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Thread: One Way Internet - Virgin Media

  1. #1
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    One Way Internet - Virgin Media

    I saw this linked somewhere else and thought it might interest someone:

    It comes after a post about how the 50mbit connection could not work very well for most people unless their connection is set up properly, because when downloading, your connection needs to upload data to basically check that it downloaded properly. So downloading at 50mbit will send so much uploaded data, that it could create problems for some people, seeing as Virgin will only offer a 1.5mbit upload speed with that huge download speed, an all time new low standard with an upload worse than 34:1.

    That leads us to the next post.

    This is what it says:

    This update is a bit geeky, so apologies!

    I've been thinking... one defense that Virgin Media might offer is that the cable network wasn't really built for upstream traffic, but downstream, as you'd imagine from a network originally built to carry cable TV.

    We'll ignore that Virgin's advertising portrays their network as being especially built for broadband internet traffic, especially when you consider that on cable networks the downstream internet is carried inside Digital TV frames. We're looking at upstream and on upstream we'll stay.

    One way this defense falls apart that I alluded to is that ComCast in the USA are offering better ratios on their products but have less capacity to offer upstream. I'll explain this one along with a quick 'primer'.

    Everything on the cable network is carried over RF. Radio Frequency. Just like you tune your FM radio that's exactly what your cable modem and set top box do. They tune into a certain frequency on the cable network depending on what you ask and there's the signals. The arrangement of these frequencies is based on old analogue TV channels. In the US they use the analogue TV standard NTSC, here in the UK we use PAL. In the USA all the channels are 6MHz wide, in the UK they are 8MHz wide, and another difference is that in the UK we can divide our network between upstream and downstream differently. The first analogue TV channel that NTSC needs is on the frequency of 54-60MHz, and upstream and downstream can't share the same space, so in the USA they have to end all upstream signals at 42MHz. Here in the UK we don't have that channel and can run our upstreams right up to 65MHz. For a few reasons the upstreams start from 5MHz.

    It's a really simple sum the science bit aside, it actually comes down to this:

    USA - Maximum Upstream Bandwidth 37MHz.
    UK - Maximum Upstream Bandwidth 60MHz.

    So how come this happens:

    ComCast - Top Upstream on normal cable product: 2Mbit
    ComCast - Ratio on normal cable product: 4:1

    Virgin Media - Top Upstream on normal cable product: 768kbit
    Virgin Media - Ratio on normal cable product: >26:1

    Then we get to another point. Perhaps the 'equipment' isn't capable. This doesn't stand up either. ComCast have released a new 50Mbit product, Virgin have one on the way. These run this way on the upstream:

    ComCast - 50Mbit downstream, 5Mbit upstream, ratio 10:1
    Virgin Media - 50Mbit downstream, 1.5Mbit upstream, ratio >33:1

    It's also worth mentioning that the original equipment is capable of a better upstream ratio too. The equipment at the Virgin Media side was originally very similar to these. This isn't asymettrical at all. You can deliver more bandwidth upstream than downstream with these babies - depending on which Virgin Media area you are in you will get either 38Mbit or 51Mbit downstream on one of these line cards, they are capable of 6 channels each with 8.8Mbit = total 52.8Mbit upstream capacity.

    Virgin then moved to these in some areas. Notice less upstream to downstream ports, however these are actually capable of more bandwidth being more modern equipment. Even using the 'standard' configurations without doing anything special you can get worst case 51Mbit downstream and 35.2Mbit upstream in 4 8.8Mbit channels. These newer cards are, however, also capable of delivering a lot more upstream than this. With the right modems, which Virgin have been supplying for years, and some care taken with the cable network itself which is likely the key part, the upstream capacity can go from 8.8Mbit on each channel right up to 27Mbit. 51Mbit downstream, 108Mbit upstream assuming splitting the MC28U card evenly.

    The only real reason that Virgin may have for not being able to offer this kind of upstream is simple. They have not looked after their network properly, and the money hasn't been there to do maintenance nor upgrade very old areas of network and generally they've been content to do the bare minimum to keep things moving along. This assertion is supported by Virgin's own results which show a significantly lower overbuild spend than many of their peers worldwide.

    Virgin: You're a cable company. Stop believing your own advertising that you're fibre optic and spend the money needed to look after the network properly, not just the fibre optic parts but the copper as well. Without those you are in a green box somewhere in the street, but not in our homes.
    Posted by Ignition at 12:10 0 comments

    All I can say, is that I wish I could get ComCast here With that kind of connection I could send so much stuff from and TO my friends and family and co workers, I would probably never need to use portable hard disks or USB pens again.
    Last edited by acrobat; 11-09-2008 at 05:36 PM.

  2. #2
    Jay is offline
    Gentlemen.. we're history Jay's Avatar
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    Re: One Way Internet - Virgin Media

    I think people forget that its basically two networks one for upload one for download. Telewest:NTL never invested in their upload section of the network.

    The top and bottom is this, download speeds sell upload speeds don't

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