MPLS broadband

Discussion in 'Broadband' started by Duncan Newell, Jun 18, 2004.

  1. Hi

    Can someone please explain (technically) how Multi Protocol Label Switching
    (MPLS) broadband works, at work we have had this installed so remote sites
    to us connect back to us, BT describe it as a form of broadband but
    apparently it has no contention ratio as its direct. Does anyone know how
    it works, is it just routed ? BT seem to be installing normal lines that are
    enabled for broadband ( so the engineers think ) also do these work same as
    ADSL so they can use a phone on line as well ?


    Duncan Newell, Jun 18, 2004
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  2. Duncan Newell

    Sunil Sood Guest

    Have a read of

    Sunil Sood, Jun 18, 2004
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  3. Interesting FAQ. Do you know is this connected up the same at the exchange
    end as if it was ADSL or differently ?

    Duncan Newell, Jun 18, 2004
  4. Duncan Newell

    Guest Guest

    I know what MPLS is (and have used implementations from BT and other
    suppliers) and I know what broadband is. But what is MPLS broadband? DSLAM
    as a label switching router?

    Guest, Jun 18, 2004
  5. Duncan Newell

    Ian Stirling Guest

    Answering in the general, I have no specific knowledge on this.
    In principle, ADSL can be set up in many ways.
    All of the varying services, from SDSL 2Mb/2Mb symmetric to ADSL 8Mb/256K
    to ... are simply a connection back to the exchange.
    There can be a phone connection installed at the same time over the
    same line, or the phone bit can be turned off (this is usually done during
    engineer installs, and the phone enabled seperately).

    From there, the data goes over internal circuits in the exchange to
    either BT IP-based networks, back to the ISP (or other end) or
    rented ATM network capacity.

    The ADSL connection to the exchange is little more than a means of
    transferring an ATM network connection back over the phone line to the
    This is very, very flexible, and in principle could support all sorts of
    services, for example being able to make private connections that do
    not go over the wider internet to multimedia services (at the same time
    that an internet conneciton is active to the ISP), or being able to
    access different ISPs when yours goes down, or being able to make
    data calls of a specified bandwidth to any similarly equipped subscriber.

    However, some of these possibilities are ruled out either by BT
    network design, or policy.
    Ian Stirling, Jun 18, 2004
  6. Duncan Newell

    Steve Guest

    It sounds like a IP-VPN based on MPLS (using RFC2547bis). The normal
    lines you describe are access lines to the edge (PE) router.

    This is a nice overview:
    Steve, Jun 18, 2004
  7. Duncan Newell

    Tom Buchanan Guest

    Tom Buchanan, Jun 19, 2004
  8. Duncan Newell

    shope Guest

    i work on a similar system.

    The BT DSLAM has a backhaul via ATM or IP - which is used depends on how the
    service was implemented by whoever provides the link - not sure if they are
    separate connections or not.

    our ADSL links to MPLS use ATM - it gives more control over contention
    ratios, without having to limit IP MTU, and doesnt need to touch BTs IP

    so - typical use of an ADSL access line to get to MPLS in this case is:

    LAN - CE router --- ADSL - DSLAM -- ATM -- PE router - MPLS core.

    So the ADSL link to the DSLAM just carries IP over ATM as for normal BT
    service (i think the ATM varient is called Datastream). any actual label
    switching for MPLS happens from PE to PE and doesnt affect the ADSL link.

    Have a look at SIN 347 on the BT specs web site
    shope, Jun 19, 2004
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