[BC] Digital STL

[Tom Hartnett]

Arguments like this give me a real headache. Kind of like "My Toyota
doesn't accelerate on it's own, so they must all be safe".

DSL is a consumer-grade offering. There are rarely any Service Level
Agreements available. It has a medium reliability factor, and repair
is done at the Telco's convenience, not yours. Despite claims like "my
DSL never goes down" there's little value in recommending it for
mission critical 24/7 apps without qualification.

I have 3 DSLs and a T1 installed here at Comrex. One of the DSLs has
been running 3 years without issue. One requires a modem reboot every
two weeks. The third about once every couple of months. When a DSL
line goes down in a way a reboot doesn't fix, it takes about 48 hrs to
get someone on the case. The T1 has failed once in 3 years, and was
fixed within hours under the terms of the SLA.

Folks on this list have a wide range of apps that have different
cost/reliability ratios, and there are certainly apps that fit well
with DSL--remote broadcasting comes to mind. But 24/7 operation over a
DSL should be limited to apps that can tolerate significant downtime,
like feeding translators in sparsely populated areas. Luckily I think
most pros on this list understand that and design mission critical
systems appropriately.

Best

Tom Hartnett
Comrex

---------
>
> Message: 18
> From: "Dana  Puopolo" <dpuopolo at usa.net>
> Content-Type: text/plain; charset=iso-8859-1
>
> Chip,
>
> You are correct about modems-they do fail once in a while. I have mine on a
> gas discharge surge suppressor and also back to back zener protected acress
> the line. The modem is also AC coupled (DSL response is roughly from 100 kHz
> through 1.25 mHz) with .22 uf 400 volt Orange Drops. I also have a couple of
> spare used modems-one bought on ebay for 5 bucks and the other at Saver's for
> $2.50. The one I use now is the Savers one. It's a Netopia and it has a built
> in 4 port switch (My ISP gives me five dynamic public IP addresses). This
> means that I have one less box on my desk. My home is about two miles from the
> C.O. and the loss is 42 db on the download side (with an 8 db noise margin) so