Telecom speed throttling

Discussion in 'NZ Computing' started by whome, Oct 4, 2006.

  1. whome

    whome Guest

    I've noticed that when I exceed my bandwidth cap, Telecom restrict me to
    65kbps.

    However, I've noticed that when throttled that webpages sometimes get
    'stuck' for a while.

    Eg, loading the herald webpage will load a few bits onto the screen , then
    freeze for a while before loading the rest of the webpage. In fact, it
    seems slower than on dialup.

    Does telecom do something more than just reducing the speed to 65kbps? eg,
    introduce 'freezes' ?
     
    whome, Oct 4, 2006
    #1
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  2. "whome" <> wrote in message
    news:...
    > I've noticed that when I exceed my bandwidth cap, Telecom restrict me to
    > 65kbps.
    >
    > However, I've noticed that when throttled that webpages sometimes get
    > 'stuck' for a while.
    >
    > Eg, loading the herald webpage will load a few bits onto the screen , then
    > freeze for a while before loading the rest of the webpage. In fact, it
    > seems slower than on dialup.


    Well.. to tell the truth.. a Dialup modem downloading normal webpages can
    be faster than a rate limited 64K DSL line.. You don't think so?

    A Dialup Modem has compression so text (webpages) can download faster
    than the DSL connection can so a Dialup Modem may seem faster (as a DSL
    router has no compression over the connection)

    Another problem you might find is the HTTP protocol will only download 2
    things at a time in parrallel from a single domain name (yes I know strange
    but its what the specs say) (IE6 by default will do this).

    So if you have webpage with 10 images it cannot download all at the same
    time
    to view. Over a slower connection this makes sense, with higher speed
    it is alittle anoying)

    Thanks
    Craig
     
    Craig Whitmore, Oct 4, 2006
    #2
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  3. whome

    whome Guest

    "Craig Whitmore" <> wrote in message
    news:45238b6e$...
    >
    > "whome" <> wrote in message
    > news:...
    >> I've noticed that when I exceed my bandwidth cap, Telecom restrict me to
    >> 65kbps.
    >>
    >> However, I've noticed that when throttled that webpages sometimes get
    >> 'stuck' for a while.
    >>
    >> Eg, loading the herald webpage will load a few bits onto the screen ,
    >> then freeze for a while before loading the rest of the webpage. In
    >> fact, it seems slower than on dialup.

    >
    > Well.. to tell the truth.. a Dialup modem downloading normal webpages can
    > be faster than a rate limited 64K DSL line.. You don't think so?
    >
    > A Dialup Modem has compression so text (webpages) can download faster
    > than the DSL connection can so a Dialup Modem may seem faster (as a DSL
    > router has no compression over the connection)
    >
    > Another problem you might find is the HTTP protocol will only download 2
    > things at a time in parrallel from a single domain name (yes I know
    > strange
    > but its what the specs say) (IE6 by default will do this).
    >
    > So if you have webpage with 10 images it cannot download all at the same
    > time
    > to view. Over a slower connection this makes sense, with higher speed
    > it is alittle anoying)
    >
    > Thanks
    > Craig
    >
    >
    >


    Well, my dial-up certainly seemed faster than the throttled ADSL.

    Does ADSL not use compression? I would have thought so.
     
    whome, Oct 4, 2006
    #3
  4. whome

    David Guest

    whome wrote:
    > "Craig Whitmore" <> wrote in message
    > news:45238b6e$...
    >> "whome" <> wrote in message
    >> news:...
    >>> I've noticed that when I exceed my bandwidth cap, Telecom restrict me to
    >>> 65kbps.
    >>>
    >>> However, I've noticed that when throttled that webpages sometimes get
    >>> 'stuck' for a while.
    >>>
    >>> Eg, loading the herald webpage will load a few bits onto the screen ,
    >>> then freeze for a while before loading the rest of the webpage. In
    >>> fact, it seems slower than on dialup.

    >> Well.. to tell the truth.. a Dialup modem downloading normal webpages can
    >> be faster than a rate limited 64K DSL line.. You don't think so?
    >>
    >> A Dialup Modem has compression so text (webpages) can download faster
    >> than the DSL connection can so a Dialup Modem may seem faster (as a DSL
    >> router has no compression over the connection)
    >>
    >> Another problem you might find is the HTTP protocol will only download 2
    >> things at a time in parrallel from a single domain name (yes I know
    >> strange
    >> but its what the specs say) (IE6 by default will do this).
    >>
    >> So if you have webpage with 10 images it cannot download all at the same
    >> time
    >> to view. Over a slower connection this makes sense, with higher speed
    >> it is alittle anoying)
    >>
    >> Thanks
    >> Craig
    >>
    >>
    >>

    >
    > Well, my dial-up certainly seemed faster than the throttled ADSL.
    >
    > Does ADSL not use compression? I would have thought so.
    >
    >


    No, when you take into account the fact that ADSL is designed to
    function at high speeds, at least 1mbit ( and New Zealand is probably
    the only place where it is throttled to anything less than that )
    compression becomes a waste of resources, and may even slow down the
    connection, due to the volume of data passing through. Also, these days
    most data is uncompressible (images, video etc) and many webservers will
    gzip compress web pages if your browser supports it.
     
    David, Oct 4, 2006
    #4
  5. whome

    whome Guest

    >>
    >> Well, my dial-up certainly seemed faster than the throttled ADSL.
    >>
    >> Does ADSL not use compression? I would have thought so.

