Tom (speedy gonzoles) Scales wrote:
> This statement makes me curious. I regularly download large
> files from the
> Net at 200+Kb (bytes) per second. Internet Explorer upgrades,
> for example,
> just zoom down. That's 1.6mbps. When the whole family is
> using the
> Internet, I can download and still not affect anyone's
> performance.
> I think I'd scream at 'standard' DSL's 384kbps.
>
> Tom
> who lives in a city with enormous capacity and no slowdowns.
Tom, first of all, I believe that MS has a pop of some form in
your city--so that helps explain the fast upgrade downloads.
Secondly, it is not uncommon for you to be speed limited on a
per-download basis from most sites. I've hit sites that will
only give me a 256kbps (bits, not bytes) download speed. But, I
can download three files simultaneously at that limit plus do
video streaming and FTP file tranferring at 700-800kbps up.
Kinda chokes your computer.
Another item worth noting. ATM based DSL systems have QOS
controls that will usually only kick in when the system is under
load. It is not uncommon for our 256kbps customers to get
2-3mbps service during non-peak hours. ATM based systems also
do a lot of buffering which could actually result in higher
speeds than purchased. Unfortunately, anybody who is on
cable-modems most likely is on an IP based DSLAM technology so
most real QOS capabilities are not available and it becomes a
bandwidth sharing situation with all the ills of ethernet coming
to haunt you when you least expect it.
A handy comparison: An ATM based backbone can be oversubscribed
up to 400x wheras IP based backbones start choking at 20x. At
15x oversubscription, our ATM switch is losing about .0080f
the cells. This 15x oversubscription figure is based on QOS
being enforced, but with the exception of a couple times per
day, it is free-running our subscribers so in reality we running
somewhere in the 60x oversubscription, but still taking less
than 180f the bandwidth. Do you suppose we can stick a few
hundred more subscribers on?
Oh, and a nifty little hint for anybody wanting intra-community
WAN on the cheap: Get yourself two Elastic DSL modems and buy a
LADS circuit from the phone company for your two locations.
You'll get up to 10mbps throughput with a cheap monthly bill.
Compare this to a couple point-to-point T1s. This is a great
way to link two buildings together or create a telecommuter
access to your company's LAN. Distance is limited (total length
of three or four cable miles) and LADS service isn't available
everywhere. (LADS is a conditioned dry cable pair)
AG-Schnozz
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