Re: [Hampshire] High bandwidth using DSL lines.

Hi,

Simon Huggins wrote:
> On Mon, Jun 11, 2007 at 12:31:38PM +0100, Simon Capstick wrote:
>> James Courtier-Dutton wrote:
>>> I have a friend who can only get 512Kbps over their DSL line. I was
>>> thinking that they could maybe get 4 DSL lines, and then load balance
>>> over them to make 2Mbits.
>>>
>>> Does anyone know any ISPs that support this sort of service?
>> I'm assuming you're referring to download speeds.
>
> It's possible (nay probable) that his friend just lives far enough away
> from the exchange that 1Mb or 2Mb aren't viable as stable alternatives.
>
> I can't get more than 512kb where I am (in South Reading) due to the
> distance from the exchange (well I might be able to on Max or an ADSL2+
> service from Bethere but I don't really want to risk that just now).
>
>> A 50:1 line running at a maximum of 512Kbps will only give you 10Kbps at
>> peak times, many times slower than an early 1990s modem!
>
> It's rare though that you actually see this and certainly to this extent
> due to the bursty nature of most net traffic.
>
>> A 20:1 ADSL Max line running at 6Mbps will still only give you around
>> 512Kbps of usable (download) bandwidth at peak times.
>
> I'd like to hear if you have actually experienced this first hand. I
> think there would be an open revolt of small businesses if this were
> actually true most of the time.

We do get this. It seems around lunch time we sometimes get a little
packet loss and more often than not heavy contention. I've pretty much
ruled out the problem at our end. The exchange is STSOTON which serves
quite a few businesses in Southampton along with residential areas.
Southampton has a high student population hence my comment on downloads :-)

More annoyingly this is with the more expensive SDSL not ADSL. We have
the same problem with two different reputable ISPs both using BT
wholesale. The lines are showing no errors or abnormal noise. It would
need more careful analysis to be sure exactly what's going on, but the
ISPs won't be interested since they are not dropping below official
contention ratios, and hence are providing the advertised service.

A bigger problem for us is that we are frequently experiencing outages
on our SDSL lines. We've had about 5 or 6 outages over two SDSL lines
in the last 12 months (I'm starting to lose count which is really bad).
There's moderate amounts of building development in the area and I'm
regularly seeing BT vans about fixing things! At one point there were
six BT vans next to our street cabinet.

>
> In reality most people aren't solidly downloading all day (and this is
> being restricted by the caps ISPs are having to bring in) so contention
> isn't brought into play in this extreme way.
>

See my comment on students. I wonder how many of the 40,000+ students
in the area are using P2P apps etc? I reckon a fair proportion of those
students are on our exchange.

My instinct tells me that it is actually people in local offices
watching the BBC news online (or other streaming media) during their
lunch break. The BBC used to start broadcasting at 1pm from their
website (although now it's 24 hours a day) which was around the same
time as our problem (and yes I ruled out that it was us:-). I haven't
tried correlating the particularly bad days with sporting events yet but
I wouldn't be surprised if they matched!

Simon