FTTC predicted speeds

Discussion in 'Broadband' started by Gareth, Nov 25, 2010.

  1. Gareth

    Gareth Guest

    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

    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?
    Gareth, Nov 25, 2010
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  2. 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, Nov 26, 2010
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  3. Gareth

    David Guest

    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
    David, Nov 26, 2010
  4. Gareth

    IanB Guest

    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.

    IanB, Nov 26, 2010
  5. Gareth

    David Guest

    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.
    David, Nov 26, 2010
  6. Gareth

    IanB Guest

    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

    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.

    IanB, Nov 26, 2010
  7. Gareth

    David Guest

    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.
    David, Nov 26, 2010
  8. Gareth

    IanB Guest

    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.

    IanB, Nov 26, 2010
  9. 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 :-(
    Andrew Benham, Nov 26, 2010
  10. Gareth

    Mark Carver Guest

    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 Carver, Nov 27, 2010
  11. Gareth

    alexd Guest

    Meanwhile, at the uk.telecom.broadband Job Justification Hearings, Mark
    chose the tried and tested strategy of:
    See if they've got a LocalView on the internet. My council does, and I used
    the 'Planning Applications' layer on the map to determine that the plinth
    for an active cab that had appeared nearby was [alas] a new mobile mast and
    not FTTC.
    alexd, Nov 30, 2010
  12. Gareth

    Paulg0 Guest

    Your local cabinets should look something like the ones here:


    Paulg0, Dec 3, 2010
  13. Gareth

    Mark Carver Guest

    Same here, almost certainly the same layout inside, because snow has only
    settled on the right hand third of the top ;-)
    Mark Carver, Dec 4, 2010
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