Re: Re: ISDN vs ADSL

["Paul Gordon" <paul_gordon@xxxxxxx>]

Hi Patrick,

A couple of VERY good points actually! which I should have thought of as
well!

Even more to add to that though, is that obviously ADSL is a single fixed
point to point connection to a single ISP. so you cannot connect to any
other ISP over it, so what happens if your ADSL ISP suffers an outtage?

Likewise with the work access: I regularly work from home and RAS into the
office LAN with my ISDN line. - not possible with ADSL.

In all of these situations, your only choice (unless you're rich enough to
have both ISDN and ADSL) is to fall back on the trusty old analogue
dial-up,
and here, there's a very important point to consider: There is a
"problem"
using an analogue modem over the analogue portion of an ADSL line. This is
mentioned in BT's own FAQ's. It will work, but it is made clear that it is
very likely indeed that you will get lower connection speeds when doing
this. Can't remember the technicalities well enough to repeat them here,
but
something to do with the frequencies used by analogue modems at higher
connection speeds impinging on the ADSL frequencies? (or something like
that) - check out www.btopenworld.com and read the FAQ for the proper
details. Basically, you've probably got little or no chance of 56K
protocols
working (V.90), and whatever connection speeds you can currently achieve
over your analogue BT line, its very likely to be lower after conversion to
ADSL. Also, BT make it plain that they guarantee absolutely nothing at all
over the analogue portion other than plain-old voice calls, so if you get
ADSL and then find that you can't get analogue dial-up connections to work
at all, - you're stuffed! - BT wont help you.

As for the ADSL contention points, well, sort of... True, all internet
traffic is contended at some point, but not usually at the browser to ISP
point! This adds an extra level of bandwidth contention to the equation,
and
if it hits its theoretical "worst case" scenario, could go as low
as 10.2K
(512 / 50, - OK,  unlikely granted, but theoretically possible...) in which
case THIS contention will then become the limiting bottleneck in the
connection. - End result? - slower web access speeds! At least if you have
guaranteed bandwidth to the ISP, you only start contending once you hit the
ISP's backbone, and thereafter the internet backbone itself, right through
to the server your accessing. So I maintain that this is still an important
consideration, that has the potential to materially affect the actual
browsing/downloading speeds you will experience.

I'm also not convinced about the NAT argument and webserver hosting. BT
Openworld's FAQ states that they do not use NAT. I entered into a dialogue
with Openworld's Technical support when I was considering the upgrade (I
think most of that dialogue was posted here) the upshot of this is that
this
is a little bit of a red herring (Only talking about Openworld here, can't
say what the situation with other providers might be), because they just
dont call it NAT, they call it "IP Masquerading", the end result
being the
same: you have 1 dynamic IP address assigned to your ADSL interface at
home,
and another one at the Exchange. Your interface's IP address is not
accessable from the internet, - only the Exchange's address is (to HTTP
traffic anyway). Some experiments performed by list members with ADSL bear
this out, we WERE able to access a listmembers home server by PING and FTP,
but NOT via HTTP. BT's technical support people also told me that it just
plain isn't possible to host a webserver on it. I'd be unbelievably happy
for you (or anyone else for that matter) to prove me (and BT's techies)
wrong on this one! as that would remove the biggest single barrier to me
adopting ADSL. I think more work is required here to establish what the
truth really is?, I think it's yet another case of BT spreading FUD.

Any listmembers able to absolutely, definitively state that they are hosing
a webserver at home on an ADSL line, please step forward!! (and post the
URL
please!)

Paul G.



>Couple of extra points to consider:
>
>If you want to regularly connect to more than 1 ISP (e.g. if your
>work place provides ISDN dial up access and you also want to connect
>to your personal ISP), then using a router will be painful to
>configure.
>
>A serial ISDN TA will work with Linux "out of the box" - it
doesn't
>need any special reconfiguration or kernel recompiles - since it
>looks just like a conventional modem. A 486 will work just fine in
>this configuration as a router/firewall, and provide NAT so that you
>can connect multiple PCs to the net at the same time. You can choose
>whether you manually initiate connection to your ISP or whether it
>dials-on-demand.
>
>And finally... ADSL:
>
>The contention argument is a bit spurious as far as ADSL goes IMHO.
>All internet connections are contended at some point -- its just a
>case of where. Even if you can connect to your ISP at 128k over ISDN,
>inevitably you will be sharing the upstream fixed network bandwidth
>with all those other users dialled in at the same time. For me, the
>value of ADSL comes from the "always on" nature (e.g. no cost
>associated with how often you connect, no significant latency in
>incoming mail delivery).
>
>And Mark, it *is* possible to run webservers over ADSL - so long as
>the ISP providing the service doesn't use NAT. Non-NAT connections
>are available from a number of providers, including EasyNet (which my
>mate has been very satisfied with). I don't know whether any
>providers are offering non-NAT over USB yet, though.
>
>Patrick
>

_________________________________________________________________________
Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com.

Share information about yourself, create your own public profile at
http://profiles.msn.com.


-------------------------- eGroups Sponsor -------------------------~-~>
eGroups eLerts
It's Easy. It's Fun. Best of All, it's Free!
http://click.egroups.com/1/9698/3/_/2065/_/974462703/
---------------------------------------------------------------------_->