    >
    > No, when you take into account the fact that ADSL is designed to function
    > at high speeds, at least 1mbit ( and New Zealand is probably the only
    > place where it is throttled to anything less than that ) compression
    > becomes a waste of resources, and may even slow down the connection, due
    > to the volume of data passing through. Also, these days most data is
    > uncompressible (images, video etc) and many webservers will gzip compress
    > web pages if your browser supports it.



    Well, hardware compression of the communications stream would surely be
    pretty quick?

    This is all the phoneline modems do.

    You are right about images/video - they are already compressed to the nth
    degree so hardware compression in the adsl modem would have little effect.

    And, the point of the previous poster was that phone modem compression
    speeds up webpage loading - I could see this working OK for text, but not
    for already compressed data.
     
    whome, Oct 5, 2006
    #5
  6. whome

    David Guest

    whome wrote:
    >>> Well, my dial-up certainly seemed faster than the throttled ADSL.
    >>>
    >>> Does ADSL not use compression? I would have thought so.

    >> No, when you take into account the fact that ADSL is designed to function
    >> at high speeds, at least 1mbit ( and New Zealand is probably the only
    >> place where it is throttled to anything less than that ) compression
    >> becomes a waste of resources, and may even slow down the connection, due
    >> to the volume of data passing through. Also, these days most data is
    >> uncompressible (images, video etc) and many webservers will gzip compress
    >> web pages if your browser supports it.

    >
    >
    > Well, hardware compression of the communications stream would surely be
    > pretty quick?
    >
    > This is all the phoneline modems do.
    >


    There is a difference between compression at 50kbps (probably done by
    the drivers on your powerful computer with modern 'winmodems') and
    compression at many megabits done by the shittiest cheapest DSE router.

    > You are right about images/video - they are already compressed to the nth
    > degree so hardware compression in the adsl modem would have little effect.
    >
    > And, the point of the previous poster was that phone modem compression
    > speeds up webpage loading - I could see this working OK for text, but not
    > for already compressed data.
    >
    >
     
    David, Oct 5, 2006
    #6
  7. whome

    Phil Guest

    Craig Whitmore wrote, On 4/10/06 11.17 p:
    > A Dialup Modem has compression so text (webpages) can download faster
    > than the DSL connection can so a Dialup Modem may seem faster (as a DSL
    > router has no compression over the connection)


    The compression on dial-up was just a feature of PPP. Since DSL operates
    over PPPoA, I'd image that'd still be there (assuming your router and
    whoever's PPP server you to supports it).

    -Phil
     
    Phil, Oct 5, 2006
    #7
  8. whome

    EMB Guest

    Phil wrote:

    > The compression on dial-up was just a feature of PPP. Since DSL operates
    > over PPPoA, I'd image that'd still be there (assuming your router and
    > whoever's PPP server you to supports it).


    The compression on dial-up is a feature of the V.42bis (and later V.44)
    ITU standards.

    --
    EMB
     
    EMB, Oct 5, 2006
    #8
  9. whome

    David Empson Guest

    Phil <> wrote:

    > Craig Whitmore wrote, On 4/10/06 11.17 p:
    > > A Dialup Modem has compression so text (webpages) can download faster
    > > than the DSL connection can so a Dialup Modem may seem faster (as a DSL
    > > router has no compression over the connection)

    >
    > The compression on dial-up was just a feature of PPP.


    PPP has its own minor compression techniques, which save a few bytes per
    frame (e.g. eliminating some IP header fields which are fixed due to the
    point-to-point nature of the link). This is known as Van-Jacobsen Header
    Compression. This has no effect on the body of the frame (the data you
    are actually sending and receiving).

    The dialup modem itself typically has error compression and data
    compression enabled (V.42 error correction with V.42bis data
    compression). This works on individual bytes being sent through the
    modem, scanning them for repeated patterns, which are compressed. In
    ideal conditions, this can achieve almost 4:1 compression of repetitive
    data on an error-free link. For plain text, a compression ratio of 2:1
    is quite common.

    The modem connection simply appears like a faster serial connection
    (with somewhat variable average speed due to varying compression ratios
    and possible errors), and PPP runs over that.

    > Since DSL operates over PPPoA, I'd image that'd still be there (assuming
    > your router and whoever's PPP server you to supports it).


    I'm not very familiar with PPPoA. Assuming it has the same protocol
    features as PPP, just running over a different transport, then it should
    support the VJ header compression techniques, which only saves a few
    bytes per frame. The data within the frames (i.e. the content of what
    you are sending) is not compressed by PPPoA, same as for PPP over
    dial-up modems.

    --
    David Empson
     
    David Empson, Oct 5, 2006
    #9
  10. whome

    jasen Guest

    On 2006-10-05, Phil <> wrote:
    > Craig Whitmore wrote, On 4/10/06 11.17 p:
    >> A Dialup Modem has compression so text (webpages) can download faster
    >> than the DSL connection can so a Dialup Modem may seem faster (as a DSL
    >> router has no compression over the connection)

    >
    > The compression on dial-up was just a feature of PPP. Since DSL operates
    > over PPPoA, I'd image that'd still be there (assuming your router and
    > whoever's PPP server you to supports it).


    nope. "CCITT V.42 bis" also.

    > -Phil



    --

    Bye.
    Jasen
     
    jasen, Oct 6, 2006
    #10
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