessimistic ?


--
Mark
Please replace invalid and invalid with gmx and net to reply.

www.paras.org.uk